init repo

lab4/.gitignore

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+### Project Specific stuff
+test_run_dir/*
+### XilinxISE template
+# intermediate build files
+*.bgn
+*.bit
+*.bld
+*.cmd_log
+*.drc
+*.ll
+*.lso
+*.msd
+*.msk
+*.ncd
+*.ngc
+*.ngd
+*.ngr
+*.pad
+*.par
+*.pcf
+*.prj
+*.ptwx
+*.rbb
+*.rbd
+*.stx
+*.syr
+*.twr
+*.twx
+*.unroutes
+*.ut
+*.xpi
+*.xst
+*_bitgen.xwbt
+*_envsettings.html
+*_map.map
+*_map.mrp
+*_map.ngm
+*_map.xrpt
+*_ngdbuild.xrpt
+*_pad.csv
+*_pad.txt
+*_par.xrpt
+*_summary.html
+*_summary.xml
+*_usage.xml
+*_xst.xrpt
+
+# project-wide generated files
+*.gise
+par_usage_statistics.html
+usage_statistics_webtalk.html
+webtalk.log
+webtalk_pn.xml
+
+# generated folders
+iseconfig/
+xlnx_auto_0_xdb/
+xst/
+_ngo/
+_xmsgs/
+### Eclipse template
+*.pydevproject
+.metadata
+.gradle
+bin/
+tmp/
+*.tmp
+*.bak
+*.swp
+*~.nib
+local.properties
+.settings/
+.loadpath
+
+# Eclipse Core
+.project
+
+# External tool builders
+.externalToolBuilders/
+
+# Locally stored "Eclipse launch configurations"
+*.launch
+
+# CDT-specific
+.cproject
+
+# JDT-specific (Eclipse Java Development Tools)
+.classpath
+
+# Java annotation processor (APT)
+.factorypath
+
+# PDT-specific
+.buildpath
+
+# sbteclipse plugin
+.target
+
+# TeXlipse plugin
+.texlipse
+### C template
+# Object files
+*.o
+*.ko
+*.obj
+*.elf
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Libraries
+*.lib
+*.a
+*.la
+*.lo
+
+# Shared objects (inc. Windows DLLs)
+*.dll
+*.so
+*.so.*
+*.dylib
+
+# Executables
+*.exe
+*.out
+*.app
+*.i*86
+*.x86_64
+*.hex
+
+# Debug files
+*.dSYM/
+### SBT template
+# Simple Build Tool
+# http://www.scala-sbt.org/release/docs/Getting-Started/Directories.html#configuring-version-control
+
+target/
+lib_managed/
+src_managed/
+project/boot/
+.history
+.cache
+### Emacs template
+# -*- mode: gitignore; -*-
+*~
+\#*\#
+/.emacs.desktop
+/.emacs.desktop.lock
+*.elc
+auto-save-list
+tramp
+.\#*
+
+# Org-mode
+.org-id-locations
+*_archive
+
+# flymake-mode
+*_flymake.*
+
+# eshell files
+/eshell/history
+/eshell/lastdir
+
+# elpa packages
+/elpa/
+
+# reftex files
+*.rel
+
+# AUCTeX auto folder
+/auto/
+
+# cask packages
+.cask/
+### Vim template
+[._]*.s[a-w][a-z]
+[._]s[a-w][a-z]
+*.un~
+Session.vim
+.netrwhist
+*~
+### JetBrains template
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio
+
+*.iml
+
+## Directory-based project format:
+.idea/
+# if you remove the above rule, at least ignore the following:
+
+# User-specific stuff:
+# .idea/workspace.xml
+# .idea/tasks.xml
+# .idea/dictionaries
+
+# Sensitive or high-churn files:
+# .idea/dataSources.ids
+# .idea/dataSources.xml
+# .idea/sqlDataSources.xml
+# .idea/dynamic.xml
+# .idea/uiDesigner.xml
+
+# Gradle:
+# .idea/gradle.xml
+# .idea/libraries
+
+# Mongo Explorer plugin:
+# .idea/mongoSettings.xml
+
+## File-based project format:
+*.ipr
+*.iws
+
+## Plugin-specific files:
+
+# IntelliJ
+/out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+### C++ template
+# Compiled Object files
+*.slo
+*.lo
+*.o
+*.obj
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Compiled Dynamic libraries
+*.so
+*.dylib
+*.dll
+
+# Fortran module files
+*.mod
+
+# Compiled Static libraries
+*.lai
+*.la
+*.a
+*.lib
+
+# Executables
+*.exe
+*.out
+*.app
+### OSX template
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Icon must end with two \r
+Icon
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+### Xcode template
+# Xcode
+#
+# gitignore contributors: remember to update Global/Xcode.gitignore, Objective-C.gitignore & Swift.gitignore
+
+## Build generated
+build/
+DerivedData
+
+## Various settings
+*.pbxuser
+!default.pbxuser
+*.mode1v3
+!default.mode1v3
+*.mode2v3
+!default.mode2v3
+*.perspectivev3
+!default.perspectivev3
+xcuserdata
+
+## Other
+*.xccheckout
+*.moved-aside
+*.xcuserstate
+### Scala template
+*.class
+*.log
+/.bsp
+
+# sbt specific
+.cache
+.history
+.lib/
+dist/*
+target/
+lib_managed/
+src_managed/
+project/boot/
+project/plugins/project/
+
+# Scala-IDE specific
+.scala_dependencies
+.worksheet
+### Java template
+*.class
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.ear
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+
+verilog/*.txt
+verilog/basys3/*
+verilog/pynq/*
+verilog/verilator/*
+!verilog/basys3/test.v
+!verilog/pynq/design_1_wrapper.v
+!verilog/pynq/test.v
+!verilog/pynq/TMDS_PLLVR.v
+!verilog/verilator/sim_main.cpp
+*.jou
+*.log
+.Xil
+vivado/basys3/riscv-basys3
+vivado/pynq/riscv-pynq
+vivado/pynq/NA
+.vscode
+.metals

lab4/Makefile

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+# Copyright 2021 Howard Lau
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+test:
+	sbt test
+
+verilator:
+	sbt "runMain board.verilator.VerilogGenerator"
+	cd verilog/verilator && verilator --trace --exe --cc sim_main.cpp Top.v && make -C obj_dir -f VTop.mk
+
+verilator-sim: verilator
+	cd verilog/verilator && obj_dir/VTop $(SIM_TIME)
+
+basys3:
+	sbt "runMain board.basys3.VerilogGenerator"
+pynq:
+	sbt "runMain board.pynq.VerilogGenerator"
+
+bitstream-basys3: basys3
+	cd vivado/basys3 && vivado -mode batch -source generate_bitstream.tcl
+
+program-basys3: bitstream-basys3
+	cd vivado/basys3 && vivado -mode batch -source program_device.tcl
+
+vivado-sim-basys3: basys3
+	cd vivado/basys3 && vivado -mode batch -source run_simulation.tcl
+bitstream-pynq: pynq
+	cd vivado/pynq && vivado -mode batch -source generate_bitstream.tcl
+
+program-pynq: bitstream-pynq
+	cd vivado/pynq && vivado -mode batch -source program_device.tcl
+
+vivado-sim-pynq: pynq
+	cd vivado/pynq && vivado -mode batch -source run_simulation.tcl
+
+.PHONY: basys3 verilator test bitstream program verilator-sim vivado-sim

lab4/build.sbt

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+import sbt.Keys.libraryDependencies
+// See README.md for license details.
+
+ThisBuild / scalaVersion     := "2.13.10"
+ThisBuild / version          := "0.1.0"
+ThisBuild / organization     := "io.github.howardlau1999"
+
+val chiselVersion = "3.6.0"
+
+lazy val root = (project in file("."))
+  .settings(
+    name := "yatcpu",
+    libraryDependencies ++= Seq(
+      "edu.berkeley.cs" %% "chisel3" % chiselVersion,
+      "edu.berkeley.cs" %% "chiseltest" % "0.6.0" % "test",
+    ),
+    scalacOptions ++= Seq(
+      "-language:reflectiveCalls",
+      "-deprecation",
+      "-feature",
+      "-Xcheckinit",
+    ),
+    addCompilerPlugin("edu.berkeley.cs" % "chisel3-plugin" % chiselVersion cross CrossVersion.full),
+  )

lab4/coremark/yatcpu/core_portme.c

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+/*
+Copyright 2018 Embedded Microprocessor Benchmark Consortium (EEMBC)
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+Original Author: Shay Gal-on
+*/
+#include "coremark.h"
+#include "core_portme.h"
+
+#if VALIDATION_RUN
+volatile ee_s32 seed1_volatile = 0x3415;
+volatile ee_s32 seed2_volatile = 0x3415;
+volatile ee_s32 seed3_volatile = 0x66;
+#endif
+#if PERFORMANCE_RUN
+volatile ee_s32 seed1_volatile = 0x0;
+volatile ee_s32 seed2_volatile = 0x0;
+volatile ee_s32 seed3_volatile = 0x66;
+#endif
+#if PROFILE_RUN
+volatile ee_s32 seed1_volatile = 0x8;
+volatile ee_s32 seed2_volatile = 0x8;
+volatile ee_s32 seed3_volatile = 0x8;
+#endif
+volatile ee_s32 seed4_volatile = ITERATIONS;
+volatile ee_s32 seed5_volatile = 0;
+/* Porting : Timing functions
+        How to capture time and convert to seconds must be ported to whatever is
+   supported by the platform. e.g. Read value from on board RTC, read value from
+   cpu clock cycles performance counter etc. Sample implementation for standard
+   time.h and windows.h definitions included.
+*/
+CORETIMETYPE
+barebones_clock()
+{
+    ee_u32 cyclel;
+    __asm__ __volatile__ (
+        "rdcycle %0" : "=r"(cyclel) : : 
+    );
+    return cyclel;
+}
+/* Define : TIMER_RES_DIVIDER
+        Divider to trade off timer resolution and total time that can be
+   measured.
+
+        Use lower values to increase resolution, but make sure that overflow
+   does not occur. If there are issues with the return value overflowing,
+   increase this value.
+        */
+#define GETMYTIME(_t)              (*_t = barebones_clock())
+#define MYTIMEDIFF(fin, ini)       ((fin) - (ini))
+#define TIMER_RES_DIVIDER          1
+#define SAMPLE_TIME_IMPLEMENTATION 1
+#define EE_TICKS_PER_SEC           (CLOCKS_PER_SEC / TIMER_RES_DIVIDER)
+
+/** Define Host specific (POSIX), or target specific global time variables. */
+static CORETIMETYPE start_time_val, stop_time_val;
+
+/* Function : start_time
+        This function will be called right before starting the timed portion of
+   the benchmark.
+
+        Implementation may be capturing a system timer (as implemented in the
+   example code) or zeroing some system parameters - e.g. setting the cpu clocks
+   cycles to 0.
+*/
+void
+start_time(void)
+{
+    GETMYTIME(&start_time_val);
+}
+/* Function : stop_time
+        This function will be called right after ending the timed portion of the
+   benchmark.
+
+        Implementation may be capturing a system timer (as implemented in the
+   example code) or other system parameters - e.g. reading the current value of
+   cpu cycles counter.
+*/
+void
+stop_time(void)
+{
+    GETMYTIME(&stop_time_val);
+}
+/* Function : get_time
+        Return an abstract "ticks" number that signifies time on the system.
+
+        Actual value returned may be cpu cycles, milliseconds or any other
+   value, as long as it can be converted to seconds by <time_in_secs>. This
+   methodology is taken to accommodate any hardware or simulated platform. The
+   sample implementation returns millisecs by default, and the resolution is
+   controlled by <TIMER_RES_DIVIDER>
+*/
+CORE_TICKS
+get_time(void)
+{
+    CORE_TICKS elapsed
+        = (CORE_TICKS)(MYTIMEDIFF(stop_time_val, start_time_val));
+    return elapsed;
+}
+/* Function : time_in_secs
+        Convert the value returned by get_time to seconds.
+
+        The <secs_ret> type is used to accommodate systems with no support for
+   floating point. Default implementation implemented by the EE_TICKS_PER_SEC
+   macro above.
+*/
+secs_ret
+time_in_secs(CORE_TICKS ticks)
+{
+    secs_ret retval = ((secs_ret)ticks) / (secs_ret)EE_TICKS_PER_SEC;
+    return retval;
+}
+
+ee_u32 default_num_contexts = 1;
+
+/* Function : portable_init
+        Target specific initialization code
+        Test for some common mistakes.
+*/
+void
+portable_init(core_portable *p, int *argc, char *argv[])
+{
+    if (sizeof(ee_ptr_int) != sizeof(ee_u8 *))
+    {
+        ee_printf(
+            "ERROR! Please define ee_ptr_int to a type that holds a "
+            "pointer!\n");
+    }
+    if (sizeof(ee_u32) != 4)
+    {
+        ee_printf("ERROR! Please define ee_u32 to a 32b unsigned type!\n");
+    }
+    p->portable_id = 1;
+}
+/* Function : portable_fini
+        Target specific final code
+*/
+void
+portable_fini(core_portable *p)
+{
+    p->portable_id = 0;
+}
+
+unsigned int
+__mulsi3 (unsigned int a, unsigned int b)
+{
+  unsigned int r = 0;
+
+  while (a)
+    {
+      if (a & 1)
+	r += b;
+      a >>= 1;
+      b <<= 1;
+    }
+  return r;
+}

lab4/coremark/yatcpu/core_portme.h

@@ -0,0 +1,211 @@
+/*
+Copyright 2018 Embedded Microprocessor Benchmark Consortium (EEMBC)
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+Original Author: Shay Gal-on
+*/
+/* Topic : Description
+        This file contains configuration constants required to execute on
+   different platforms
+*/
+#ifndef CORE_PORTME_H
+#define CORE_PORTME_H
+/************************/
+/* Data types and settings */
+/************************/
+/* Configuration : HAS_FLOAT
+        Define to 1 if the platform supports floating point.
+*/
+#ifndef HAS_FLOAT
+#define HAS_FLOAT 0
+#endif
+/* Configuration : HAS_TIME_H
+        Define to 1 if platform has the time.h header file,
+        and implementation of functions thereof.
+*/
+#ifndef HAS_TIME_H
+#define HAS_TIME_H 0
+#define CLOCKS_PER_SEC 100000000
+#endif
+/* Configuration : USE_CLOCK
+        Define to 1 if platform has the time.h header file,
+        and implementation of functions thereof.
+*/
+#ifndef USE_CLOCK
+#define USE_CLOCK 0
+#endif
+/* Configuration : HAS_STDIO
+        Define to 1 if the platform has stdio.h.
+*/
+#ifndef HAS_STDIO
+#define HAS_STDIO 0
+#endif
+/* Configuration : HAS_PRINTF
+        Define to 1 if the platform has stdio.h and implements the printf
+   function.
+*/
+#ifndef HAS_PRINTF
+#define HAS_PRINTF 0
+#endif
+
+/* Definitions : COMPILER_VERSION, COMPILER_FLAGS, MEM_LOCATION
+        Initialize these strings per platform
+*/
+#ifndef COMPILER_VERSION
+#ifdef __GNUC__
+#define COMPILER_VERSION "GCC"__VERSION__
+#else
+#define COMPILER_VERSION "Please put compiler version here (e.g. gcc 4.1)"
+#endif
+#endif
+#ifndef COMPILER_FLAGS
+#define COMPILER_FLAGS \
+    FLAGS_STR /* "Please put compiler flags here (e.g. -o3)" */
+#endif
+#ifndef MEM_LOCATION
+#define MEM_LOCATION "STACK"
+#endif
+
+/* Data Types :
+        To avoid compiler issues, define the data types that need ot be used for
+   8b, 16b and 32b in <core_portme.h>.
+
+        *Imprtant* :
+        ee_ptr_int needs to be the data type used to hold pointers, otherwise
+   coremark may fail!!!
+*/
+typedef signed short   ee_s16;
+typedef unsigned short ee_u16;
+typedef signed int     ee_s32;
+typedef double         ee_f32;
+typedef unsigned char  ee_u8;
+typedef unsigned int   ee_u32;
+typedef ee_u32         ee_ptr_int;
+typedef ee_u32         ee_size_t;
+#define NULL ((void *)0)
+/* align_mem :
+        This macro is used to align an offset to point to a 32b value. It is
+   used in the Matrix algorithm to initialize the input memory blocks.
+*/
+#define align_mem(x) (void *)(4 + (((ee_ptr_int)(x)-1) & ~3))
+
+/* Configuration : CORE_TICKS
+        Define type of return from the timing functions.
+ */
+#define CORETIMETYPE ee_u32
+typedef ee_u32 CORE_TICKS;
+
+/* Configuration : SEED_METHOD
+        Defines method to get seed values that cannot be computed at compile
+   time.
+
+        Valid values :
+        SEED_ARG - from command line.
+        SEED_FUNC - from a system function.
+        SEED_VOLATILE - from volatile variables.
+*/
+#ifndef SEED_METHOD
+#define SEED_METHOD SEED_VOLATILE
+#endif
+
+/* Configuration : MEM_METHOD
+        Defines method to get a block of memry.
+
+        Valid values :
+        MEM_MALLOC - for platforms that implement malloc and have malloc.h.
+        MEM_STATIC - to use a static memory array.
+        MEM_STACK - to allocate the data block on the stack (NYI).
+*/
+#ifndef MEM_METHOD
+#define MEM_METHOD MEM_STATIC
+#endif
+
+/* Configuration : MULTITHREAD
+        Define for parallel execution
+
+        Valid values :
+        1 - only one context (default).
+        N>1 - will execute N copies in parallel.
+
+        Note :
+        If this flag is defined to more then 1, an implementation for launching
+   parallel contexts must be defined.
+
+        Two sample implementations are provided. Use <USE_PTHREAD> or <USE_FORK>
+   to enable them.
+
+        It is valid to have a different implementation of <core_start_parallel>
+   and <core_end_parallel> in <core_portme.c>, to fit a particular architecture.
+*/
+#ifndef MULTITHREAD
+#define MULTITHREAD 1
+#define USE_PTHREAD 0
+#define USE_FORK    0
+#define USE_SOCKET  0
+#endif
+
+/* Configuration : MAIN_HAS_NOARGC
+        Needed if platform does not support getting arguments to main.
+
+        Valid values :
+        0 - argc/argv to main is supported
+        1 - argc/argv to main is not supported
+
+        Note :
+        This flag only matters if MULTITHREAD has been defined to a value
+   greater then 1.
+*/
+#ifndef MAIN_HAS_NOARGC
+#define MAIN_HAS_NOARGC 1
+#endif
+
+/* Configuration : MAIN_HAS_NORETURN
+        Needed if platform does not support returning a value from main.
+
+        Valid values :
+        0 - main returns an int, and return value will be 0.
+        1 - platform does not support returning a value from main
+*/
+#ifndef MAIN_HAS_NORETURN
+#define MAIN_HAS_NORETURN 0
+#endif
+
+/* Variable : default_num_contexts
+        Not used for this simple port, must contain the value 1.
+*/
+extern ee_u32 default_num_contexts;
+
+typedef struct CORE_PORTABLE_S
+{
+    ee_u8 portable_id;
+} core_portable;
+
+/* target specific init/fini */
+void portable_init(core_portable *p, int *argc, char *argv[]);
+void portable_fini(core_portable *p);
+
+#if !defined(PROFILE_RUN) && !defined(PERFORMANCE_RUN) \
+    && !defined(VALIDATION_RUN)
+#if (TOTAL_DATA_SIZE == 1200)
+#define PROFILE_RUN 1
+#elif (TOTAL_DATA_SIZE == 2000)
+#define PERFORMANCE_RUN 1
+#else
+#define VALIDATION_RUN 1
+#endif
+#endif
+
+int ee_printf(const char *fmt, ...);
+
+#endif /* CORE_PORTME_H */

lab4/coremark/yatcpu/core_portme.mak

@@ -0,0 +1,92 @@
+# Copyright 2018 Embedded Microprocessor Benchmark Consortium (EEMBC)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# 
+# Original Author: Shay Gal-on
+
+#File : core_portme.mak
+
+# Flag : OUTFLAG
+#	Use this flag to define how to to get an executable (e.g -o)
+OUTFLAG= -o
+# Flag : CC
+#	Use this flag to define compiler to use
+CC 		= clang
+# Flag : LD
+#	Use this flag to define compiler to use
+LD		= ld.lld
+# Flag : AS
+#	Use this flag to define compiler to use
+AS		= clang
+# Flag : CFLAGS
+#	Use this flag to define compiler options. Note, you can add compiler options from the command line using XCFLAGS="other flags"
+PORT_CFLAGS = -O0 -g --target=riscv32-unknown-elf -march=rv32i -mabi=ilp32
+FLAGS_STR = "$(PORT_CFLAGS) $(XCFLAGS) $(XLFLAGS) $(LFLAGS_END)"
+CFLAGS = $(PORT_CFLAGS) -I$(PORT_DIR) -I. -DFLAGS_STR=\"$(FLAGS_STR)\" 
+#Flag : LFLAGS_END
+#	Define any libraries needed for linking or other flags that should come at the end of the link line (e.g. linker scripts). 
+#	Note : On certain platforms, the default clock_gettime implementation is supported but requires linking of librt.
+SEPARATE_COMPILE=1
+# Flag : SEPARATE_COMPILE
+# You must also define below how to create an object file, and how to link.
+OBJOUT 	= -o
+LFLAGS 	= -T $(PORT_DIR)/link.ld
+ASFLAGS = -c --target=riscv32-unknown-elf -march=rv32i -mabi=ilp32
+OFLAG 	= -o
+COUT 	= -c
+
+LFLAGS_END = 
+# Flag : PORT_SRCS
+# 	Port specific source files can be added here
+#	You may also need cvt.c if the fcvt functions are not provided as intrinsics by your compiler!
+PORT_SRCS = $(PORT_DIR)/core_portme.c $(PORT_DIR)/ee_printf.c $(PORT_DIR)/div.s $(PORT_DIR)/init.s
+vpath %.c $(PORT_DIR)
+vpath %.s $(PORT_DIR)
+
+PORT_OBJS = $(PORT_DIR)/init$(OEXT) $(PORT_DIR)/core_portme$(OEXT) $(PORT_DIR)/ee_printf$(OEXT) $(PORT_DIR)/div$(OEXT)
+PORT_CLEAN = *$(OEXT) $(OUTFILE).asmbin
+
+# Flag : LOAD
+#	For a simple port, we assume self hosted compile and run, no load needed.
+
+# Flag : RUN
+#	For a simple port, we assume self hosted compile and run, simple invocation of the executable
+
+LOAD = echo "Please set LOAD to the process of loading the executable to the flash"
+RUN = echo "Please set LOAD to the process of running the executable (e.g. via jtag, or board reset)"
+
+OEXT = .o
+EXE = .bin
+
+$(OPATH)$(PORT_DIR)/%$(OEXT) : %.c
+	$(CC) $(CFLAGS) $(XCFLAGS) $(COUT) $< $(OBJOUT) $@
+
+$(OPATH)%$(OEXT) : %.c
+	$(CC) $(CFLAGS) $(XCFLAGS) $(COUT) $< $(OBJOUT) $@
+
+$(OPATH)$(PORT_DIR)/%$(OEXT) : %.s
+	$(AS) $(ASFLAGS) $< $(OBJOUT) $@
+
+# Target : port_pre% and port_post%
+# For the purpose of this simple port, no pre or post steps needed.
+
+.PHONY : port_prebuild port_postbuild port_prerun port_postrun port_preload port_postload
+port_postbuild: $(OUTFILE)
+	llvm-objcopy -O binary -j .text -j .data $(OUTFILE) $(OUTFILE).asmbin
+port_pre% port_post% : 
+
+# FLAG : OPATH
+# Path to the output folder. Default - current folder.
+OPATH = ./
+MKDIR = mkdir -p
+

lab4/coremark/yatcpu/cvt.c

@@ -0,0 +1,127 @@
+/*
+Copyright 2018 Embedded Microprocessor Benchmark Consortium (EEMBC)
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+#include <math.h>
+#define CVTBUFSIZE 80
+static char CVTBUF[CVTBUFSIZE];
+
+static char *
+cvt(double arg, int ndigits, int *decpt, int *sign, char *buf, int eflag)
+{
+    int    r2;
+    double fi, fj;
+    char * p, *p1;
+
+    if (ndigits < 0)
+        ndigits = 0;
+    if (ndigits >= CVTBUFSIZE - 1)
+        ndigits = CVTBUFSIZE - 2;
+    r2    = 0;
+    *sign = 0;
+    p     = &buf[0];
+    if (arg < 0)
+    {
+        *sign = 1;
+        arg   = -arg;
+    }
+    arg = modf(arg, &fi);
+    p1  = &buf[CVTBUFSIZE];
+
+    if (fi != 0)
+    {
+        p1 = &buf[CVTBUFSIZE];
+        while (fi != 0)
+        {
+            fj    = modf(fi / 10, &fi);
+            *--p1 = (int)((fj + .03) * 10) + '0';
+            r2++;
+        }
+        while (p1 < &buf[CVTBUFSIZE])
+            *p++ = *p1++;
+    }
+    else if (arg > 0)
+    {
+        while ((fj = arg * 10) < 1)
+        {
+            arg = fj;
+            r2--;
+        }
+    }
+    p1 = &buf[ndigits];
+    if (eflag == 0)
+        p1 += r2;
+    *decpt = r2;
+    if (p1 < &buf[0])
+    {
+        buf[0] = '\0';
+        return buf;
+    }
+    while (p <= p1 && p < &buf[CVTBUFSIZE])
+    {
+        arg *= 10;
+        arg  = modf(arg, &fj);
+        *p++ = (int)fj + '0';
+    }
+    if (p1 >= &buf[CVTBUFSIZE])
+    {
+        buf[CVTBUFSIZE - 1] = '\0';
+        return buf;
+    }
+    p = p1;
+    *p1 += 5;
+    while (*p1 > '9')
+    {
+        *p1 = '0';
+        if (p1 > buf)
+            ++*--p1;
+        else
+        {
+            *p1 = '1';
+            (*decpt)++;
+            if (eflag == 0)
+            {
+                if (p > buf)
+                    *p = '0';
+                p++;
+            }
+        }
+    }
+    *p = '\0';
+    return buf;
+}
+
+char *
+ecvt(double arg, int ndigits, int *decpt, int *sign)
+{
+    return cvt(arg, ndigits, decpt, sign, CVTBUF, 1);
+}
+
+char *
+ecvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf)
+{
+    return cvt(arg, ndigits, decpt, sign, buf, 1);
+}
+
+char *
+fcvt(double arg, int ndigits, int *decpt, int *sign)
+{
+    return cvt(arg, ndigits, decpt, sign, CVTBUF, 0);
+}
+
+char *
+fcvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf)
+{
+    return cvt(arg, ndigits, decpt, sign, buf, 0);
+}

lab4/coremark/yatcpu/div.s

@@ -0,0 +1,71 @@
+.text
+.globl __divsi3
+__divsi3:
+  bltz  a0, .L10
+  bltz  a1, .L11
+
+.globl __udivsi3
+__udivsi3:
+  mv    a2, a1
+  mv    a1, a0
+  li    a0, -1
+  beqz  a2, .L5
+  li    a3, 1
+  bgeu  a2, a1, .L2
+.L1:
+  blez  a2, .L2
+  slli  a2, a2, 1
+  slli  a3, a3, 1
+  bgtu  a1, a2, .L1
+.L2:
+  li    a0, 0
+.L3:
+  bltu  a1, a2, .L4
+  sub   a1, a1, a2
+  or    a0, a0, a3
+.L4:
+  srli  a3, a3, 1
+  srli  a2, a2, 1
+  bnez  a3, .L3
+.L5:
+  ret
+
+.globl __umodsi3
+__umodsi3:
+  move  t0, ra
+  jal   __udivsi3
+  move  a0, a1
+  jr    t0
+
+.L10:
+  neg   a0, a0
+  bgtz  a1, .L12
+
+  neg   a1, a1
+  j     __udivsi3
+.L11:
+  neg   a1, a1
+.L12:
+  move  t0, ra
+  jal   __udivsi3
+  neg   a0, a0
+  jr    t0
+
+.globl __modsi3
+__modsi3:
+  move   t0, ra
+  bltz   a1, .L31
+  bltz   a0, .L32
+.L30:
+  jal    __udivsi3
+  move   a0, a1
+  jr     t0
+.L31:
+  neg    a1, a1
+  bgez   a0, .L30
+.L32:
+  neg    a0, a0
+  jal    __udivsi3
+  neg    a0, a1
+  jr     t0
+

lab4/coremark/yatcpu/ee_printf.c

@@ -0,0 +1,687 @@
+/*
+Copyright 2018 Embedded Microprocessor Benchmark Consortium (EEMBC)
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+#include <coremark.h>
+#include <stdarg.h>
+
+#define ZEROPAD   (1 << 0) /* Pad with zero */
+#define SIGN      (1 << 1) /* Unsigned/signed long */
+#define PLUS      (1 << 2) /* Show plus */
+#define SPACE     (1 << 3) /* Spacer */
+#define LEFT      (1 << 4) /* Left justified */
+#define HEX_PREP  (1 << 5) /* 0x */
+#define UPPERCASE (1 << 6) /* 'ABCDEF' */
+
+#define is_digit(c) ((c) >= '0' && (c) <= '9')
+
+static char *    digits       = "0123456789abcdefghijklmnopqrstuvwxyz";
+static char *    upper_digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+static ee_size_t strnlen(const char *s, ee_size_t count);
+
+static ee_size_t
+strnlen(const char *s, ee_size_t count)
+{
+    const char *sc;
+    for (sc = s; *sc != '\0' && count--; ++sc)
+        ;
+    return sc - s;
+}
+
+static int
+skip_atoi(const char **s)
+{
+    int i = 0;
+    while (is_digit(**s))
+        i = i * 10 + *((*s)++) - '0';
+    return i;
+}
+
+static char *
+number(char *str, long num, int base, int size, int precision, int type)
+{
+    char  c, sign, tmp[66];
+    char *dig = digits;
+    int   i;
+
+    if (type & UPPERCASE)
+        dig = upper_digits;
+    if (type & LEFT)
+        type &= ~ZEROPAD;
+    if (base < 2 || base > 36)
+        return 0;
+
+    c    = (type & ZEROPAD) ? '0' : ' ';
+    sign = 0;
+    if (type & SIGN)
+    {
+        if (num < 0)
+        {
+            sign = '-';
+            num  = -num;
+            size--;
+        }
+        else if (type & PLUS)
+        {
+            sign = '+';
+            size--;
+        }
+        else if (type & SPACE)
+        {
+            sign = ' ';
+            size--;
+        }
+    }
+
+    if (type & HEX_PREP)
+    {
+        if (base == 16)
+            size -= 2;
+        else if (base == 8)
+            size--;
+    }
+
+    i = 0;
+
+    if (num == 0)
+        tmp[i++] = '0';
+    else
+    {
+        while (num != 0)
+        {
+            tmp[i++] = dig[((unsigned long)num) % (unsigned)base];
+            num      = ((unsigned long)num) / (unsigned)base;
+        }
+    }
+
+    if (i > precision)
+        precision = i;
+    size -= precision;
+    if (!(type & (ZEROPAD | LEFT)))
+        while (size-- > 0)
+            *str++ = ' ';
+    if (sign)
+        *str++ = sign;
+
+    if (type & HEX_PREP)
+    {
+        if (base == 8)
+            *str++ = '0';
+        else if (base == 16)
+        {
+            *str++ = '0';
+            *str++ = digits[33];
+        }
+    }
+
+    if (!(type & LEFT))
+        while (size-- > 0)
+            *str++ = c;
+    while (i < precision--)
+        *str++ = '0';
+    while (i-- > 0)
+        *str++ = tmp[i];
+    while (size-- > 0)
+        *str++ = ' ';
+
+    return str;
+}
+
+static char *
+eaddr(char *str, unsigned char *addr, int size, int precision, int type)
+{
+    char  tmp[24];
+    char *dig = digits;
+    int   i, len;
+
+    if (type & UPPERCASE)
+        dig = upper_digits;
+    len = 0;
+    for (i = 0; i < 6; i++)
+    {
+        if (i != 0)
+            tmp[len++] = ':';
+        tmp[len++] = dig[addr[i] >> 4];
+        tmp[len++] = dig[addr[i] & 0x0F];
+    }
+
+    if (!(type & LEFT))
+        while (len < size--)
+            *str++ = ' ';
+    for (i = 0; i < len; ++i)
+        *str++ = tmp[i];
+    while (len < size--)
+        *str++ = ' ';
+
+    return str;
+}
+
+static char *
+iaddr(char *str, unsigned char *addr, int size, int precision, int type)
+{
+    char tmp[24];
+    int  i, n, len;
+
+    len = 0;
+    for (i = 0; i < 4; i++)
+    {
+        if (i != 0)
+            tmp[len++] = '.';
+        n = addr[i];
+
+        if (n == 0)
+            tmp[len++] = digits[0];
+        else
+        {
+            if (n >= 100)
+            {
+                tmp[len++] = digits[n / 100];
+                n          = n % 100;
+                tmp[len++] = digits[n / 10];
+                n          = n % 10;
+            }
+            else if (n >= 10)
+            {
+                tmp[len++] = digits[n / 10];
+                n          = n % 10;
+            }
+
+            tmp[len++] = digits[n];
+        }
+    }
+
+    if (!(type & LEFT))
+        while (len < size--)
+            *str++ = ' ';
+    for (i = 0; i < len; ++i)
+        *str++ = tmp[i];
+    while (len < size--)
+        *str++ = ' ';
+
+    return str;
+}
+
+#if HAS_FLOAT
+
+char *      ecvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf);
+char *      fcvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf);
+static void ee_bufcpy(char *d, char *s, int count);
+
+void
+ee_bufcpy(char *pd, char *ps, int count)
+{
+    char *pe = ps + count;
+    while (ps != pe)
+        *pd++ = *ps++;
+}
+
+static void
+parse_float(double value, char *buffer, char fmt, int precision)
+{
+    int   decpt, sign, exp, pos;
+    char *digits = NULL;
+    char  cvtbuf[80];
+    int   capexp = 0;
+    int   magnitude;
+
+    if (fmt == 'G' || fmt == 'E')
+    {
+        capexp = 1;
+        fmt += 'a' - 'A';
+    }
+
+    if (fmt == 'g')
+    {
+        digits    = ecvtbuf(value, precision, &decpt, &sign, cvtbuf);
+        magnitude = decpt - 1;
+        if (magnitude < -4 || magnitude > precision - 1)
+        {
+            fmt = 'e';
+            precision -= 1;
+        }
+        else
+        {
+            fmt = 'f';
+            precision -= decpt;
+        }
+    }
+
+    if (fmt == 'e')
+    {
+        digits = ecvtbuf(value, precision + 1, &decpt, &sign, cvtbuf);
+
+        if (sign)
+            *buffer++ = '-';
+        *buffer++ = *digits;
+        if (precision > 0)
+            *buffer++ = '.';
+        ee_bufcpy(buffer, digits + 1, precision);
+        buffer += precision;
+        *buffer++ = capexp ? 'E' : 'e';
+
+        if (decpt == 0)
+        {
+            if (value == 0.0)
+                exp = 0;
+            else
+                exp = -1;
+        }
+        else
+            exp = decpt - 1;
+
+        if (exp < 0)
+        {
+            *buffer++ = '-';
+            exp       = -exp;
+        }
+        else
+            *buffer++ = '+';
+
+        buffer[2] = (exp % 10) + '0';
+        exp       = exp / 10;
+        buffer[1] = (exp % 10) + '0';
+        exp       = exp / 10;
+        buffer[0] = (exp % 10) + '0';
+        buffer += 3;
+    }
+    else if (fmt == 'f')
+    {
+        digits = fcvtbuf(value, precision, &decpt, &sign, cvtbuf);
+        if (sign)
+            *buffer++ = '-';
+        if (*digits)
+        {
+            if (decpt <= 0)
+            {
+                *buffer++ = '0';
+                *buffer++ = '.';
+                for (pos = 0; pos < -decpt; pos++)
+                    *buffer++ = '0';
+                while (*digits)
+                    *buffer++ = *digits++;
+            }
+            else
+            {
+                pos = 0;
+                while (*digits)
+                {
+                    if (pos++ == decpt)
+                        *buffer++ = '.';
+                    *buffer++ = *digits++;
+                }
+            }
+        }
+        else
+        {
+            *buffer++ = '0';
+            if (precision > 0)
+            {
+                *buffer++ = '.';
+                for (pos = 0; pos < precision; pos++)
+                    *buffer++ = '0';
+            }
+        }
+    }
+
+    *buffer = '\0';
+}
+
+static void
+decimal_point(char *buffer)
+{
+    while (*buffer)
+    {
+        if (*buffer == '.')
+            return;
+        if (*buffer == 'e' || *buffer == 'E')
+            break;
+        buffer++;
+    }
+
+    if (*buffer)
+    {
+        int n = strnlen(buffer, 256);
+        while (n > 0)
+        {
+            buffer[n + 1] = buffer[n];
+            n--;
+        }
+
+        *buffer = '.';
+    }
+    else
+    {
+        *buffer++ = '.';
+        *buffer   = '\0';
+    }
+}
+
+static void
+cropzeros(char *buffer)
+{
+    char *stop;
+
+    while (*buffer && *buffer != '.')
+        buffer++;
+    if (*buffer++)
+    {
+        while (*buffer && *buffer != 'e' && *buffer != 'E')
+            buffer++;
+        stop = buffer--;
+        while (*buffer == '0')
+            buffer--;
+        if (*buffer == '.')
+            buffer--;
+        while (buffer != stop)
+            *++buffer = 0;
+    }
+}
+
+static char *
+flt(char *str, double num, int size, int precision, char fmt, int flags)
+{
+    char tmp[80];
+    char c, sign;
+    int  n, i;
+
+    // Left align means no zero padding
+    if (flags & LEFT)
+        flags &= ~ZEROPAD;
+
+    // Determine padding and sign char
+    c    = (flags & ZEROPAD) ? '0' : ' ';
+    sign = 0;
+    if (flags & SIGN)
+    {
+        if (num < 0.0)
+        {
+            sign = '-';
+            num  = -num;
+            size--;
+        }
+        else if (flags & PLUS)
+        {
+            sign = '+';
+            size--;
+        }
+        else if (flags & SPACE)
+        {
+            sign = ' ';
+            size--;
+        }
+    }
+
+    // Compute the precision value
+    if (precision < 0)
+        precision = 6; // Default precision: 6
+
+    // Convert floating point number to text
+    parse_float(num, tmp, fmt, precision);
+
+    if ((flags & HEX_PREP) && precision == 0)
+        decimal_point(tmp);
+    if (fmt == 'g' && !(flags & HEX_PREP))
+        cropzeros(tmp);
+
+    n = strnlen(tmp, 256);
+
+    // Output number with alignment and padding
+    size -= n;
+    if (!(flags & (ZEROPAD | LEFT)))
+        while (size-- > 0)
+            *str++ = ' ';
+    if (sign)
+        *str++ = sign;
+    if (!(flags & LEFT))
+        while (size-- > 0)
+            *str++ = c;
+    for (i = 0; i < n; i++)
+        *str++ = tmp[i];
+    while (size-- > 0)
+        *str++ = ' ';
+
+    return str;
+}
+
+#endif
+
+static int
+ee_vsprintf(char *buf, const char *fmt, va_list args)
+{
+    int           len;
+    unsigned long num;
+    int           i, base;
+    char *        str;
+    char *        s;
+
+    int flags; // Flags to number()
+
+    int field_width; // Width of output field
+    int precision;   // Min. # of digits for integers; max number of chars for
+                     // from string
+    int qualifier;   // 'h', 'l', or 'L' for integer fields
+
+    for (str = buf; *fmt; fmt++)
+    {
+        if (*fmt != '%')
+        {
+            *str++ = *fmt;
+            continue;
+        }
+
+        // Process flags
+        flags = 0;
+    repeat:
+        fmt++; // This also skips first '%'
+        switch (*fmt)
+        {
+            case '-':
+                flags |= LEFT;
+                goto repeat;
+            case '+':
+                flags |= PLUS;
+                goto repeat;
+            case ' ':
+                flags |= SPACE;
+                goto repeat;
+            case '#':
+                flags |= HEX_PREP;
+                goto repeat;
+            case '0':
+                flags |= ZEROPAD;
+                goto repeat;
+        }
+
+        // Get field width
+        field_width = -1;
+        if (is_digit(*fmt))
+            field_width = skip_atoi(&fmt);
+        else if (*fmt == '*')
+        {
+            fmt++;
+            field_width = va_arg(args, int);
+            if (field_width < 0)
+            {
+                field_width = -field_width;
+                flags |= LEFT;
+            }
+        }
+
+        // Get the precision
+        precision = -1;
+        if (*fmt == '.')
+        {
+            ++fmt;
+            if (is_digit(*fmt))
+                precision = skip_atoi(&fmt);
+            else if (*fmt == '*')
+            {
+                ++fmt;
+                precision = va_arg(args, int);
+            }
+            if (precision < 0)
+                precision = 0;
+        }
+
+        // Get the conversion qualifier
+        qualifier = -1;
+        if (*fmt == 'l' || *fmt == 'L')
+        {
+            qualifier = *fmt;
+            fmt++;
+        }
+
+        // Default base
+        base = 10;
+
+        switch (*fmt)
+        {
+            case 'c':
+                if (!(flags & LEFT))
+                    while (--field_width > 0)
+                        *str++ = ' ';
+                *str++ = (unsigned char)va_arg(args, int);
+                while (--field_width > 0)
+                    *str++ = ' ';
+                continue;
+
+            case 's':
+                s = va_arg(args, char *);
+                if (!s)
+                    s = "<NULL>";
+                len = strnlen(s, precision);
+                if (!(flags & LEFT))
+                    while (len < field_width--)
+                        *str++ = ' ';
+                for (i = 0; i < len; ++i)
+                    *str++ = *s++;
+                while (len < field_width--)
+                    *str++ = ' ';
+                continue;
+
+            case 'p':
+                if (field_width == -1)
+                {
+                    field_width = 2 * sizeof(void *);
+                    flags |= ZEROPAD;
+                }
+                str = number(str,
+                             (unsigned long)va_arg(args, void *),
+                             16,
+                             field_width,
+                             precision,
+                             flags);
+                continue;
+
+            case 'A':
+                flags |= UPPERCASE;
+
+            case 'a':
+                if (qualifier == 'l')
+                    str = eaddr(str,
+                                va_arg(args, unsigned char *),
+                                field_width,
+                                precision,
+                                flags);
+                else
+                    str = iaddr(str,
+                                va_arg(args, unsigned char *),
+                                field_width,
+                                precision,
+                                flags);
+                continue;
+
+            // Integer number formats - set up the flags and "break"
+            case 'o':
+                base = 8;
+                break;
+
+            case 'X':
+                flags |= UPPERCASE;
+
+            case 'x':
+                base = 16;
+                break;
+
+            case 'd':
+            case 'i':
+                flags |= SIGN;
+
+            case 'u':
+                break;
+
+#if HAS_FLOAT
+
+            case 'f':
+                str = flt(str,
+                          va_arg(args, double),
+                          field_width,
+                          precision,
+                          *fmt,
+                          flags | SIGN);
+                continue;
+
+#endif
+
+            default:
+                if (*fmt != '%')
+                    *str++ = '%';
+                if (*fmt)
+                    *str++ = *fmt;
+                else
+                    --fmt;
+                continue;
+        }
+
+        if (qualifier == 'l')
+            num = va_arg(args, unsigned long);
+        else if (flags & SIGN)
+            num = va_arg(args, int);
+        else
+            num = va_arg(args, unsigned int);
+
+        str = number(str, num, base, field_width, precision, flags);
+    }
+
+    *str = '\0';
+    return str - buf;
+}
+
+void
+uart_send_char(char c)
+{
+  *((volatile unsigned int *) (0x40000010)) = c;
+}
+
+int
+ee_printf(const char *fmt, ...)
+{
+    char    buf[1024], *p;
+    va_list args;
+    int     n = 0;
+
+    va_start(args, fmt);
+    ee_vsprintf(buf, fmt, args);
+    va_end(args);
+    p = buf;
+    while (*p)
+    {
+        uart_send_char(*p);
+        n++;
+        p++;
+    }
+
+    return n;
+}

lab4/coremark/yatcpu/init.s

@@ -0,0 +1,16 @@
+.section .text.init
+.globl _start
+_start:
+    li sp, 4092
+    call main
+    li x1, 0xBABECAFE
+write_tohost:
+    sw x1, tohost, x0
+loop:
+    j loop
+
+.pushsection .tohost,"aw",@progbits
+    .align 4
+    .global tohost
+    tohost: .word 0
+.popsection

lab4/coremark/yatcpu/link.ld

@@ -0,0 +1,12 @@
+OUTPUT_ARCH( "riscv" )
+ENTRY(_start)
+
+SECTIONS
+{
+  . = 0x00001000;
+  .text : { *(.text.init) *(.text.startup) *(.text) }
+  .data ALIGN(0x1000) : { *(.data*) *(.rodata*) *(.sdata*) }
+  .tohost ALIGN(0x1000) : { *(.tohost) }
+  .bss : { *(.bss) }
+  _end = .;
+}

lab4/csrc/CMakeLists.txt

@@ -0,0 +1,66 @@
+# Make CMake happy
+cmake_minimum_required(VERSION 3.18)
+project(yatcpu-programs C CXX ASM)
+
+# Setting variables
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0 --target=riscv32-unknown-elf -march=rv32i -mabi=ilp32")
+set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -O0 --target=riscv32-unknown-elf -march=rv32i -mabi=ilp32")
+set(C_PROGRAMS tetris hello fibonacci quicksort paging tetris_mmu)
+set(ASM_PROGRAMS mmio sb)
+set(LINKER_SCRIPT ${CMAKE_SOURCE_DIR}/link.lds)
+set(LINKER_FLAGS -T ${LINKER_SCRIPT}) 
+set(OBJCOPY_ARGS -O binary -j .text -j .data)
+if(NOT DEST_DIR)
+	set(DEST_DIR "../src/main/resources")
+endif()
+
+# Let CMake know that there exists header files
+include_directories("${CMAKE_SOURCE_DIR}")
+
+add_library(prelude init.S)
+set_target_properties(prelude PROPERTIES LINK_DEPENDS ${LINKER_SCRIPT})
+
+# Let's build our executables
+foreach(program IN LISTS C_PROGRAMS)
+	add_executable(${program} ${program}.c)
+	set_target_properties(${program} PROPERTIES LINK_DEPENDS ${LINKER_SCRIPT})
+	target_link_libraries(${program} prelude ${LINKER_FLAGS})
+endforeach()
+
+foreach(program IN LISTS ASM_PROGRAMS)
+	add_executable(${program} ${program}.S)
+	set_target_properties(${program} PROPERTIES LINK_DEPENDS ${LINKER_SCRIPT})
+endforeach()
+
+set(PROGRAMS litenes)
+# NES Emulator
+include_directories(${CMAKE_SOURCE_DIR}/LiteNES/include)
+add_definitions(-DYATCPU)
+add_library(fce
+	${CMAKE_SOURCE_DIR}/LiteNES/src/fce/common.c
+	${CMAKE_SOURCE_DIR}/LiteNES/src/fce/cpu-addressing.c
+	${CMAKE_SOURCE_DIR}/LiteNES/src/fce/cpu.c
+	${CMAKE_SOURCE_DIR}/LiteNES/src/fce/fce.c
+	${CMAKE_SOURCE_DIR}/LiteNES/src/fce/memory.c
+	${CMAKE_SOURCE_DIR}/LiteNES/src/fce/mmc.c
+	${CMAKE_SOURCE_DIR}/LiteNES/src/fce/ppu.c
+	${CMAKE_SOURCE_DIR}/LiteNES/src/fce/psg.c
+)
+target_compile_options(fce PRIVATE "-O3")
+add_executable(litenes
+	${CMAKE_SOURCE_DIR}/LiteNES/src/main.c
+  ${CMAKE_SOURCE_DIR}/LiteNES/src/hal.c
+  ${CMAKE_SOURCE_DIR}/LiteNES/src/rom.c
+)
+set_target_properties(litenes PROPERTIES LINK_DEPENDS ${LINKER_SCRIPT})
+target_link_libraries(litenes prelude fce ${LINKER_FLAGS})
+
+# Copy the .text and .data section to .asmbin files
+foreach(program IN LISTS C_PROGRAMS ASM_PROGRAMS PROGRAMS)
+	add_custom_command(
+		TARGET ${program}
+		POST_BUILD
+		COMMAND ${CMAKE_OBJCOPY} ARGS ${OBJCOPY_ARGS} $<TARGET_FILE:${program}> ${CMAKE_SOURCE_DIR}/${DEST_DIR}/${program}.asmbin
+	)
+endforeach()
+

lab4/csrc/build.bat

@@ -0,0 +1,3 @@
+rmdir /Q /S build
+cmake -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake -G"NMake Makefiles" -B build .
+cmake --build build

lab4/csrc/build.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+rm -rf build
+cmake -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake -B build . && cmake --build build --parallel `nproc`

lab4/csrc/fibonacci.c

@@ -0,0 +1,22 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+int fib(int a) {
+  if (a == 1 || a == 2) return 1;
+  return fib(a - 1) + fib(a - 2);
+}
+
+int main() {
+  *(int *)(4) = fib(10);
+}

lab4/csrc/hello.c

@@ -0,0 +1,175 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "mmio.h"
+
+#define MUL80(x) (((x) << 6) + ((x) << 4))
+
+struct screen {
+	unsigned char row, col;
+} scr;
+
+void copy_line(int prev, int cur) {
+	int *prev_vram_start = ((int *) (MUL80(prev) + VRAM_BASE));
+	int *cur_vram_start = ((int *) (MUL80(cur) + VRAM_BASE));
+	for (int i = 0; i < 20; ++i) {
+		prev_vram_start[i] = cur_vram_start[i];
+	}
+}
+
+void write_char(int row, int col, unsigned char ch) {
+	VRAM[MUL80(row) + col] = ch;
+}
+
+void move_to(int row, int col) {
+	scr.row = row;
+	scr.col = col;
+}
+
+void new_line() {
+	scr.col = 0;
+	if (scr.row == 29) {
+		for (int i = 0; i < 29; ++i) {
+			copy_line(i, i + 1);
+		}
+		int *vram = (int *) (MUL80(29) + VRAM_BASE);
+		for (int i = 0; i < 20; ++i) {
+			vram[i] = 0x20202020;
+		}
+	} else {
+		++scr.row;
+	}
+}
+
+void putch(unsigned char ch) {
+	if (ch == '\n') {
+		new_line();
+	} else if (ch == '\r') { 
+		scr.col = 0;
+	} else {
+		if (scr.col == 79) {
+			new_line();
+		}
+		write_char(scr.row, scr.col, ch);
+		++scr.col;
+	}
+}
+
+void clear_screen() {
+	scr.row = 0;
+	scr.col = 0;
+	int *vram = ((int *) VRAM_BASE);
+	for (int i = 0; i < 600; ++i) vram[i] = 0x20202020;
+}
+
+void print_hex(unsigned int counter) {
+	putch('0'); putch('x');
+	for (int i = 7; i >= 0; --i) {
+		unsigned int num = (counter >> (i << 2)) & 0xF;
+		if (num < 10) {
+			putch('0' + num);
+		} else {
+			putch('A' + num - 10);
+		}
+	}
+}
+
+void putstr(const char *s) {
+	while (*s) {
+		putch(*(s++));
+	}
+}
+
+int hc = 1;
+int fast = 0;
+
+void print_timer() {
+	putstr("Hardware timer count limit = ");
+	print_hex(*TIMER_LIMIT);
+	putstr(", enabled = ");
+	print_hex(*TIMER_ENABLED);
+	putch('\n');
+}
+
+void print_uart() {
+	putstr("UART Baud rate = ");
+	print_hex(*UART_BAUDRATE);
+	putch('\n');
+}
+
+void handle_timer() {
+	putstr("Timer trigger times = ");
+	print_hex(hc++);
+	putch('\n');
+	int mode = ((hc & 0x10) >> 4);
+	if (hc == 0x40) {
+		putstr("Disable timer!\n");
+		*TIMER_ENABLED = 0;
+		print_timer();
+		return;
+	}
+	if (fast ^ mode) {
+		putstr("Switch timer frequency\n");
+		if (fast == 0) {
+			*TIMER_LIMIT = 25000000;
+		} else {
+		
+			*TIMER_LIMIT = 100000000;
+		}
+		fast = mode;
+		print_timer();
+	}
+}
+
+void handle_uart() {
+	unsigned int ch = *UART_RECV;
+	*UART_SEND = ch;
+	putstr("UART Recv hex = "); print_hex(ch); putstr(", ch = "); putch(ch); putch('\n');
+}
+
+void trap_handler(void *epc, unsigned int cause) {
+	putstr("Interrupt! EPC = ");
+	print_hex((unsigned int) epc);
+	putstr(", CAUSE = ");
+	print_hex(cause);
+	putch('\n');
+	switch (cause) {
+	case 0x8000000B:
+		handle_uart();
+		break;
+	default:
+		handle_timer();
+		break;
+	}
+}
+extern void enable_interrupt();
+extern unsigned int get_epc();
+int main() {
+	clear_screen();
+	hc = 0;
+	*TIMER_ENABLED = 1;
+	putstr("YatCPU Demo Program ");
+	putch(137);
+	putstr("2021 Howard Lau\n");
+	putstr("Hello, world!\n");
+	putstr("Last EPC = ");
+	print_hex(get_epc());
+	putch('\n');
+	print_timer();
+	print_uart();
+	*((int *) 0x4) = 0xDEADBEEF;
+	unsigned int i = 0;
+	enable_interrupt();
+	for (;;) ;
+}

lab4/csrc/init.S

@@ -0,0 +1,117 @@
+# Copyright 2021 Howard Lau
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+.section .text.init
+.globl _start
+_start:
+  li sp, 0x10000000 # Initialize stack pointer
+  call main   # Jump to main function
+loop:
+  j loop      # Loop forever
+.globl enable_interrupt
+enable_interrupt:
+  la t0, __trap_entry
+  csrrw t1, mtvec, t0 # setup trap vector base
+  li t0, 0x1888
+  csrrw t1, mstatus, t0 # enable interrupt
+  ret
+.globl enable_paging
+enable_paging:
+  li t0, 0x80000005 # ppn << 12 = 0x005000
+  csrw satp, t0
+  ret
+.globl get_mtval
+get_mtval:
+  csrr a0, mtval
+  ret
+
+.globl get_epc
+get_epc:
+  csrr a0, mepc
+  ret
+.weak trap_handler
+tran_handler:
+  ret
+__trap_entry:
+  csrw mscratch, sp
+  addi sp, sp, -128
+  sw ra, 4(sp)
+
+  sw gp, 12(sp)
+  sw tp, 16(sp)
+  sw t0, 20(sp)
+  sw t1, 24(sp)
+  sw t2, 28(sp)
+  sw tp, 32(sp)
+  sw s1, 36(sp)
+  sw a0, 40(sp)
+  sw a1, 44(sp)
+  sw a2, 48(sp)
+  sw a3, 52(sp)
+  sw a4, 56(sp)
+  sw a5, 60(sp)
+  sw a6, 64(sp)
+  sw a7, 68(sp)
+  sw s2, 72(sp)
+  sw s3, 76(sp)
+  sw s4, 80(sp)
+  sw s5, 84(sp)
+  sw s6, 88(sp)
+  sw s7, 92(sp)
+  sw s8, 96(sp)
+  sw s9, 100(sp)
+  sw s10, 104(sp)
+  sw s11, 108(sp)
+  sw t3, 112(sp)
+  sw t4, 116(sp)
+  sw t5, 120(sp)
+  sw t6, 124(sp)
+
+  csrr a0, mepc
+  csrr a1, mcause
+  call trap_handler
+
+  lw ra, 4(sp)
+
+  lw gp, 12(sp)
+  lw tp, 16(sp)
+  lw t0, 20(sp)
+  lw t1, 24(sp)
+  lw t2, 28(sp)
+  lw tp, 32(sp)
+  lw s1, 36(sp)
+  lw a0, 40(sp)
+  lw a1, 44(sp)
+  lw a2, 48(sp)
+  lw a3, 52(sp)
+  lw a4, 56(sp)
+  lw a5, 60(sp)
+  lw a6, 64(sp)
+  lw a7, 68(sp)
+  lw s2, 72(sp)
+  lw s3, 76(sp)
+  lw s4, 80(sp)
+  lw s5, 84(sp)
+  lw s6, 88(sp)
+  lw s7, 92(sp)
+  lw s8, 96(sp)
+  lw s9, 100(sp)
+  lw s10, 104(sp)
+  lw s11, 108(sp)
+  lw t3, 112(sp)
+  lw t4, 116(sp)
+  lw t5, 120(sp)
+  lw t6, 124(sp)
+  csrr sp, mscratch
+  mret

lab4/csrc/link.lds

@@ -0,0 +1,12 @@
+OUTPUT_ARCH( "riscv" )
+ENTRY(_start)
+
+SECTIONS
+{
+  . = 0x00001000;
+  .text : { *(.text.init) *(.text.startup) *(.text) }
+  .data ALIGN(0x1000) : { *(.data*) *(.rodata*) *(.sdata*) }
+  . = 0x00100000;
+  .bss : { *(.bss) }
+  _end = .;
+}

lab4/csrc/mm.h

@@ -0,0 +1,43 @@
+// Copyright 2022 hrpccs
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+typedef unsigned int uint32;
+typedef uint32 pte_t;
+typedef uint32* pagetable_t;
+
+#define PGSIZE 4096 // bytes per page
+#define PGSHIFT 12  // bits of offset within a page
+
+#define PGROUNDUP(sz)  (((sz)+PGSIZE-1) & ~(PGSIZE-1))
+#define PGROUNDDOWN(a) (((a)) & ~(PGSIZE-1))
+
+#define PTE_V (1L << 0) // valid
+#define PTE_R (1L << 1)
+#define PTE_W (1L << 2)
+#define PTE_X (1L << 3)
+#define PTE_U (1L << 4) // 1 -> user can access
+
+// shift a physical address to the right place for a PTE.
+#define PA2PTE(pa) ((((uint32)pa) >> 12) << 10)
+
+#define PTE2PA(pte) (((pte) >> 10) << 12)
+
+#define PTE_FLAGS(pte) ((pte) & 0x3FF)
+
+// extract the two 10-bit page table indices from a virtual address.
+#define PXMASK          0x3FF // 10 bits
+#define PXSHIFT(level)  (PGSHIFT+(10*(level)))
+#define PX(level, va) ((((uint32) (va)) >> PXSHIFT(level)) & PXMASK)
+
+#define MAXVA (1L << (10 + 10 + 12))

lab4/csrc/mmio.S

@@ -0,0 +1,24 @@
+# Copyright 2021 Howard Lau
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+.globl _start
+_start:
+  li a0, 0x80000000
+  lw t0, 4(a0)
+  li a1, 0xBEEF
+  sw a1, 4(a0)
+  nop
+  lw t1, 4(a0)
+loop:
+  j loop

lab4/csrc/mmio.h

@@ -0,0 +1,33 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#define VRAM_BASE 0x20000000
+#define VRAM ((volatile unsigned char *) VRAM_BASE)
+#define TIMER_BASE 0x80000000
+#define TIMER_LIMIT ((volatile unsigned int *) (TIMER_BASE + 4))
+#define TIMER_ENABLED ((volatile unsigned int *) (TIMER_BASE + 8))
+#define UART_BASE 0x40000000
+#define UART_BAUDRATE ((volatile unsigned int *) (UART_BASE + 4))
+#define UART_RECV ((volatile unsigned int *) (UART_BASE + 12))
+#define UART_SEND ((volatile unsigned int *) (UART_BASE + 16))
+//remap the mmio to reduce memory usage of page table
+#define VA_VRAM_BASE 0x00100000
+#define VA_VRAM ((volatile unsigned char *) VA_VRAM_BASE)
+#define VA_TIMER_BASE 0x00200000
+#define VA_TIMER_LIMIT ((volatile unsigned int *) (VA_TIMER_BASE + 4))
+#define VA_TIMER_ENABLED ((volatile unsigned int *) (VA_TIMER_BASE + 8))
+#define VA_UART_BASE 0x00300000
+#define VA_UART_BAUDRATE ((volatile unsigned int *) (VA_UART_BASE + 4))
+#define VA_UART_RECV ((volatile unsigned int *) (VA_UART_BASE + 12))
+#define VA_UART_SEND ((volatile unsigned int *) (VA_UART_BASE + 16))

lab4/csrc/paging.c

@@ -0,0 +1,191 @@
+// # Copyright 2022 hrpccs
+// #
+// # Licensed under the Apache License, Version 2.0 (the "License");
+// # you may not use this file except in compliance with the License.
+// # You may obtain a copy of the License at
+// #
+// #     http://www.apache.org/licenses/LICENSE-2.0
+// #
+// # Unless required by applicable law or agreed to in writing, software
+// # distributed under the License is distributed on an "AS IS" BASIS,
+// # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// # See the License for the specific language governing permissions and
+// # limitations under the License.
+
+#include "mm.h"
+#include "mmio.h"
+
+
+
+#define SCREEN_COLS 80
+#define SCREEN_ROWS 30
+#define INT_TIMER_LIMIT 50000000
+#define PAGEDIR_BASE 0x5000
+
+typedef unsigned int uint32;
+typedef uint32 pte_t;
+typedef uint32* pagetable_t;
+
+extern void enable_paging();
+extern void enable_interrupt();
+extern int get_mtval();
+
+int wk_mul(int a, int b) {
+  int r = 0;
+  for (; b; a <<= 1, b >>= 1)
+    if (b & 1)
+      r += a;
+  return r;
+}
+
+void memoryset(unsigned char *dest,unsigned char num, unsigned int size){
+    for(unsigned int i=0;i<size;i++){
+        dest[i]=num;
+    }
+}
+
+uint32 pm[8]; //板子上有32kb内存，八个页
+uint32 timercount=0;
+void (*putch_at)(int,int,unsigned char);
+
+void __putch_at(int x, int y, unsigned char ch) {
+	VRAM[wk_mul(y,SCREEN_COLS) + x] = ch;
+}
+
+void __vputch_at(int x, int y, unsigned char ch) {
+	VA_VRAM[wk_mul(y,SCREEN_COLS) + x] = ch;
+}
+
+int alloc(){
+    int index = 0;
+    int max = 8;
+    while(index < max){
+        if(pm[index] == 0){
+            pm[index] = 1;
+            break;
+        }
+        index++;
+    }
+    return index == max ? -1 : index;
+}
+
+void map(pagetable_t pgtbl,uint32 va,uint32 pa,int perm){
+    int t;
+    if((pgtbl[PX(1,va)] & PTE_V )!= PTE_V){ //前缀不存在
+        t=alloc(); //申请一个页给前缀页表
+        if(t>=0){
+            int* taddr = (int*)(t<<12);
+            for(int i=0;i<PGSIZE>>2;i++){
+                taddr[i]=0;
+            }
+            pgtbl[PX(1,va)] = PA2PTE(t<<12) | PTE_V;
+        }else{
+            while(1);
+            for(int i=0;i<14;i++){
+                putch_at(i,22,"out of memory!"[i]);
+            }
+            while(1);
+        }
+    }
+    pagetable_t n = (void*)PTE2PA(pgtbl[PX(1,va)]);
+    n[PX(0,va)] = PA2PTE(pa) | perm | PTE_V;
+}
+
+
+void kvminit(){
+    pagetable_t pgtbl = (void*)PAGEDIR_BASE;
+    // memoryset(pgtbl,0,PGSIZE); //后面需要读这个内存，所以先初始化
+    for(int i=0;i<PGSIZE>>2;i++){
+        pgtbl[i]=0;
+    }
+
+    pm[PAGEDIR_BASE >> 12] = 1;
+    pm[0]=1;
+    pm[1]=1;
+    pm[2]=1;
+    pm[3]=1;
+    pm[4]=1;
+    //create pte mmap for text
+    pgtbl[1023] =  PA2PTE(PAGEDIR_BASE) | PTE_R | PTE_W;
+    map(pgtbl,PAGEDIR_BASE,PAGEDIR_BASE,PTE_R | PTE_W);
+    map(pgtbl,0x0,0x0, PTE_W | PTE_R ); //kernel stack
+    map(pgtbl,0x1000,0x1000, PTE_W | PTE_R | PTE_X ); //
+    map(pgtbl,0x2000,0x2000, PTE_W | PTE_R | PTE_X ); //
+    map(pgtbl,0x3000,0x3000, PTE_W | PTE_R | PTE_X ); //
+    map(pgtbl,0x4000,0x4000, PTE_W | PTE_R | PTE_X ); //
+    map(pgtbl,VA_VRAM_BASE,VRAM_BASE, PTE_W | PTE_R ); //
+    map(pgtbl,VA_VRAM_BASE + PGSIZE,VRAM_BASE + PGSIZE, PTE_W | PTE_R);
+    map(pgtbl,VA_UART_BASE,UART_BASE, PTE_W | PTE_R ); //
+    map(pgtbl,VA_TIMER_BASE,TIMER_BASE, PTE_W | PTE_R ); //
+}
+
+void clear_screen() {
+	int *vram = ((int *) VRAM_BASE);
+	for (int i = 0; i < 600; ++i) vram[i] = 0x20202020;
+}
+
+void trap_handler(void *epc, unsigned int cause) {
+	if (cause == 10 || cause == 15 || cause == 13) {
+        for(int i=0;i<39;i++){
+            putch_at(i,4,"A not handled page fault caused by : 0x"[i]);
+        }
+        int mtval = get_mtval();
+        char ch;
+        for (int i = 0; i < 8; ++i) {
+            unsigned int mask = 0xF << (i * 4);
+            unsigned int num = (mtval & mask) >> (i * 4);
+            if(num >= 10){
+                ch = num - 10 + 'A';
+            }else{
+                ch = num + '0';
+            }
+		    putch_at(39+7-i,4,ch);
+	    }
+        while(1); //目前还没有处理page-fault，因为还没有建立完整的映射。
+	} else if(cause == 0x80000007){
+        for(int i=0;i<16;i++){
+            putch_at(i,3,"timer count : 0x"[i]);
+        }
+        char ch;
+        for (int i = 0; i < 8; ++i) {
+            unsigned int mask = 0xF << (i * 4);
+            unsigned int num = (timercount & mask) >> (i * 4);
+            if(num >= 10){
+                ch = num - 10 + 'A';
+            }else{
+                ch = num + '0';
+            }
+		    putch_at(16+7-i,3,ch);
+	    }
+        timercount += 1;
+
+    }
+}
+
+int main(){
+    putch_at = __putch_at;
+    for(int i=0;i<8;i++){
+        pm[i] = 0;
+    }
+    timercount = 0;
+    clear_screen();
+    for(int i=0;i<19;i++){
+        putch_at(i,0,"print before paging"[i]);
+    }
+    kvminit();
+    putch_at = __vputch_at;
+    enable_paging();
+    for(int i=0;i<18;i++){
+        putch_at(i,1,"print after paging"[i]);
+    }
+    enable_interrupt();
+    *VA_TIMER_ENABLED = 1;
+    *VA_TIMER_LIMIT = INT_TIMER_LIMIT;
+
+    while(1){
+        if(timercount == 0x20){
+            *(int*)0x11415 = 1130;
+        }
+    }
+    for(;;);
+}

lab4/csrc/quicksort.c

@@ -0,0 +1,50 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+void quicksort(int *arr, int l, int r) {
+  if (l >= r) return;
+  int pivot = arr[l];
+  int i = l, j = r;
+  while (i < j) {
+    while(arr[j] >= pivot && i < j) --j;
+    arr[i] = arr[j];
+    while(arr[i] < pivot && i < j) ++i;
+    arr[j] = arr[i];
+  }
+  arr[i] = pivot;
+  quicksort(arr, l, i - 1);
+  quicksort(arr, i + 1, r);
+}
+
+int main() {
+  int nums[10];
+
+  nums[0] = 6;
+  nums[1] = 2;
+  nums[2] = 4;
+  nums[3] = 5;
+  nums[4] = 3;
+  nums[5] = 1;
+  nums[6] = 0;
+  nums[7] = 9;
+  nums[8] = 7;
+  nums[9] = 8;
+
+
+  quicksort(nums, 0, 9);
+
+  for (int i = 1; i <= 10; ++i) {
+    *(int *)(i * 4) = nums[i - 1];
+  }
+}

lab4/csrc/say_goodbye.c

@@ -0,0 +1,44 @@
+
+void uart_send_char(char c)
+{
+  *((volatile unsigned int *) (0x40000010)) = c;
+  // *((volatile unsigned int *) (0x40000000)) = c;
+}
+
+
+void waste_some_time(int cycle) {
+  unsigned int a = 135;
+  while (cycle--) {
+    a++;
+  }
+}
+
+int main() {
+
+    // const char* s = "abcd";
+    const char* s = "Never gonna give you up~ Never gonna let you down~\n\
+    Never gonna run around and~ desert you~\n";
+
+    while (1) {
+      
+
+      // for (int i = 0; i < ; i++) {
+      //   uart_send_char(s[i]);
+      //   waste_some_time(100);
+      // }
+
+      const char *p = s;
+      while (*p != 0)
+      {
+        uart_send_char(*p);
+        p++;
+        waste_some_time(100);
+      }
+
+      waste_some_time(200);
+
+      break;  // print once, but pressing CPU reset can print again
+    }
+
+    return 0;
+}

lab4/csrc/sb.S

@@ -0,0 +1,25 @@
+# Copyright 2021 Howard Lau
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+.globl _start
+_start:
+  li a0, 0x4
+  li t0, 0xDEADBEEF
+  sb t0, 0(a0)
+  lw t1, 0(a0)
+  li s2, 0x15
+  sb s2, 1(a0)
+  lw ra, 0(a0)
+loop:
+  j loop

lab4/csrc/tetris.c

@@ -0,0 +1,498 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifdef DEBUG
+#include <stdio.h>
+#endif
+
+#include "mmio.h"
+
+#define FALL_TIMER_LIMIT 50000000
+#define ROWS 22
+#define COLS 10
+#define OFFSET_X 28
+#define OFFSET_Y 3
+#define SCREEN_COLS 80
+#define SCREEN_ROWS 30
+
+struct block {
+	unsigned int shape[3];
+	unsigned int xywh;
+};
+
+struct block current;
+
+unsigned int score;
+
+unsigned char *board;
+
+#ifdef DEBUG
+unsigned char screen[SCREEN_COLS * SCREEN_ROWS];
+#endif
+
+int wk_mul(int a, int b) {
+  int r = 0;
+  for (; b; a <<= 1, b >>= 1)
+    if (b & 1)
+      r += a;
+  return r;
+}
+
+unsigned int make_xywh(unsigned int x, unsigned int y, unsigned int w, unsigned int h) {
+	return (x << 12) | (y << 4) | (w << 2) | h;
+}
+
+void init_block(struct block *block, int type, int x, int y) {
+	int w = 0; int h = 0;
+	block->shape[0] = block->shape[1] = block->shape[2] = 0;
+	switch(type) {
+	case 0: // I
+		block->shape[0] = 0xF;
+		w = 3; h = 0;
+	break;
+	case 1: // O
+		block->shape[0] = 0x3;
+		block->shape[1] = 0x3;
+		w = 1; h = 1;
+	break;
+	case 2: // J
+		block->shape[0] = 0x4;
+		block->shape[1] = 0x7;
+		w = 2; h = 1;
+		break;
+	case 3: // T
+		block->shape[0] = 0x2;
+		block->shape[1] = 0x7;
+		w = 2; h = 1;
+		break;
+	case 4: // L
+		block->shape[0] = 0x1;
+		block->shape[1] = 0x7;
+		w = 2; h = 1;
+		break;
+	case 5: // Z
+		block->shape[0] = 0x6;
+		block->shape[1] = 0x3;
+		w = 2; h = 1;
+		break;
+	case 6: // S
+		block->shape[0] = 0x3;
+		block->shape[1] = 0x6;
+		w = 2; h = 1;
+		break;
+	}
+	block->xywh = make_xywh(x, y, w, h);
+}
+
+unsigned int get_shape(struct block *block, unsigned int r, unsigned int c) {
+	return (block->shape[r] & (1 << c)) >> c;
+}
+
+unsigned int check_bounds(struct block *block) {
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xC) >> 2;
+	unsigned int y = (xywh & 0xFF0) >> 4;
+	unsigned int x = (xywh & 0xF000) >> 12;
+	if (x < 0 || x + w >= COLS) return 0;
+	if (y < 0 || y + h >= ROWS) return 0;
+	return 1;
+}
+
+void copy_block(struct block *dst, struct block *src) {
+	dst->xywh = src->xywh;
+	dst->shape[0] = src->shape[0];
+	dst->shape[1] = src->shape[1];
+	dst->shape[2] = src->shape[2];
+}
+
+unsigned int check_collision(struct block *block) {	
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xC) >> 2;
+	unsigned int y = (xywh & 0xFF0) >> 4;
+	unsigned int x = (xywh & 0xF000) >> 12;
+	for (int r = 0; r <= h; ++r) {
+		for (int c = 0; c <= w; ++c) {
+                  if (get_shape(block, r, c) &&
+                      board[wk_mul(y + r, COLS) + x + c])
+                    return 0;
+                }
+	}
+	return 1;
+}
+
+void putch_at(int x, int y, unsigned char ch) {
+#ifdef DEBUG
+	screen[wk_mul(OFFSET_Y + y, SCREEN_COLS) + x + OFFSET_X] = ch;
+#else
+	VRAM[wk_mul(OFFSET_Y + y, SCREEN_COLS) + x + OFFSET_X] = ch;
+#endif
+}
+
+void block_move(struct block *block, int dir) {
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xC) >> 2;
+	unsigned int y = (xywh & 0xFF0) >> 4;
+	unsigned int x = (xywh & 0xF000) >> 12;
+	switch(dir) {
+	case 0: // Left
+		x--;
+		break;
+	case 1: // Right
+		x++;
+		break;
+	case 2: // Down
+		y++;
+		break;
+	default:
+		break;
+	}
+	block->xywh = (x << 12) | (y << 4) | (w << 2) | h;
+}
+
+unsigned int move(struct block *block, int dir) {
+	struct block moved;
+	copy_block(&moved, block);
+	block_move(&moved, dir);
+	if (check_bounds(&moved) && check_collision(&moved)) {
+		copy_block(block, &moved);
+		return 1;
+	}
+	return 0;
+}
+
+void block_rotate(struct block *block, unsigned int clock) {
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xC) >> 2;
+	unsigned int y = (xywh & 0xFF0) >> 4;
+	unsigned int x = (xywh & 0xF000) >> 12;
+	unsigned int xyhw = make_xywh(x, y, h, w);
+	unsigned int shape[3] = {0, 0, 0};
+	if (clock) {
+		for (int r = 0; r <= h; ++r) {
+			for (int c = 0; c <= w; ++c) {
+				shape[c] = shape[c] | (get_shape(block, r, c) << (h - r));
+			}
+		}
+		
+	} else {
+		for (int r = 0; r <= h; ++r) {
+			for (int c = 0; c <= w; ++c) {
+				shape[w - c] = shape[w - c] | (get_shape(block, r, c) << r);
+			}
+		}
+	}
+	block->shape[0] = shape[0];
+	block->shape[1] = shape[1];
+	block->shape[2] = shape[2];
+	block->xywh = xyhw;
+}
+
+
+void rotate(struct block *block, int clock) {
+	struct block rotated;
+	copy_block(&rotated, block);
+	block_rotate(&rotated, clock);
+	if (check_bounds(&rotated) && check_collision(&rotated)) {
+		copy_block(block, &rotated);
+		return;
+	}
+	unsigned int xywh = rotated.xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xc) >> 2;
+	unsigned int y = (xywh & 0xff0) >> 4;
+	unsigned int x = (xywh & 0xf000) >> 12;
+	if (x + w >= COLS) {
+		x = COLS - w - 1;
+	}
+	rotated.xywh = make_xywh(x, y, w, h);
+	if (check_bounds(&rotated) && check_collision(&rotated)) {
+		copy_block(block, &rotated);
+	}
+}
+
+void clear_board() {
+	for (int i = 0, s = wk_mul(ROWS, COLS); i < s; ++i) {
+		board[i] = 0;
+	}
+}
+
+void fix_block(struct block *block) {
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xc) >> 2;
+	unsigned int y = (xywh & 0xff0) >> 4;
+	unsigned int x = (xywh & 0xf000) >> 12;
+#ifdef DEBUG
+	printf("%d %d %d %d\n", x, y, w, h);
+#endif
+	for (int r = 0; r <= h; ++r) {
+		for (int c = 0; c <= w; ++c) {
+			if (get_shape(block, r, c)) {
+				board[wk_mul(y + r, COLS) + x + c] = 1;
+			}
+		}
+	}
+}
+
+void print_score() {
+	int c = 8;
+	putch_at(c++,  -2, 'S');
+	putch_at(c++, -2, 'C');
+	putch_at(c++, -2, 'O');
+	putch_at(c++, -2, 'R');
+	putch_at(c++, -2, 'E');
+	for (int i = 0; i < 5; ++i) {
+		unsigned int mask = 0xF << (i * 4);
+		unsigned int num = (score & mask) >> (i * 4);
+		putch_at(12 - i, -1, num + '0');
+	}
+}
+
+void draw_board() {
+	for (int r = 0; r < ROWS; ++r) {
+		for (int c = 0; c < COLS; ++c) {
+			if (board[wk_mul(r , COLS) + c] == 1) {
+				putch_at((c << 1) + 1, r, '[');
+				putch_at((c << 1) + 2, r, ']');
+			} else {
+				putch_at((c << 1) + 1, r, ' ');
+				putch_at((c << 1)+ 2, r, ' ');
+			}
+		}
+	}	
+	unsigned int xywh = current.xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xc) >> 2;
+	unsigned int y = (xywh & 0xff0) >> 4;
+	unsigned int x = (xywh & 0xf000) >> 12;
+	for (int r = 0; r <= h; ++r) {
+		for (int c = 0; c <= w; ++c) {
+			if (get_shape(&current, r, c)) {
+				putch_at(((c + x)  << 1) + 1, r + y, '[');
+				putch_at(((c + x)  << 1) + 2, r + y, ']');
+			}
+		}
+	}
+	print_score();
+}
+
+
+void add_score(unsigned int delta) {
+	score += delta;
+	for (unsigned int i = 0, carry = 0; i < 32; i += 4) {
+		unsigned int mask = 0xF << i;
+		unsigned int num = (score & mask) >> i;
+		num += carry;
+		if (num >= 10) {
+			carry = 1;
+			num -= 10;
+		} else {
+			carry = 0;
+		}
+		score &= ~(mask);
+		score |= (num << i);
+	}
+}
+
+void check_clear() {
+	unsigned int y = (current.xywh & 0xff0) >> 4;
+	unsigned int h = current.xywh & 0x3;
+	for (int r = y + h; r >= y; --r) {
+		unsigned int count = 0;
+		for (int c = 0; c < COLS; ++c) {
+			if (board[wk_mul(r , COLS) + c]) ++count;
+		}
+		if (count == COLS) {
+			add_score(1);
+			for (int nr = r - 1; nr > 0; --nr) {
+				for (int c = 0; c < COLS; ++c) {
+					board[wk_mul(nr + 1, COLS) + c] = board[wk_mul(nr, COLS) + c];
+				}
+			}
+			++r; ++y;
+		}
+	}
+}
+
+unsigned int rand() {
+	static unsigned int seed = 990315;
+	seed = (wk_mul(1103515245 , seed) + 12345) & 0x7FFFFFFF;
+	return seed;
+}
+
+unsigned int rand_type() {
+	unsigned int type = rand() & 0x7;
+	while (type == 7) {
+		type = rand() & 0x7;
+	}
+	return type;
+}
+
+void fall() {
+	if (move(&current, 2) == 0) {
+		fix_block(&current);
+		check_clear();
+		init_block(&current, rand_type(), 4, 0);
+	}
+}
+
+#ifdef DEBUG
+void print_screen() {
+	for (int r = 0; r < SCREEN_ROWS; ++r) {
+		for (int c = 0; c < SCREEN_COLS; ++c) {
+			printf("%c", screen[wk_mul(r, SCREEN_COLS) + c]);
+		}
+		printf("\n");
+	}
+	printf("\n");
+}
+#endif
+
+void on_input(unsigned int ch) {
+	switch (ch) {
+	case 's':
+		fall();
+		break;
+	case 'a':
+		move(&current, 0);
+		break;
+	case 'd':
+		move(&current, 1);
+		break;
+	case 'j':
+		rotate(&current, 0);
+		break;
+	case 'k':
+		rotate(&current, 1);
+		break;
+	}
+	draw_board();
+#ifdef DEBUG
+	print_screen();
+#endif
+}
+
+void on_timer() {
+	fall();
+	draw_board();
+}
+
+void trap_handler(void *epc, unsigned int cause) {
+	if (cause == 0x80000007) {
+		on_timer();
+	} else if (cause == 0x8000000B){
+		unsigned int ch = *UART_RECV;
+		*UART_SEND = ch;
+		on_input(ch);
+	}
+}
+
+void init() {
+	clear_board();
+	// Draw border
+	for (int r = 0; r < ROWS; ++r) {
+		putch_at(0, r, '|');
+		putch_at(COLS << 1 | 1, r, '|');
+	}
+	for (int c = 0; c <= (COLS << 1 | 1); ++c) {
+		putch_at(c, ROWS, '-');
+	}
+	int c = 8;
+	putch_at(c++, ROWS + 1, 'T');
+	putch_at(c++, ROWS + 1, 'E');
+	putch_at(c++, ROWS + 1, 'T');
+	putch_at(c++, ROWS + 1, 'R');
+	putch_at(c++, ROWS + 1, 'I');
+	putch_at(c++, ROWS + 1, 'S');
+	c = 6;
+	putch_at(c++, ROWS + 3, 'H');
+	putch_at(c++, ROWS + 3, 'o');
+	putch_at(c++, ROWS + 3, 'w');
+	putch_at(c++, ROWS + 3, 'a');
+	putch_at(c++, ROWS + 3, 'r');
+	putch_at(c++, ROWS + 3, 'd');
+	c++;
+	putch_at(c++, ROWS + 3, 'L');
+	putch_at(c++, ROWS + 3, 'a');
+	putch_at(c++, ROWS + 3, 'u');
+	c = 9;
+	putch_at(c++, ROWS + 4, '2');
+	putch_at(c++, ROWS + 4, '0');
+	putch_at(c++, ROWS + 4, '2');
+	putch_at(c++, ROWS + 4, '1');
+	init_block(&current, rand_type(), 4, 0);
+	score = 0;
+	draw_board();
+}
+
+void clear_screen() {
+	int *vram = ((int *) VRAM_BASE);
+	for (int i = 0; i < 600; ++i) vram[i] = 0x20202020;
+}
+
+extern void enable_interrupt();
+
+int main() {
+#ifdef DEBUG
+	unsigned char b[ROWS * COLS] = {0};
+	board = b;
+	for (int i = 0; i < SCREEN_ROWS * SCREEN_COLS; ++i) screen[i] = '%';
+	init();
+#else
+	board = (unsigned char *) 16384;
+	for (int i = 0; i < 16384; i += 4) {
+		*((int*) (board + i)) = 0;
+	}
+	clear_screen();
+	init();
+	*((unsigned int *) 4) = 0xDEADBEEF;
+	enable_interrupt();
+	*TIMER_ENABLED = 1;
+	*TIMER_LIMIT = FALL_TIMER_LIMIT;
+	for (;;);
+#endif
+#ifdef DEBUG
+	on_input('a');
+	on_input('a');
+	on_input('s');
+	on_input('s');
+	on_input('s');
+	for (int i = 21; i >= 0; --i) {
+		on_timer();
+	}
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	for (int i = 21; i >= 0; --i) {
+		on_timer();
+	}
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	for (int i = 21; i >= 0; --i) {
+		on_timer();
+		add_score(10);
+	}
+	print_score();
+	print_screen();
+	return 0;
+#endif
+}

lab4/csrc/tetris_mmu.c

@@ -0,0 +1,568 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifdef DEBUG
+#include <stdio.h>
+#endif
+
+#include "mmio.h"
+#include "mm.h"
+
+#define FALL_TIMER_LIMIT 50000000
+#define ROWS 22
+#define COLS 10
+#define OFFSET_X 28
+#define OFFSET_Y 3
+#define SCREEN_COLS 80
+#define SCREEN_ROWS 30
+
+
+struct block {
+	unsigned int shape[3];
+	unsigned int xywh;
+};
+
+struct block current;
+
+unsigned int score;
+
+unsigned char *board;
+
+
+
+int pm[8]; //板子上有32kb内存，八个页
+int timercount=0;
+// void (*putch_at)(int,int,unsigned char);
+#define PAGEDIR_BASE 0x5000
+
+#ifdef DEBUG
+unsigned char screen[SCREEN_COLS * SCREEN_ROWS];
+#endif
+
+int wk_mul(int a, int b) {
+  int r = 0;
+  for (; b; a <<= 1, b >>= 1)
+    if (b & 1)
+      r += a;
+  return r;
+}
+
+unsigned int make_xywh(unsigned int x, unsigned int y, unsigned int w, unsigned int h) {
+	return (x << 12) | (y << 4) | (w << 2) | h;
+}
+
+void init_block(struct block *block, int type, int x, int y) {
+	int w = 0; int h = 0;
+	block->shape[0] = block->shape[1] = block->shape[2] = 0;
+	switch(type) {
+	case 0: // I
+		block->shape[0] = 0xF;
+		w = 3; h = 0;
+	break;
+	case 1: // O
+		block->shape[0] = 0x3;
+		block->shape[1] = 0x3;
+		w = 1; h = 1;
+	break;
+	case 2: // J
+		block->shape[0] = 0x4;
+		block->shape[1] = 0x7;
+		w = 2; h = 1;
+		break;
+	case 3: // T
+		block->shape[0] = 0x2;
+		block->shape[1] = 0x7;
+		w = 2; h = 1;
+		break;
+	case 4: // L
+		block->shape[0] = 0x1;
+		block->shape[1] = 0x7;
+		w = 2; h = 1;
+		break;
+	case 5: // Z
+		block->shape[0] = 0x6;
+		block->shape[1] = 0x3;
+		w = 2; h = 1;
+		break;
+	case 6: // S
+		block->shape[0] = 0x3;
+		block->shape[1] = 0x6;
+		w = 2; h = 1;
+		break;
+	}
+	block->xywh = make_xywh(x, y, w, h);
+}
+
+unsigned int get_shape(struct block *block, unsigned int r, unsigned int c) {
+	return (block->shape[r] & (1 << c)) >> c;
+}
+
+unsigned int check_bounds(struct block *block) {
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xC) >> 2;
+	unsigned int y = (xywh & 0xFF0) >> 4;
+	unsigned int x = (xywh & 0xF000) >> 12;
+	if (x < 0 || x + w >= COLS) return 0;
+	if (y < 0 || y + h >= ROWS) return 0;
+	return 1;
+}
+
+void copy_block(struct block *dst, struct block *src) {
+	dst->xywh = src->xywh;
+	dst->shape[0] = src->shape[0];
+	dst->shape[1] = src->shape[1];
+	dst->shape[2] = src->shape[2];
+}
+
+unsigned int check_collision(struct block *block) {	
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xC) >> 2;
+	unsigned int y = (xywh & 0xFF0) >> 4;
+	unsigned int x = (xywh & 0xF000) >> 12;
+	for (int r = 0; r <= h; ++r) {
+		for (int c = 0; c <= w; ++c) {
+                  if (get_shape(block, r, c) &&
+                      board[wk_mul(y + r, COLS) + x + c])
+                    return 0;
+                }
+	}
+	return 1;
+}
+
+void putch_at(int x, int y, unsigned char ch) {
+#ifdef DEBUG
+	screen[wk_mul(OFFSET_Y + y, SCREEN_COLS) + x + OFFSET_X] = ch;
+#else
+	VA_VRAM[wk_mul(OFFSET_Y + y, SCREEN_COLS) + x + OFFSET_X] = ch;
+#endif
+}
+
+
+void block_move(struct block *block, int dir) {
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xC) >> 2;
+	unsigned int y = (xywh & 0xFF0) >> 4;
+	unsigned int x = (xywh & 0xF000) >> 12;
+	switch(dir) {
+	case 0: // Left
+		x--;
+		break;
+	case 1: // Right
+		x++;
+		break;
+	case 2: // Down
+		y++;
+		break;
+	default:
+		break;
+	}
+	block->xywh = (x << 12) | (y << 4) | (w << 2) | h;
+}
+
+unsigned int move(struct block *block, int dir) {
+	struct block moved;
+	copy_block(&moved, block);
+	block_move(&moved, dir);
+	if (check_bounds(&moved) && check_collision(&moved)) {
+		copy_block(block, &moved);
+		return 1;
+	}
+	return 0;
+}
+
+void block_rotate(struct block *block, unsigned int clock) {
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xC) >> 2;
+	unsigned int y = (xywh & 0xFF0) >> 4;
+	unsigned int x = (xywh & 0xF000) >> 12;
+	unsigned int xyhw = make_xywh(x, y, h, w);
+	unsigned int shape[3] = {0, 0, 0};
+	if (clock) {
+		for (int r = 0; r <= h; ++r) {
+			for (int c = 0; c <= w; ++c) {
+				shape[c] = shape[c] | (get_shape(block, r, c) << (h - r));
+			}
+		}
+		
+	} else {
+		for (int r = 0; r <= h; ++r) {
+			for (int c = 0; c <= w; ++c) {
+				shape[w - c] = shape[w - c] | (get_shape(block, r, c) << r);
+			}
+		}
+	}
+	block->shape[0] = shape[0];
+	block->shape[1] = shape[1];
+	block->shape[2] = shape[2];
+	block->xywh = xyhw;
+}
+
+
+void rotate(struct block *block, int clock) {
+	struct block rotated;
+	copy_block(&rotated, block);
+	block_rotate(&rotated, clock);
+	if (check_bounds(&rotated) && check_collision(&rotated)) {
+		copy_block(block, &rotated);
+		return;
+	}
+	unsigned int xywh = rotated.xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xc) >> 2;
+	unsigned int y = (xywh & 0xff0) >> 4;
+	unsigned int x = (xywh & 0xf000) >> 12;
+	if (x + w >= COLS) {
+		x = COLS - w - 1;
+	}
+	rotated.xywh = make_xywh(x, y, w, h);
+	if (check_bounds(&rotated) && check_collision(&rotated)) {
+		copy_block(block, &rotated);
+	}
+}
+
+void clear_board() {
+	for (int i = 0, s = wk_mul(ROWS, COLS); i < s; ++i) {
+		board[i] = 0;
+	}
+}
+
+void fix_block(struct block *block) {
+	unsigned int xywh = block->xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xc) >> 2;
+	unsigned int y = (xywh & 0xff0) >> 4;
+	unsigned int x = (xywh & 0xf000) >> 12;
+#ifdef DEBUG
+	printf("%d %d %d %d\n", x, y, w, h);
+#endif
+	for (int r = 0; r <= h; ++r) {
+		for (int c = 0; c <= w; ++c) {
+			if (get_shape(block, r, c)) {
+				board[wk_mul(y + r, COLS) + x + c] = 1;
+			}
+		}
+	}
+}
+
+void print_score() {
+	int c = 8;
+	putch_at(c++,  -2, 'S');
+	putch_at(c++, -2, 'C');
+	putch_at(c++, -2, 'O');
+	putch_at(c++, -2, 'R');
+	putch_at(c++, -2, 'E');
+	for (int i = 0; i < 5; ++i) {
+		unsigned int mask = 0xF << (i * 4);
+		unsigned int num = (score & mask) >> (i * 4);
+		putch_at(12 - i, -1, num + '0');
+	}
+}
+
+void draw_board() {
+	for (int r = 0; r < ROWS; ++r) {
+		for (int c = 0; c < COLS; ++c) {
+			if (board[wk_mul(r , COLS) + c] == 1) {
+				putch_at((c << 1) + 1, r, '[');
+				putch_at((c << 1) + 2, r, ']');
+			} else {
+				putch_at((c << 1) + 1, r, ' ');
+				putch_at((c << 1)+ 2, r, ' ');
+			}
+		}
+	}	
+	unsigned int xywh = current.xywh;
+	unsigned int h = xywh & 0x3;
+	unsigned int w = (xywh & 0xc) >> 2;
+	unsigned int y = (xywh & 0xff0) >> 4;
+	unsigned int x = (xywh & 0xf000) >> 12;
+	for (int r = 0; r <= h; ++r) {
+		for (int c = 0; c <= w; ++c) {
+			if (get_shape(&current, r, c)) {
+				putch_at(((c + x)  << 1) + 1, r + y, '[');
+				putch_at(((c + x)  << 1) + 2, r + y, ']');
+			}
+		}
+	}
+	print_score();
+}
+
+
+void add_score(unsigned int delta) {
+	score += delta;
+	for (unsigned int i = 0, carry = 0; i < 32; i += 4) {
+		unsigned int mask = 0xF << i;
+		unsigned int num = (score & mask) >> i;
+		num += carry;
+		if (num >= 10) {
+			carry = 1;
+			num -= 10;
+		} else {
+			carry = 0;
+		}
+		score &= ~(mask);
+		score |= (num << i);
+	}
+}
+
+void check_clear() {
+	unsigned int y = (current.xywh & 0xff0) >> 4;
+	unsigned int h = current.xywh & 0x3;
+	for (int r = y + h; r >= y; --r) {
+		unsigned int count = 0;
+		for (int c = 0; c < COLS; ++c) {
+			if (board[wk_mul(r , COLS) + c]) ++count;
+		}
+		if (count == COLS) {
+			add_score(1);
+			for (int nr = r - 1; nr > 0; --nr) {
+				for (int c = 0; c < COLS; ++c) {
+					board[wk_mul(nr + 1, COLS) + c] = board[wk_mul(nr, COLS) + c];
+				}
+			}
+			++r; ++y;
+		}
+	}
+}
+
+unsigned int rand() {
+	static unsigned int seed = 990315;
+	seed = (wk_mul(1103515245 , seed) + 12345) & 0x7FFFFFFF;
+	return seed;
+}
+
+unsigned int rand_type() {
+	unsigned int type = rand() & 0x7;
+	while (type == 7) {
+		type = rand() & 0x7;
+	}
+	return type;
+}
+
+void fall() {
+	if (move(&current, 2) == 0) {
+		fix_block(&current);
+		check_clear();
+		init_block(&current, rand_type(), 4, 0);
+	}
+}
+
+#ifdef DEBUG
+void print_screen() {
+	for (int r = 0; r < SCREEN_ROWS; ++r) {
+		for (int c = 0; c < SCREEN_COLS; ++c) {
+			printf("%c", screen[wk_mul(r, SCREEN_COLS) + c]);
+		}
+		printf("\n");
+	}
+	printf("\n");
+}
+#endif
+
+void on_input(unsigned int ch) {
+	switch (ch) {
+	case 's':
+		fall();
+		break;
+	case 'a':
+		move(&current, 0);
+		break;
+	case 'd':
+		move(&current, 1);
+		break;
+	case 'j':
+		rotate(&current, 0);
+		break;
+	case 'k':
+		rotate(&current, 1);
+		break;
+	}
+	draw_board();
+#ifdef DEBUG
+	print_screen();
+#endif
+}
+
+void on_timer() {
+	fall();
+	draw_board();
+}
+
+void trap_handler(void *epc, unsigned int cause) {
+	if (cause == 0x80000007) {
+		on_timer();
+	} else if (cause == 0x8000000B){
+		unsigned int ch = *VA_UART_RECV;
+		*VA_UART_SEND = ch;
+		on_input(ch);
+	}
+}
+
+void init() {
+	clear_board();
+	// Draw border
+	for (int r = 0; r < ROWS; ++r) {
+		putch_at(0, r, '|');
+		putch_at(COLS << 1 | 1, r, '|');
+	}
+	for (int c = 0; c <= (2 << COLS | 1); ++c) {
+		putch_at(c, ROWS, '-');
+	}
+	int c = 8; 
+	putch_at(c++, ROWS + 1, 'B');
+	putch_at(c++, ROWS + 1, 'e');
+	putch_at(c++, ROWS + 1, 'g');
+	putch_at(c++, ROWS + 1, 'i');
+	putch_at(c++, ROWS + 1, 'n');
+	putch_at(c++, ROWS + 1, ' ');
+	c = 6;
+	putch_at(c++, ROWS + 3, 'P');
+	putch_at(c++, ROWS + 3, 'a');
+	putch_at(c++, ROWS + 3, 'g');
+	putch_at(c++, ROWS + 3, 'i');
+	putch_at(c++, ROWS + 3, 'n');
+	putch_at(c++, ROWS + 3, 'g');
+	c++;
+	putch_at(c++, ROWS + 3, 'h');
+	putch_at(c++, ROWS + 3, 'r');
+	putch_at(c++, ROWS + 3, 'p');
+	c = 9;
+	putch_at(c++, ROWS + 4, '2');
+	putch_at(c++, ROWS + 4, '0');
+	putch_at(c++, ROWS + 4, '2');
+	putch_at(c++, ROWS + 4, '2');
+	init_block(&current, rand_type(), 4, 0);
+	score = 0;
+	draw_board();
+}
+
+int alloc(){
+    int index = 0;
+    int max = 8;
+    while(index < max){
+        if(pm[index] == 0){
+            pm[index] = 1;
+            break;
+        }
+        index++;
+    }
+    return index == max ? -1 : index;
+}
+
+int map(pagetable_t pgtbl,uint32 va,uint32 pa,int perm){
+    int t;
+    if((pgtbl[PX(1,va)] & PTE_V )!= PTE_V){ //前缀不存在
+        t=alloc(); //申请一个页给前缀页表
+        if(t>=0){
+            pgtbl[PX(1,va)] = PA2PTE(t<<12) | PTE_V;
+        }else{
+			return -1;
+		}
+    }
+    int* n = (void*)PTE2PA(pgtbl[PX(1,va)]);
+    n[PX(0,va)] = PA2PTE(pa) | perm | PTE_V;
+	return 0;
+}
+
+void kvminit(){
+	//init global valuable
+	for(int i=0;i<8;i++){
+        pm[i] = 0;
+    }
+    timercount = 0;
+
+    pagetable_t pgtbl = (void*)PAGEDIR_BASE;
+    // memoryset(pgtbl,0,PGSIZE); //后面需要读这个内存，所以先初始化
+    for(int i=0;i<PGSIZE>>2;i++){
+        pgtbl[i]=0;
+    }
+
+    pm[PAGEDIR_BASE >> 12] = 1;
+    pm[0]=1;
+    pm[1]=1;
+    pm[2]=1;
+    pm[3]=1;
+    pm[4]=1;
+    //create pte mmap for text
+    map(pgtbl,PAGEDIR_BASE,PAGEDIR_BASE,PTE_R | PTE_W);
+    map(pgtbl,0x0,0x0, PTE_W | PTE_R ); //kernel stack
+    map(pgtbl,0x1000,0x1000, PTE_W | PTE_R | PTE_X ); //
+    map(pgtbl,0x2000,0x2000, PTE_W | PTE_R | PTE_X ); //
+    map(pgtbl,0x3000,0x3000, PTE_W | PTE_R | PTE_X ); //
+    map(pgtbl,0x4000,0x4000, PTE_W | PTE_R | PTE_X ); //
+    map(pgtbl,VA_VRAM_BASE,VRAM_BASE, PTE_W | PTE_R ); //
+    map(pgtbl,VA_VRAM_BASE + PGSIZE,VRAM_BASE + PGSIZE, PTE_W | PTE_R);
+    map(pgtbl,VA_UART_BASE,UART_BASE, PTE_W | PTE_R ); //
+    map(pgtbl,VA_TIMER_BASE,TIMER_BASE, PTE_W | PTE_R ); //
+}
+
+void clear_screen() {
+	int *vram = ((int *) VA_VRAM_BASE);
+	for (int i = 0; i < 600; ++i) vram[i] = 0x20202020;
+}
+
+extern void enable_interrupt();
+extern void enable_paging();
+
+int main() {
+#ifdef DEBUG
+	unsigned char b[ROWS * COLS] = {0};
+	board = b;
+	for (int i = 0; i < SCREEN_ROWS * SCREEN_COLS; ++i) screen[i] = '%';
+	init();
+#else
+	kvminit();
+	enable_paging();
+	board = (unsigned char *) 16640; //0x4100
+	clear_screen();
+	init();
+	*((unsigned int *) 4) = 0xDEADBEEF;
+	enable_interrupt();
+	*VA_TIMER_ENABLED = 1;
+	*VA_TIMER_LIMIT = FALL_TIMER_LIMIT;
+	for (;;);
+#endif
+#ifdef DEBUG
+	on_input('a');
+	on_input('a');
+	on_input('s');
+	on_input('s');
+	on_input('s');
+	for (int i = 21; i >= 0; --i) {
+		on_timer();
+	}
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	for (int i = 21; i >= 0; --i) {
+		on_timer();
+	}
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	on_input('d');
+	for (int i = 21; i >= 0; --i) {
+		on_timer();
+		add_score(10);
+	}
+	print_score();
+	print_screen();
+	return 0;
+#endif
+}

lab4/csrc/toolchain.cmake

@@ -0,0 +1,20 @@
+set(CMAKE_SYSTEM_NAME Generic)
+set(CMAKE_SYSTEM_PROCESSOR riscv32)
+
+set(triple riscv32-unknown-elf)
+
+set(CMAKE_C_COMPILER clang)
+set(CMAKE_C_COMPILER_TARGET ${triple})
+set(CMAKE_CXX_COMPILER clang++)
+set(CMAKE_CXX_COMPILER_TARGET ${triple})
+set(CMAKE_ASM_COMPILER clang)
+set(CMAKE_ASM_COMPILER_TARGET ${triple})
+set(CMAKE_AR llvm-ar CACHE FILEPATH "Archiver")
+set(CMAKE_OBJCOPY llvm-objcopy)
+
+set(CMAKE_C_FLAGS_INIT "-mno-relax")
+set(CMAKE_CXX_FLAGS_INIT "-mno-relax")
+set(CMAKE_ASM_FLAGS_INIT "-mno-relax")
+set(CMAKE_EXE_LINKER_FLAGS_INIT "-fuse-ld=lld -nostdlib -static -mno-relax")
+set(CMAKE_MODULE_LINKER_FLAGS_INIT "-fuse-ld=lld -nostdlib -static -mno-relax")
+set(CMAKE_SHARED_LINKER_FLAGS_INIT "-fuse-ld=lld -nostdlib -static -mno-relax")

lab4/project/build.properties

@@ -0,0 +1 @@
+sbt.version = 1.9.6

lab4/project/plugins.sbt

@@ -0,0 +1 @@
+logLevel := Level.Warn

lab4/riscv-target/yatcpu/Makefile.include

@@ -0,0 +1,7 @@
+export TARGETDIR ?= riscv-target
+export XLEN = 32
+export RISCV_TARGET = yatcpu
+export RISCV_DEVICE = 
+export RISCV_TARGET_FLAGS = 
+export RISCV_ASSERT = 0
+JOBS = -j1

lab4/riscv-target/yatcpu/device/rv32i_m/I/Makefile.include

@@ -0,0 +1,54 @@
+TARGET_SIM ?= verilog/verilator/obj_dir/VTop
+TARGET_FLAGS ?= $(RISCV_TARGET_FLAGS)
+ifeq ($(shell command -v $(TARGET_SIM) 2> /dev/null),)
+    $(error Target simulator executable '$(TARGET_SIM)` not found)
+endif
+
+RISCV_PREFIX   ?= riscv64-unknown-elf-
+RISCV_GCC      ?= $(RISCV_PREFIX)gcc
+RISCV_OBJDUMP  ?= $(RISCV_PREFIX)objdump
+RISCV_OBJCOPY  ?= $(RISCV_PREFIX)objcopy
+RISCV_GCC_OPTS ?= -g -static -mcmodel=medany -fvisibility=hidden -nostdlib -nostartfiles $(RVTEST_DEFINES)
+
+COMPILE_CMD = $$(RISCV_GCC) $(1) $$(RISCV_GCC_OPTS) \
+							-I$(ROOTDIR)/riscv-test-suite/env/ \
+							-I$(TARGETDIR)/$(RISCV_TARGET)/ \
+							-T$(TARGETDIR)/$(RISCV_TARGET)/link.ld \
+							$$(<) -o $$@ 
+
+OBJDUMP_CMD = $$(RISCV_OBJDUMP) $$@ -D > $$@.objdump; \
+					$$(RISCV_OBJDUMP) $$@ --source > $$@.debug; \
+                    $$(RISCV_OBJDUMP) -t $$@ | grep " begin_signature$$$$" | awk '{ print $$$$1 }' > $$@.begin_signature; \
+                    $$(RISCV_OBJDUMP) -t $$@ | grep " end_signature$$$$" | awk '{ print $$$$1 }' > $$@.end_signature; \
+                    $$(RISCV_OBJDUMP) -t $$@ | grep " tohost$$$$" | awk '{ print $$$$1 }' > $$@.halt \
+
+
+OBJCOPY_CMD = $$(RISCV_OBJCOPY) $$@ -O binary  -j .text -j .data -j .tohost $$@.asmbin
+
+COMPILE_TARGET=\
+				$(COMPILE_CMD); \
+        if [ $$$$? -ne 0 ] ; \
+                then \
+                echo "\e[31m$$(RISCV_GCC) failed for target $$(@) \e[39m" ; \
+                exit 1 ; \
+                fi ; \
+				$(OBJDUMP_CMD); \
+        if [ $$$$? -ne 0 ] ; \
+                then \
+                echo "\e[31m $$(RISCV_OBJDUMP) failed for target $$(@) \e[39m" ; \
+                exit 1 ; \
+                fi ; \
+                $(OBJCOPY_CMD); \
+        if [ $$$$? -ne 0 ] ; \
+                then \
+                echo "\e[31m $$(RISCV_OBJCOPY) failed for target $$(@) \e[39m" ; \
+                exit 1 ; \
+                fi ; \
+    
+RUN_CMD = $(TARGET_SIM) $(TARGET_FLAGS) \
+            -signature 0x$(shell cat $(<).begin_signature) 0x$(shell cat $(<).end_signature) $(*).signature.output \
+            -halt 0x$(shell cat $(<).halt) \
+            -time 1000000 \
+            -instruction $(<).asmbin
+RUN_TARGET = \
+    $(RUN_CMD)

lab4/riscv-target/yatcpu/link.ld

@@ -0,0 +1,12 @@
+OUTPUT_ARCH( "riscv" )
+ENTRY(rvtest_entry_point)
+
+SECTIONS
+{
+  . = 0x00001000;
+  .text : { *(.text.init) *(.text.startup) *(.text) }
+  .data ALIGN(0x1000) : { *(.data*) *(.rodata*) *(.sdata*) }
+  .tohost ALIGN(0x1000) : { *(.tohost) }
+  .bss : { *(.bss) }
+  _end = .;
+}

lab4/riscv-target/yatcpu/model_test.h

@@ -0,0 +1,46 @@
+#ifndef _COMPLIANCE_MODEL_H_
+#define _COMPLIANCE_MODEL_H_
+
+#define ALIGNMENT 2
+
+#define RVMODEL_DATA_SECTION \
+    .pushsection .tohost,"aw",@progbits; \
+    .align 4; .global tohost; tohost: .word 0; \
+    .popsection;
+
+#define RVMODEL_BOOT
+
+#define RVMODEL_HALT \
+    li x1, 0xBABECAFE; \
+    write_tohost: \
+        sw x1, tohost, x0; \
+    loop: j loop
+
+//RV_COMPLIANCE_DATA_BEGIN
+#define RVMODEL_DATA_BEGIN                                              \
+  .align 4; .global begin_signature; begin_signature:
+
+//RV_COMPLIANCE_DATA_END
+#define RVMODEL_DATA_END                                                      \
+  .align 4; .global end_signature; end_signature:  \
+  RVMODEL_DATA_SECTION                                                        \
+
+//RVTEST_IO_INIT
+#define RVMODEL_IO_INIT
+//RVTEST_IO_WRITE_STR
+#define RVMODEL_IO_WRITE_STR(_R, _STR)
+//RVTEST_IO_CHECK
+#define RVMODEL_IO_CHECK()
+//RVTEST_IO_ASSERT_GPR_EQ
+#define RVMODEL_IO_ASSERT_GPR_EQ(_S, _R, _I)
+//RVTEST_IO_ASSERT_SFPR_EQ
+#define RVMODEL_IO_ASSERT_SFPR_EQ(_F, _R, _I)
+//RVTEST_IO_ASSERT_DFPR_EQ
+#define RVMODEL_IO_ASSERT_DFPR_EQ(_D, _R, _I)
+
+#define RVMODEL_SET_MSW_INT
+#define RVMODEL_CLEAR_MSW_INT
+#define RVMODEL_CLEAR_MTIMER_INT
+#define RVMODEL_CLEAR_MEXT_INT
+
+#endif 

lab4/src/main/scala/board/basys3/BCD2Segments.scala

@@ -0,0 +1,54 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package board.basys3
+
+import chisel3._
+import chisel3.util._
+
+class BCD2Segments extends Module {
+  val io = IO(new Bundle {
+    val bcd = Input(UInt(4.W))
+    val segs = Output(UInt(8.W))
+  })
+
+  val bcd = io.bcd
+  val segs = Wire(UInt(8.W))
+
+  segs := MuxLookup(
+    bcd,
+    0xFF.U,
+    IndexedSeq(
+      0.U -> "b10000001".U,
+      1.U -> "b11001111".U,
+      2.U -> "b10010010".U,
+      3.U -> "b10000110".U,
+      4.U -> "b11001100".U,
+      5.U -> "b10100100".U,
+      6.U -> "b10100000".U,
+      7.U -> "b10001111".U,
+      8.U -> "b10000000".U,
+      9.U -> "b10000100".U,
+      10.U -> "b00001000".U,
+      11.U -> "b01100000".U,
+      12.U -> "b00110001".U,
+      13.U -> "b01000010".U,
+      14.U -> "b00110000".U,
+      15.U -> "b00111000".U,
+    )
+  )
+
+  io.segs := segs
+}
+

lab4/src/main/scala/board/basys3/OnboardDigitDisplay.scala

@@ -0,0 +1,32 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package board.basys3
+
+import chisel3._
+
+class OnboardDigitDisplay extends Module {
+  val io = IO(new Bundle {
+    val digit_mask = Output(UInt(4.W))
+  })
+
+  val counter = RegInit(UInt(16.W), 0.U)
+  val digit_mask = RegInit(UInt(4.W), "b0111".U)
+
+  counter := counter + 1.U
+  when(counter === 0.U) {
+    digit_mask := (digit_mask << 1.U).asUInt + digit_mask(3)
+  }
+  io.digit_mask := digit_mask
+}

lab4/src/main/scala/board/basys3/SYSULogo.scala

@@ -0,0 +1,34 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package board.basys3
+
+import chisel3._
+import chisel3.util._
+
+class SYSULogo extends Module {
+  val io = IO(new Bundle {
+    val digit_mask = Input(UInt(4.W))
+    val segs = Output(UInt(8.W))
+  })
+
+  io.segs := MuxLookup(
+    io.digit_mask,
+    "b00100100".U, // "b0111".U, "b1101".U -> S
+    IndexedSeq(
+      "b1011".U -> "b01000100".U, // Y
+      "b1110".U -> "b01000001".U, // U
+    )
+  )
+}

lab4/src/main/scala/board/basys3/SegmentMux.scala

@@ -0,0 +1,42 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package board.basys3
+
+import chisel3._
+import chisel3.util._
+
+class SegmentMux extends Module {
+  val io = IO(new Bundle {
+    val digit_mask = Input(UInt(4.W))
+    val numbers = Input(UInt(16.W))
+    val segs = Output(UInt(8.W))
+  })
+
+
+  val digit = RegInit(UInt(4.W), 0.U)
+  val bcd2segs = Module(new BCD2Segments)
+
+  bcd2segs.io.bcd := digit
+  io.segs := bcd2segs.io.segs
+  digit := MuxLookup(
+    io.digit_mask,
+    io.numbers(3, 0), // "b1110".U
+    IndexedSeq(
+      "b1101".U -> io.numbers(7, 4),
+      "b1011".U -> io.numbers(11, 8),
+      "b0111".U -> io.numbers(15, 12)
+    )
+  )
+}

lab4/src/main/scala/board/basys3/Top.scala

@@ -0,0 +1,143 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package board.basys3
+
+import chisel3._
+import chisel3.experimental.ChiselEnum
+import chisel3.util._
+import riscv._
+import peripheral.{CharacterDisplay, DummySlave, InstructionROM, Memory, ROMLoader, Timer, Uart, VGADisplay}
+import bus.{BusArbiter, BusSwitch}
+import chisel3.stage.{ChiselGeneratorAnnotation, ChiselStage}
+import riscv.core.CPU
+
+object BootStates extends ChiselEnum {
+  val Init, Loading, Finished = Value
+}
+
+class Top extends Module {
+  val binaryFilename = "tetris.asmbin"
+  val io = IO(new Bundle {
+    val switch = Input(UInt(16.W))
+
+    val segs = Output(UInt(8.W))
+    val digit_mask = Output(UInt(4.W))
+
+    val hsync = Output(Bool())
+    val vsync = Output(Bool())
+    val rgb = Output(UInt(12.W))
+    val led = Output(UInt(16.W))
+
+    val tx = Output(Bool())
+    val rx = Input(Bool())
+  })
+  val boot_state = RegInit(BootStates.Init)
+
+  val uart = Module(new Uart(100000000, 115200))
+  io.tx := uart.io.txd
+  uart.io.rxd := io.rx
+
+  val cpu = Module(new CPU)
+  val mem = Module(new Memory(Parameters.MemorySizeInWords))
+  val timer = Module(new Timer)
+  val dummy = Module(new DummySlave)
+  val bus_arbiter = Module(new BusArbiter)
+  val bus_switch = Module(new BusSwitch)
+
+  val instruction_rom = Module(new InstructionROM(binaryFilename))
+  val rom_loader = Module(new ROMLoader(instruction_rom.capacity))
+
+  val vga_display = Module(new VGADisplay)
+  bus_arbiter.io.bus_request(0) := true.B
+
+  bus_switch.io.master <> cpu.io.axi4_channels
+  bus_switch.io.address := cpu.io.bus_address
+  for (i <- 0 until Parameters.SlaveDeviceCount) {
+    bus_switch.io.slaves(i) <> dummy.io.channels
+  }
+  rom_loader.io.load_address := Parameters.EntryAddress
+  rom_loader.io.load_start := false.B
+  rom_loader.io.rom_data := instruction_rom.io.data
+  instruction_rom.io.address := rom_loader.io.rom_address
+  cpu.io.stall_flag_bus := true.B
+  cpu.io.instruction_valid := false.B
+  bus_switch.io.slaves(0) <> mem.io.channels
+  rom_loader.io.channels <> dummy.io.channels
+  switch(boot_state) {
+    is(BootStates.Init) {
+      rom_loader.io.load_start := true.B
+      boot_state := BootStates.Loading
+      rom_loader.io.channels <> mem.io.channels
+    }
+    is(BootStates.Loading) {
+      rom_loader.io.load_start := false.B
+      rom_loader.io.channels <> mem.io.channels
+      when(rom_loader.io.load_finished) {
+        boot_state := BootStates.Finished
+      }
+    }
+    is(BootStates.Finished) {
+      cpu.io.stall_flag_bus := false.B
+      cpu.io.instruction_valid := true.B
+    }
+  }
+  val display = Module(new CharacterDisplay)
+  bus_switch.io.slaves(1) <> display.io.channels
+  bus_switch.io.slaves(2) <> uart.io.channels
+  bus_switch.io.slaves(4) <> timer.io.channels
+
+  cpu.io.interrupt_flag := Cat(uart.io.signal_interrupt, timer.io.signal_interrupt)
+
+  cpu.io.debug_read_address := 0.U
+  mem.io.debug_read_address := 0.U
+
+  io.hsync := vga_display.io.hsync
+  io.vsync := vga_display.io.vsync
+
+  display.io.x := vga_display.io.x
+  display.io.y := vga_display.io.y
+  display.io.video_on := vga_display.io.video_on
+
+  io.rgb := display.io.rgb
+
+  mem.io.debug_read_address := io.switch(15, 1).asUInt << 2
+  io.led := Mux(
+    io.switch(0),
+    mem.io.debug_read_data(31, 16).asUInt,
+    mem.io.debug_read_data(15, 0).asUInt,
+  )
+
+  val onboard_display = Module(new OnboardDigitDisplay)
+  io.digit_mask := onboard_display.io.digit_mask
+
+  val sysu_logo = Module(new SYSULogo)
+  sysu_logo.io.digit_mask := io.digit_mask
+
+  val seg_mux = Module(new SegmentMux)
+  seg_mux.io.digit_mask := io.digit_mask
+  seg_mux.io.numbers := io.led
+
+  io.segs := MuxLookup(
+    io.switch,
+    seg_mux.io.segs,
+    IndexedSeq(
+      0.U -> sysu_logo.io.segs
+    )
+  )
+}
+
+object VerilogGenerator extends App {
+  (new ChiselStage).execute(Array("-X", "verilog", "-td", "verilog/basys3"), Seq(ChiselGeneratorAnnotation(() => new Top)))
+}

lab4/src/main/scala/board/pynq/Top.scala

@@ -0,0 +1,149 @@
+// Copyright 2022 Canbin Huang
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package board.pynq
+
+import bus.{AXI4LiteChannels, AXI4LiteInterface, BusArbiter, BusSwitch}
+import chisel3._
+import chisel3.experimental.ChiselEnum
+import chisel3.stage.{ChiselGeneratorAnnotation, ChiselStage}
+import chisel3.util.{Cat, is, switch}
+import peripheral._
+import riscv.{ImplementationType, Parameters}
+import riscv.core.{CPU, CPUBundle}
+
+object BootStates extends ChiselEnum {
+  val Init, Loading, BusWait, Finished = Value
+}
+
+class Top extends Module {
+  val binaryFilename = "litenes.asmbin"
+  val io = IO(new Bundle() {
+    val hdmi_clk_n = Output(Bool())
+    val hdmi_clk_p = Output(Bool())
+    val hdmi_data_n = Output(UInt(3.W))
+    val hdmi_data_p = Output(UInt(3.W))
+    val hdmi_hpdn = Output(Bool())
+
+    val axi_mem = new AXI4LiteInterface(32, 32)
+
+    val tx = Output(Bool())
+    val rx = Input(Bool())
+
+    val led = Output(UInt(4.W))
+  })
+  val boot_state = RegInit(BootStates.Init)
+  io.led := boot_state.asUInt
+  val uart = Module(new Uart(125000000, 115200))
+  io.tx := uart.io.txd
+  uart.io.rxd := io.rx
+
+  val cpu = Module(new CPU)
+  val mem = Wire(new AXI4LiteChannels(32, 32))
+  val timer = Module(new Timer)
+  val dummy = Module(new DummySlave)
+  val bus_arbiter = Module(new BusArbiter)
+  val bus_switch = Module(new BusSwitch)
+  mem.write_address_channel.AWADDR <> io.axi_mem.AWADDR
+  mem.write_address_channel.AWPROT <> io.axi_mem.AWPROT
+  mem.write_address_channel.AWREADY <> io.axi_mem.AWREADY
+  mem.write_address_channel.AWVALID <> io.axi_mem.AWVALID
+  mem.read_address_channel.ARADDR <> io.axi_mem.ARADDR
+  mem.read_address_channel.ARPROT <> io.axi_mem.ARPROT
+  mem.read_address_channel.ARREADY <> io.axi_mem.ARREADY
+  mem.read_address_channel.ARVALID <> io.axi_mem.ARVALID
+  mem.read_data_channel.RDATA <> io.axi_mem.RDATA
+  mem.read_data_channel.RVALID <> io.axi_mem.RVALID
+  mem.read_data_channel.RRESP <> io.axi_mem.RRESP
+  mem.read_data_channel.RREADY <> io.axi_mem.RREADY
+  mem.write_data_channel.WDATA <> io.axi_mem.WDATA
+  mem.write_data_channel.WVALID <> io.axi_mem.WVALID
+  mem.write_data_channel.WSTRB <> io.axi_mem.WSTRB
+  mem.write_data_channel.WREADY <> io.axi_mem.WREADY
+  mem.write_response_channel.BVALID <> io.axi_mem.BVALID
+  mem.write_response_channel.BRESP <> io.axi_mem.BRESP
+  mem.write_response_channel.BREADY <> io.axi_mem.BREADY
+
+  val instruction_rom = Module(new InstructionROM(binaryFilename))
+  val rom_loader = Module(new ROMLoader(instruction_rom.capacity))
+
+  val hdmi_display = Module(new HDMIDisplay)
+  bus_arbiter.io.bus_request(0) := true.B
+
+  bus_switch.io.master <> cpu.io.axi4_channels
+  bus_switch.io.address := cpu.io.bus_address
+  for (i <- 0 until Parameters.SlaveDeviceCount) {
+    bus_switch.io.slaves(i) <> dummy.io.channels
+  }
+  rom_loader.io.load_address := Parameters.EntryAddress
+  rom_loader.io.load_start := false.B
+  rom_loader.io.rom_data := instruction_rom.io.data
+  instruction_rom.io.address := rom_loader.io.rom_address
+  cpu.io.stall_flag_bus := true.B
+  cpu.io.instruction_valid := false.B
+  rom_loader.io.channels <> dummy.io.channels
+  bus_switch.io.slaves(0) <> mem
+  switch(boot_state) {
+    is(BootStates.Init) {
+      rom_loader.io.load_start := true.B
+      boot_state := BootStates.Loading
+      rom_loader.io.channels <> mem
+      bus_switch.io.slaves(0) <> dummy.io.channels
+    }
+    is(BootStates.Loading) {
+      rom_loader.io.load_start := false.B
+      rom_loader.io.channels <> mem
+      bus_switch.io.slaves(0) <> dummy.io.channels
+      when(rom_loader.io.load_finished) {
+        boot_state := BootStates.BusWait
+      }
+    }
+    is(BootStates.BusWait) {
+      when(!cpu.io.bus_busy) {
+        boot_state := BootStates.Finished
+      }
+    }
+    is(BootStates.Finished) {
+      cpu.io.stall_flag_bus := false.B
+      cpu.io.instruction_valid := true.B
+      rom_loader.io.channels <> dummy.io.channels
+      bus_switch.io.slaves(0) <> mem
+    }
+  }
+
+  val display = Module(new PixelDisplay)
+  bus_switch.io.slaves(1) <> display.io.channels
+  bus_switch.io.slaves(2) <> uart.io.channels
+  bus_switch.io.slaves(4) <> timer.io.channels
+
+  cpu.io.interrupt_flag := uart.io.signal_interrupt ## timer.io.signal_interrupt
+  io.led := uart.io.signal_interrupt ## timer.io.signal_interrupt ## boot_state.asUInt
+
+  cpu.io.debug_read_address := 0.U
+
+  display.io.x := hdmi_display.io.x_next
+  display.io.y := hdmi_display.io.y_next
+  display.io.video_on := hdmi_display.io.video_on
+  hdmi_display.io.rgb := display.io.rgb
+
+  io.hdmi_hpdn := 1.U
+  io.hdmi_data_n := hdmi_display.io.TMDSdata_n
+  io.hdmi_data_p := hdmi_display.io.TMDSdata_p
+  io.hdmi_clk_n := hdmi_display.io.TMDSclk_n
+  io.hdmi_clk_p := hdmi_display.io.TMDSclk_p
+}
+
+object VerilogGenerator extends App {
+  (new ChiselStage).execute(Array("-X", "verilog", "-td", "verilog/pynq"), Seq(ChiselGeneratorAnnotation(() => new Top)))
+}

lab4/src/main/scala/board/verilator/Top.scala

@@ -0,0 +1,71 @@
+// Copyright 2022 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package board.verilator
+
+import bus.{AXI4LiteSlave, AXI4LiteSlaveBundle, BusArbiter, BusSwitch}
+import chisel3._
+import chisel3.stage.{ChiselGeneratorAnnotation, ChiselStage}
+import peripheral.DummySlave
+import riscv.Parameters
+import riscv.core.CPU
+
+class Top extends Module {
+
+  val io = IO(new Bundle {
+    val signal_interrupt = Input(Bool())
+
+    val mem_slave = new AXI4LiteSlaveBundle(Parameters.AddrBits, Parameters.DataBits)
+    val uart_slave = new AXI4LiteSlaveBundle(Parameters.AddrBits, Parameters.DataBits)
+
+    val cpu_debug_read_address = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val cpu_debug_read_data = Output(UInt(Parameters.DataWidth))
+  })
+
+  // Memory is controlled in C++ code
+  val mem_slave = Module(new AXI4LiteSlave(Parameters.AddrBits, Parameters.DataBits))
+  io.mem_slave <> mem_slave.io.bundle
+
+  // UART is controlled in C++ code
+  val uart_slave = Module(new AXI4LiteSlave(Parameters.AddrBits, Parameters.DataBits))
+  io.uart_slave <> uart_slave.io.bundle
+
+  val cpu = Module(new CPU)
+  val dummy = Module(new DummySlave)
+  val bus_arbiter = Module(new BusArbiter)
+  val bus_switch = Module(new BusSwitch)
+
+  bus_arbiter.io.bus_request(0) := true.B
+
+  bus_switch.io.master <> cpu.io.axi4_channels
+  bus_switch.io.address := cpu.io.bus_address
+  for (i <- 0 until Parameters.SlaveDeviceCount) {
+    bus_switch.io.slaves(i) <> dummy.io.channels
+  }
+
+  cpu.io.stall_flag_bus := false.B
+  cpu.io.instruction_valid := true.B
+  bus_switch.io.slaves(0) <> mem_slave.io.channels
+  bus_switch.io.slaves(2) <> uart_slave.io.channels
+
+  cpu.io.interrupt_flag := io.signal_interrupt
+
+  cpu.io.debug_read_address := io.cpu_debug_read_address
+  io.cpu_debug_read_data := cpu.io.debug_read_data
+}
+
+object VerilogGenerator extends App {
+  (new ChiselStage).execute(Array("-X", "verilog", "-td", "verilog/verilator"), Seq(ChiselGeneratorAnnotation(() =>
+    new Top())))
+}

lab4/src/main/scala/bus/AXI4Lite.scala

@@ -0,0 +1,197 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package bus
+
+import chisel3._
+import chisel3.experimental.ChiselEnum
+import chisel3.util._
+import riscv.Parameters
+
+object AXI4Lite {
+  val protWidth = 3
+  val respWidth = 2
+}
+
+class AXI4LiteWriteAddressChannel(addrWidth: Int) extends Bundle {
+
+  val AWVALID = Output(Bool())
+  val AWREADY = Input(Bool())
+  val AWADDR = Output(UInt(addrWidth.W))
+  val AWPROT = Output(UInt(AXI4Lite.protWidth.W))
+
+}
+
+class AXI4LiteWriteDataChannel(dataWidth: Int) extends Bundle {
+  val WVALID = Output(Bool())
+  val WREADY = Input(Bool())
+  val WDATA = Output(UInt(dataWidth.W))
+  val WSTRB = Output(UInt((dataWidth / 8).W))
+}
+
+class AXI4LiteWriteResponseChannel extends Bundle {
+  val BVALID = Input(Bool())
+  val BREADY = Output(Bool())
+  val BRESP = Input(UInt(AXI4Lite.respWidth.W))
+}
+
+class AXI4LiteReadAddressChannel(addrWidth: Int) extends Bundle {
+  val ARVALID = Output(Bool())
+  val ARREADY = Input(Bool())
+  val ARADDR = Output(UInt(addrWidth.W))
+  val ARPROT = Output(UInt(AXI4Lite.protWidth.W))
+}
+
+class AXI4LiteReadDataChannel(dataWidth: Int) extends Bundle {
+  val RVALID = Input(Bool())
+  val RREADY = Output(Bool())
+  val RDATA = Input(UInt(dataWidth.W))
+  val RRESP = Input(UInt(AXI4Lite.respWidth.W))
+}
+
+class AXI4LiteInterface(addrWidth: Int, dataWidth: Int) extends Bundle {
+    val AWVALID = Output(Bool())
+    val AWREADY = Input(Bool())
+    val AWADDR = Output(UInt(addrWidth.W))
+    val AWPROT = Output(UInt(AXI4Lite.protWidth.W))
+    val WVALID = Output(Bool())
+    val WREADY = Input(Bool())
+    val WDATA = Output(UInt(dataWidth.W))
+    val WSTRB = Output(UInt((dataWidth / 8).W))
+    val BVALID = Input(Bool())
+    val BREADY = Output(Bool())
+    val BRESP = Input(UInt(AXI4Lite.respWidth.W))
+    val ARVALID = Output(Bool())
+    val ARREADY = Input(Bool())
+    val ARADDR = Output(UInt(addrWidth.W))
+    val ARPROT = Output(UInt(AXI4Lite.protWidth.W))
+    val RVALID = Input(Bool())
+    val RREADY = Output(Bool())
+    val RDATA = Input(UInt(dataWidth.W))
+    val RRESP = Input(UInt(AXI4Lite.respWidth.W))
+}
+
+class AXI4LiteChannels(addrWidth: Int, dataWidth: Int) extends Bundle {
+  val write_address_channel = new AXI4LiteWriteAddressChannel(addrWidth)
+  val write_data_channel = new AXI4LiteWriteDataChannel(dataWidth)
+  val write_response_channel = new AXI4LiteWriteResponseChannel()
+  val read_address_channel = new AXI4LiteReadAddressChannel(addrWidth)
+  val read_data_channel = new AXI4LiteReadDataChannel(dataWidth)
+}
+
+class AXI4LiteSlaveBundle(addrWidth: Int, dataWidth: Int) extends Bundle {
+  val read = Output(Bool())
+  val write = Output(Bool())
+  val read_data = Input(UInt(dataWidth.W))
+  val read_valid = Input(Bool())
+  val write_data = Output(UInt(dataWidth.W))
+  val write_strobe = Output(Vec(Parameters.WordSize, Bool()))
+  val address = Output(UInt(addrWidth.W))
+}
+
+class AXI4LiteMasterBundle(addrWidth: Int, dataWidth: Int) extends Bundle {
+  val read = Input(Bool())
+  val write = Input(Bool())
+  val read_data = Output(UInt(dataWidth.W))
+  val write_data = Input(UInt(dataWidth.W))
+  val write_strobe = Input(Vec(Parameters.WordSize, Bool()))
+  val address = Input(UInt(addrWidth.W))
+
+  val busy = Output(Bool())
+  val read_valid = Output(Bool())
+  val write_valid = Output(Bool())
+}
+
+object AXI4LiteStates extends ChiselEnum {
+  val Idle, ReadAddr, ReadData, WriteAddr, WriteData, WriteResp = Value
+}
+
+class AXI4LiteSlave(addrWidth: Int, dataWidth: Int) extends Module {
+  val io = IO(new Bundle {
+    val channels = Flipped(new AXI4LiteChannels(addrWidth, dataWidth))
+    val bundle = new AXI4LiteSlaveBundle(addrWidth, dataWidth)
+  })
+  val state = RegInit(AXI4LiteStates.Idle)
+  val addr = RegInit(0.U(dataWidth.W))
+  io.bundle.address := addr
+  val read = RegInit(false.B)
+  io.bundle.read := read
+  val write = RegInit(false.B)
+  io.bundle.write := write
+  val write_data = RegInit(0.U(dataWidth.W))
+  io.bundle.write_data := write_data
+  val write_strobe = RegInit(VecInit(Seq.fill(Parameters.WordSize)(false.B)))
+  io.bundle.write_strobe := write_strobe
+
+  val ARREADY = RegInit(false.B)
+  io.channels.read_address_channel.ARREADY := ARREADY
+  val RVALID = RegInit(false.B)
+  io.channels.read_data_channel.RVALID := RVALID
+  val RRESP = RegInit(0.U(AXI4Lite.respWidth))
+  io.channels.read_data_channel.RRESP := RRESP
+
+  io.channels.read_data_channel.RDATA := io.bundle.read_data
+
+  val AWREADY = RegInit(false.B)
+  io.channels.write_address_channel.AWREADY := AWREADY
+  val WREADY = RegInit(false.B)
+  io.channels.write_data_channel.WREADY := WREADY
+  write_data := io.channels.write_data_channel.WDATA
+  val BVALID = RegInit(false.B)
+  io.channels.write_response_channel.BVALID := BVALID
+  val BRESP = WireInit(0.U(AXI4Lite.respWidth))
+  io.channels.write_response_channel.BRESP := BRESP
+  //lab4(BUS)
+
+}
+
+class AXI4LiteMaster(addrWidth: Int, dataWidth: Int) extends Module {
+  val io = IO(new Bundle {
+    val channels = new AXI4LiteChannels(addrWidth, dataWidth)
+    val bundle = new AXI4LiteMasterBundle(addrWidth, dataWidth)
+  })
+  val state = RegInit(AXI4LiteStates.Idle)
+  io.bundle.busy := state =/= AXI4LiteStates.Idle
+
+  val addr = RegInit(0.U(dataWidth.W))
+  val read_valid = RegInit(false.B)
+  io.bundle.read_valid := read_valid
+  val write_valid = RegInit(false.B)
+  io.bundle.write_valid := write_valid
+  val write_data = RegInit(0.U(dataWidth.W))
+  val write_strobe = RegInit(VecInit(Seq.fill(Parameters.WordSize)(false.B)))
+  val read_data = RegInit(0.U(dataWidth.W))
+
+  io.channels.read_address_channel.ARADDR := 0.U
+  val ARVALID = RegInit(false.B)
+  io.channels.read_address_channel.ARVALID := ARVALID
+  io.channels.read_address_channel.ARPROT := 0.U
+  val RREADY = RegInit(false.B)
+  io.channels.read_data_channel.RREADY := RREADY
+
+  io.bundle.read_data := io.channels.read_data_channel.RDATA
+  val AWVALID = RegInit(false.B)
+  io.channels.write_address_channel.AWADDR := 0.U
+  io.channels.write_address_channel.AWVALID := AWVALID
+  val WVALID = RegInit(false.B)
+  io.channels.write_data_channel.WVALID := WVALID
+  io.channels.write_data_channel.WDATA := write_data
+  io.channels.write_address_channel.AWPROT := 0.U
+  io.channels.write_data_channel.WSTRB := write_strobe.asUInt
+  val BREADY = RegInit(false.B)
+  io.channels.write_response_channel.BREADY := BREADY
+
+  //lab4(BUS)
+
+}

lab4/src/main/scala/bus/BusArbiter.scala

@@ -0,0 +1,40 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package bus
+
+import chisel3._
+import riscv.Parameters
+
+class BusArbiter extends Module {
+  val io = IO(new Bundle {
+    val bus_request = Input(Vec(Parameters.MasterDeviceCount, Bool()))
+    val bus_granted = Output(Vec(Parameters.MasterDeviceCount, Bool()))
+
+    val ctrl_stall_flag = Output(Bool())
+  })
+  val granted = Wire(UInt())
+  // Static Priority Arbitration
+  // Higher number = Higher priority
+  granted := 0.U
+  for (i <- 0 until Parameters.MasterDeviceCount) {
+    when(io.bus_request(i.U)) {
+      granted := i.U
+    }
+  }
+  for (i <- 0 until Parameters.MasterDeviceCount) {
+    io.bus_granted(i.U) := i.U === granted
+  }
+  io.ctrl_stall_flag := !io.bus_granted(0.U)
+}

lab4/src/main/scala/bus/BusSwitch.scala

@@ -0,0 +1,33 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package bus
+
+import chisel3._
+import peripheral.DummyMaster
+import riscv.Parameters
+
+class BusSwitch extends Module {
+  val io = IO(new Bundle {
+    val address = Input(UInt(Parameters.AddrWidth))
+    val slaves = Vec(Parameters.SlaveDeviceCount, new AXI4LiteChannels(Parameters.AddrBits, Parameters.DataBits))
+    val master = Flipped(new AXI4LiteChannels(Parameters.AddrBits, Parameters.DataBits))
+  })
+  val dummy = Module(new DummyMaster)
+  val index = io.address(Parameters.AddrBits - 1, Parameters.AddrBits - Parameters.SlaveDeviceCountBits)
+  for (i <- 0 until Parameters.SlaveDeviceCount) {
+    io.slaves(i) <> dummy.io.channels
+  }
+  io.master <> io.slaves(index)
+}

lab4/src/main/scala/peripheral/CharacterDisplay.scala

@@ -0,0 +1,89 @@
+// Copyright 2022 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import chisel3._
+import bus.{AXI4LiteChannels, AXI4LiteSlave}
+import chisel3.{Bool, Bundle, Flipped, Module, Mux, Output, UInt, Wire}
+import chisel3.util.{MuxLookup, log2Up}
+import peripheral.ScreenInfo.{DisplayHorizontal, DisplayVertical}
+import riscv.Parameters
+
+object GlyphInfo {
+  val glyphWidth = 8
+  val glyphHeight = 16
+  // ASCII printable characters start from here
+  val spaceIndex = 1
+}
+
+object ScreenInfo {
+  val DisplayHorizontal = 640
+  val DisplayVertical = 480
+}
+
+object CharacterBufferInfo {
+  val CharCols = DisplayHorizontal / GlyphInfo.glyphWidth
+  val CharRows = DisplayVertical / GlyphInfo.glyphHeight
+  val Chars = CharCols * CharRows
+}
+
+class CharacterDisplay extends Module {
+  val io = IO(new Bundle() {
+    val channels = Flipped(new AXI4LiteChannels(log2Up(CharacterBufferInfo.Chars), Parameters.DataBits))
+
+    val x = Input(UInt(16.W))
+    val y = Input(UInt(16.W))
+    val video_on = Input(Bool())
+
+    val rgb = Output(UInt(24.W))
+  })
+  val slave = Module(new AXI4LiteSlave(log2Up(CharacterBufferInfo.Chars), Parameters.DataBits))
+  slave.io.channels <> io.channels
+  val mem = Module(new BlockRAM(CharacterBufferInfo.Chars / Parameters.WordSize))
+  slave.io.bundle.read_valid := true.B
+  mem.io.write_enable := slave.io.bundle.write
+  mem.io.write_data := slave.io.bundle.write_data
+  mem.io.write_address := slave.io.bundle.address
+  mem.io.write_strobe := slave.io.bundle.write_strobe
+
+  mem.io.read_address := slave.io.bundle.address
+  slave.io.bundle.read_data := mem.io.read_data
+
+
+  val font_rom = Module(new FontROM)
+  val row = (io.y >> log2Up(GlyphInfo.glyphHeight)).asUInt
+  val col = (io.x >> log2Up(GlyphInfo.glyphWidth)).asUInt
+  val char_index = (row * CharacterBufferInfo.CharCols.U) + col
+  val offset = char_index(1, 0)
+  val ch = Wire(UInt(8.W))
+
+  mem.io.debug_read_address := char_index
+  ch := MuxLookup(
+    offset,
+    0.U,
+    IndexedSeq(
+      0.U -> mem.io.debug_read_data(7, 0).asUInt,
+      1.U -> mem.io.debug_read_data(15, 8).asUInt,
+      2.U -> mem.io.debug_read_data(23, 16).asUInt,
+      3.U -> mem.io.debug_read_data(31, 24).asUInt
+    )
+  )
+  font_rom.io.glyph_index := Mux(ch >= 32.U, ch - 31.U, 0.U)
+  font_rom.io.glyph_y := io.y(log2Up(GlyphInfo.glyphHeight) - 1, 0)
+
+  // White if pixel_on and glyph pixel on
+  val glyph_x = io.x(log2Up(GlyphInfo.glyphWidth) - 1, 0)
+  io.rgb := Mux(io.video_on && font_rom.io.glyph_pixel_byte(glyph_x), 0xFFFFFF.U, 0.U)
+}

lab4/src/main/scala/peripheral/DummyMaster.scala

@@ -0,0 +1,33 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import bus.{AXI4LiteChannels, AXI4LiteMaster}
+import chisel3._
+import riscv.Parameters
+
+// A dummy master that never initiates reads or writes
+class DummyMaster extends Module {
+  val io = IO(new Bundle {
+    val channels = new AXI4LiteChannels(Parameters.AddrBits, Parameters.DataBits)
+  })
+  val master = Module(new AXI4LiteMaster(Parameters.AddrBits, Parameters.DataBits))
+  master.io.channels <> io.channels
+  master.io.bundle.write_strobe := VecInit(Seq.fill(Parameters.WordSize)(false.B))
+  master.io.bundle.write_data := 0.U
+  master.io.bundle.write := false.B
+  master.io.bundle.read := false.B
+  master.io.bundle.address := 0.U
+}

lab4/src/main/scala/peripheral/DummySlave.scala

@@ -0,0 +1,32 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import bus.{AXI4LiteChannels, AXI4LiteSlave}
+import chisel3._
+import riscv.Parameters
+
+// A dummy AXI4 slave that only returns 0 on read
+// and ignores all writes
+class DummySlave extends Module {
+  val io = IO(new Bundle {
+    val channels = Flipped(new AXI4LiteChannels(4, Parameters.DataBits))
+  })
+
+  val slave = Module(new AXI4LiteSlave(Parameters.AddrBits, Parameters.DataBits))
+  slave.io.channels <> io.channels
+  slave.io.bundle.read_valid := true.B
+  slave.io.bundle.read_data := 0xDEADBEEFL.U
+}

lab4/src/main/scala/peripheral/FontROM.scala

@@ -0,0 +1,65 @@
+package peripheral
+
+import chisel3._
+import chisel3.experimental.{ChiselAnnotation, annotate}
+import chisel3.util.experimental.loadMemoryFromFileInline
+import chisel3.{Bundle, Input, Module, Output, SyncReadMem, UInt}
+import firrtl.annotations.MemorySynthInit
+
+import java.io.FileWriter
+import java.nio.file.Paths
+import javax.imageio.ImageIO
+
+class FontROM(fontBitmapFilename: String = "vga_font_8x16.bmp") extends Module {
+  val glyphWidth = GlyphInfo.glyphWidth
+  val glyphHeight = GlyphInfo.glyphHeight
+
+  val io = IO(new Bundle {
+    val glyph_index = Input(UInt(7.W))
+    val glyph_y = Input(UInt(4.W))
+
+    val glyph_pixel_byte = Output(UInt(8.W))
+  })
+
+  annotate(new ChiselAnnotation {
+    override def toFirrtl =
+      MemorySynthInit
+  })
+
+  val (hexTxtPath, glyphCount) = readFontBitmap()
+  val mem = SyncReadMem(glyphCount, UInt(8.W))
+  loadMemoryFromFileInline(mem, hexTxtPath.toString.replaceAll("\\\\", "/"))
+  io.glyph_pixel_byte := mem.read(io.glyph_index * GlyphInfo.glyphHeight.U + io.glyph_y, true.B)
+
+  def readFontBitmap() = {
+    val inputStream = getClass.getClassLoader.getResourceAsStream(fontBitmapFilename)
+    val image = ImageIO.read(inputStream)
+
+    val glyphColumns = image.getWidth() / glyphWidth
+    val glyphRows = image.getHeight / glyphHeight
+    val glyphCount = glyphColumns * glyphRows
+    val glyphs = new Array[UInt](glyphCount * GlyphInfo.glyphHeight)
+
+    for (row <- 0 until glyphRows) {
+      for (col <- 0 until glyphColumns) {
+        for (i <- 0 until glyphHeight) {
+          var lineInt = 0
+          for (j <- 0 until glyphWidth) {
+            if (image.getRGB(col * glyphWidth + j, row * glyphHeight + i) != 0xFFFFFFFF) {
+              lineInt |= (1 << j)
+            }
+          }
+          glyphs((row * glyphColumns + col) * GlyphInfo.glyphHeight + i) = lineInt.U(8.W)
+        }
+      }
+    }
+    val currentDir = System.getProperty("user.dir")
+    val hexTxtPath = Paths.get(currentDir, "verilog", f"${fontBitmapFilename}.txt")
+    val writer = new FileWriter(hexTxtPath.toString)
+    for (i <- glyphs.indices) {
+      writer.write(f"@$i%x\n${glyphs(i).litValue}%02x\n")
+    }
+    writer.close()
+    (hexTxtPath, glyphs.length)
+  }
+}

lab4/src/main/scala/peripheral/HDMIDisplay.scala

@@ -0,0 +1,398 @@
+// Copyright 2022 hrpccs
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import bus.{AXI4LiteChannels, AXI4LiteSlave}
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+class HDMISync extends Module {
+  val io = IO(new Bundle {
+    val hsync = Output(Bool())
+    val vsync = Output(Bool())
+    val video_on = Output(Bool())
+    val p_tick = Output(Bool())
+    val f_tick = Output(Bool())
+    val x = Output(UInt(10.W))
+    val y = Output(UInt(10.W))
+    val x_next = Output(UInt(10.W))
+    val y_next = Output(UInt(10.W))
+  })
+
+  val DisplayHorizontal = ScreenInfo.DisplayHorizontal
+  val DisplayVertical = ScreenInfo.DisplayVertical
+
+  val BorderLeft = 48
+  val BorderRight = 16
+  val BorderTop = 10
+  val BorderBottom = 33
+
+  val RetraceHorizontal = 96
+  val RetraceVertical = 2
+
+  val MaxHorizontal = DisplayHorizontal + BorderLeft + BorderRight + RetraceHorizontal - 1
+  val MaxVertical = DisplayVertical + BorderTop + BorderBottom + RetraceVertical - 1
+
+  val RetraceHorizontalStart = DisplayHorizontal + BorderRight
+  val RetraceHorizontalEnd = RetraceHorizontalStart + RetraceHorizontal - 1
+
+  val RetraceVerticalStart = DisplayVertical + BorderBottom
+  val RetraceVerticalEnd = RetraceVerticalStart + RetraceVertical - 1
+
+  val pixel = RegInit(UInt(3.W), 0.U)
+  val pixel_next = Wire(UInt(3.W))
+  val pixel_tick = Wire(Bool())
+
+  val v_count_reg = RegInit(UInt(10.W), 0.U)
+  val h_count_reg = RegInit(UInt(10.W), 0.U)
+
+  val v_count_next = Wire(UInt(10.W))
+  val h_count_next = Wire(UInt(10.W))
+
+  val vsync_reg = RegInit(Bool(), false.B)
+  val hsync_reg = RegInit(Bool(), false.B)
+
+  val vsync_next = Wire(Bool())
+  val hsync_next = Wire(Bool())
+
+  pixel_next := Mux(pixel === 4.U, 0.U, pixel + 1.U)
+  pixel_tick := pixel === 0.U
+
+  h_count_next := Mux(
+    pixel_tick,
+    Mux(h_count_reg === MaxHorizontal.U, 0.U, h_count_reg + 1.U),
+    h_count_reg
+  )
+
+  v_count_next := Mux(
+    pixel_tick && h_count_reg === MaxHorizontal.U,
+    Mux(v_count_reg === MaxVertical.U, 0.U, v_count_reg + 1.U),
+    v_count_reg
+  )
+
+  hsync_next := h_count_reg >= RetraceHorizontalStart.U && h_count_reg <= RetraceHorizontalEnd.U
+  vsync_next := v_count_reg >= RetraceVerticalStart.U && v_count_reg <= RetraceVerticalEnd.U
+
+  pixel := pixel_next
+  hsync_reg := hsync_next
+  vsync_reg := vsync_next
+  v_count_reg := v_count_next
+  h_count_reg := h_count_next
+
+  io.video_on := h_count_reg < DisplayHorizontal.U && v_count_reg < DisplayVertical.U
+  io.hsync := hsync_reg
+  io.vsync := vsync_reg
+  io.x := h_count_reg
+  io.y := v_count_reg
+  io.x_next := h_count_next
+  io.y_next := v_count_next
+  io.p_tick := pixel_tick
+  io.f_tick := io.x === 0.U && io.y === 0.U
+}
+
+class TMDS_encoder extends Module {
+  val io = IO(new Bundle() {
+    val video_data = Input(UInt(8.W)) //r,g,b,8bit
+    val control_data = Input(UInt(2.W))
+    val video_on = Input(Bool())
+    val TMDS = Output(UInt(10.W))
+  })
+  val Nb1s = PopCount(io.video_data)
+
+  def xorfct(value: UInt): UInt = {
+    val vin = VecInit(value.asBools)
+    val res = VecInit(511.U.asBools)
+    res(0) := vin(0)
+    for(i <- 1 to 7){
+      res(i) := res(i-1) ^ vin(i)
+    }
+    res(8) := 1.U
+    res.asUInt
+  }
+
+  val xored = xorfct(io.video_data)
+
+  def xnorfct(value: UInt): UInt = {
+    val vin = VecInit(value.asBools)
+    val res = VecInit(511.U.asBools)
+    res(0) := vin(0)
+    for(i <- 1 to 7){
+      res(i) := !(res(i-1) ^ vin(i))
+    }
+    res(8) := 0.U
+    res.asUInt
+  }
+
+  val xnored = xnorfct(io.video_data)
+
+  val XNOR = (Nb1s > 4.U(4.W)) || (Nb1s === 4.U(4.W) && io.video_data(0) === 0.U)
+  val q_m = RegInit(0.U(9.W))
+  q_m := Mux(
+    XNOR,
+    xnored,
+    xored
+  )
+
+  val diffSize = 4
+  val diff = RegInit(0.S(diffSize.W))
+  diff := PopCount(q_m).asSInt - 4.S
+
+  val disparitySize = 4
+  val disparityReg = RegInit(0.S(disparitySize.W))
+  val doutReg = RegInit("b1010101011".U(10.W))
+
+  when(io.video_on === false.B) {
+    disparityReg := 0.S
+    doutReg := "b1010101011".U(10.W)
+    switch(io.control_data) {
+      is("b00".U(2.W)) {
+        doutReg := "b1101010100".U(10.W)
+      }
+      is("b01".U(2.W)) {
+        doutReg := "b0010101011".U(10.W)
+      }
+      is("b10".U(2.W)) {
+        doutReg := "b0101010100".U(10.W)
+      }
+    }
+  }.otherwise {
+    when(disparityReg === 0.S || diff === 0.S) {
+      when(q_m(8) === false.B) {
+        doutReg := "b10".U(2.W) ## ~q_m(7, 0)
+        disparityReg := disparityReg - diff
+      }.otherwise {
+        doutReg := "b01".U(2.W) ## q_m(7, 0)
+        disparityReg := disparityReg + diff
+      }
+    }.elsewhen((!diff(diffSize - 1) && !disparityReg(disparitySize - 1))
+      || (diff(diffSize - 1) && disparityReg(disparitySize - 1))) {
+      doutReg := 1.U(1.W) ## q_m(8) ## ~q_m(7, 0)
+      when(q_m(8)) {
+        disparityReg := disparityReg + 1.S - diff
+      }.otherwise {
+        disparityReg := disparityReg - diff
+      }
+    }.otherwise {
+      doutReg := 0.U(1.W) ## q_m
+      when(q_m(8)) {
+        disparityReg := disparityReg + diff
+      }.otherwise {
+        disparityReg := disparityReg - 1.S + diff
+      }
+    }
+  }
+
+  io.TMDS := doutReg
+}
+
+class HDMIDisplay extends Module {
+  val io = IO(new Bundle() {
+    val rgb = Input(UInt(24.W))
+    val x = Output(UInt(16.W))
+    val y = Output(UInt(16.W))
+    val x_next = Output(UInt(16.W))
+    val y_next = Output(UInt(16.W))
+    val video_on = Output(Bool())
+
+    val TMDSclk_p = Output(Bool())
+    val TMDSdata_p = Output(UInt(3.W))
+    val TMDSclk_n = Output(Bool())
+    val TMDSdata_n = Output(UInt(3.W))
+  })
+  val rgb = io.rgb
+  val pixel_clk = Wire(Bool())
+  val hsync = Wire(Bool())
+  val vsync = Wire(Bool())
+  val sync = Module(new HDMISync)
+
+  io.x := sync.io.x
+  io.y := sync.io.y
+  io.x_next := sync.io.x_next
+  io.y_next := sync.io.y_next
+  io.video_on := sync.io.video_on
+
+  hsync := sync.io.hsync
+  vsync := sync.io.vsync
+  pixel_clk := sync.io.p_tick
+
+  // TMDS_PLLVR is a vivado IP core, check it in /verilog/pynq/TMDS_PLLVR.v
+  val serial_clk = Wire(Clock())
+  val pll_lock = Wire(Bool())
+  val tmdspll = Module(new TMDS_PLLVR)
+  val rst = Wire(Reset())
+  tmdspll.io.clkin := pixel_clk.asClock
+  serial_clk := tmdspll.io.clkout
+  pll_lock := tmdspll.io.lock
+  tmdspll.io.reset := reset
+  rst := ~pll_lock
+
+  val tmds = Wire(UInt(3.W))
+  val tmds_clk = Wire(Bool())
+  withClockAndReset(pixel_clk.asClock, rst) {
+    val tmds_channel1 = Wire(UInt(10.W))
+    val tmds_channel2 = Wire(UInt(10.W))
+    val tmds_channel0 = Wire(UInt(10.W))
+
+    val tmds_green = Module(new TMDS_encoder)
+    val tmds_red = Module(new TMDS_encoder)
+    val tmds_blue = Module(new TMDS_encoder)
+
+    tmds_red.io.video_on := sync.io.video_on
+    tmds_blue.io.video_on := sync.io.video_on
+    tmds_green.io.video_on := sync.io.video_on
+
+    tmds_blue.io.control_data := sync.io.vsync ## sync.io.hsync
+    tmds_green.io.control_data := 0.U
+    tmds_red.io.control_data := 0.U
+
+    tmds_red.io.video_data := rgb(23, 16)
+    tmds_blue.io.video_data := rgb(7, 0)
+    tmds_green.io.video_data := rgb(15, 8)
+
+    tmds_channel0 := tmds_blue.io.TMDS
+    tmds_channel1 := tmds_green.io.TMDS
+    tmds_channel2 := tmds_red.io.TMDS
+
+    val serdesBlue = Module(new Oser10Module())
+    serdesBlue.io.data := tmds_channel0
+    serdesBlue.io.fclk := serial_clk
+
+    val serdesGreen = Module(new Oser10Module())
+    serdesGreen.io.data := tmds_channel1
+    serdesGreen.io.fclk := serial_clk
+
+    val serdesRed = Module(new Oser10Module())
+    serdesRed.io.data := tmds_channel2
+    serdesRed.io.fclk := serial_clk
+
+    tmds := serdesRed.io.q ## serdesGreen.io.q ## serdesBlue.io.q
+
+    //serdesCLk : 25Mhz ,Why not directly use p_tick?
+    //cause Duty Ratio of p_tick is 10% , while which of serdesCLk is 50%
+    val serdesClk = Module(new Oser10Module())
+    serdesClk.io.data := "b1111100000".U(10.W)
+    serdesClk.io.fclk := serial_clk
+
+    tmds_clk := serdesClk.io.q
+
+    val buffDiffBlue = Module(new OBUFDS)
+    buffDiffBlue.io.I := tmds(0)
+    val buffDiffGreen = Module(new OBUFDS)
+    buffDiffGreen.io.I := tmds(1)
+    val buffDiffRed = Module(new OBUFDS)
+    buffDiffRed.io.I := tmds(2)
+    val buffDiffClk = Module(new OBUFDS)
+    buffDiffClk.io.I := tmds_clk
+
+    io.TMDSclk_p := buffDiffClk.io.O
+    io.TMDSclk_n := buffDiffClk.io.OB
+    io.TMDSdata_p := buffDiffRed.io.O ## buffDiffGreen.io.O ## buffDiffBlue.io.O
+    io.TMDSdata_n := buffDiffRed.io.OB ## buffDiffGreen.io.OB ## buffDiffBlue.io.OB
+  }
+}
+
+//----------------------------------------
+//PLL frequency multiplier using BlackBox
+class TMDS_PLLVR extends BlackBox {
+  val io = IO(new Bundle {
+    val clkin = Input(Clock())
+    val reset = Input(Reset())
+    val clkout = Output(Clock())
+    val clkoutd = Output(Clock())
+    val lock = Output(Bool())
+  })
+}
+
+/* OSER10 : serializer 10:1*/
+class OSER10 extends Module {
+  val io = IO(new Bundle {
+    val Q = Output(Bool()) // OSER10 data output signal
+    val D0 = Input(Bool())
+    val D1 = Input(Bool())
+    val D2 = Input(Bool())
+    val D3 = Input(Bool())
+    val D4 = Input(Bool())
+    val D5 = Input(Bool())
+    val D6 = Input(Bool())
+    val D7 = Input(Bool())
+    val D8 = Input(Bool())
+    val D9 = Input(Bool()) //  OSER10 data input signal
+    val PCLK = Input(Clock()) // Primary clock input signal
+    val FCLK = Input(Clock()) // High speed clock input signal
+    val RESET = Input(Reset()) // Asynchronous reset input signal,
+    //active-high.
+  })
+  withClockAndReset(io.FCLK, io.RESET) {
+    val count = RegInit(0.U(4.W))
+    val countnext = Wire(UInt(4.W))
+    io.Q := MuxLookup(
+      count,
+      0.U,
+      IndexedSeq(
+        0.U -> io.D0.asBool,
+        1.U -> io.D1.asBool,
+        2.U -> io.D2.asBool,
+        3.U -> io.D3.asBool,
+        4.U -> io.D4.asBool,
+        5.U -> io.D5.asBool,
+        6.U -> io.D6.asBool,
+        7.U -> io.D7.asBool,
+        8.U -> io.D8.asBool,
+        9.U -> io.D9.asBool
+      )
+    )
+    countnext := Mux(
+      count === 9.U, 0.U, count + 1.U
+    )
+    count := countnext
+  }
+}
+
+class Oser10Module extends Module {
+  val io = IO(new Bundle {
+    val q = Output(Bool())
+    val data = Input(UInt(10.W))
+    val fclk = Input(Clock()) // Fast clock
+  })
+
+  val osr10 = Module(new OSER10())
+  io.q := osr10.io.Q
+  osr10.io.D0 := io.data(0)
+  osr10.io.D1 := io.data(1)
+  osr10.io.D2 := io.data(2)
+  osr10.io.D3 := io.data(3)
+  osr10.io.D4 := io.data(4)
+  osr10.io.D5 := io.data(5)
+  osr10.io.D6 := io.data(6)
+  osr10.io.D7 := io.data(7)
+  osr10.io.D8 := io.data(8)
+  osr10.io.D9 := io.data(9)
+  osr10.io.PCLK := clock
+  osr10.io.FCLK := io.fclk
+  osr10.io.RESET := reset
+}
+
+/* lvds output */
+class OBUFDS extends BlackBox {
+  val io = IO(new Bundle {
+    val O = Output(Bool())
+    val OB = Output(Bool())
+    val I = Input(Bool())
+  })
+}
+//-----------------------------------------
+
+

lab4/src/main/scala/peripheral/InstructionROM.scala

@@ -0,0 +1,68 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import chisel3._
+import chisel3.experimental.{ChiselAnnotation, annotate}
+import chisel3.util.experimental.loadMemoryFromFileInline
+import firrtl.annotations.MemorySynthInit
+import riscv.Parameters
+
+import java.io.{FileInputStream, FileWriter}
+import java.nio.file.{Files, Paths}
+import java.nio.{ByteBuffer, ByteOrder}
+
+class InstructionROM(instructionFilename: String) extends Module {
+  val io = IO(new Bundle {
+    val address = Input(UInt(Parameters.AddrWidth))
+    val data = Output(UInt(Parameters.InstructionWidth))
+  })
+
+  val (instructionsInitFile, capacity) = readAsmBinary(instructionFilename)
+  val mem = SyncReadMem(capacity, UInt(Parameters.InstructionWidth))
+  annotate(new ChiselAnnotation {
+    override def toFirrtl =
+      MemorySynthInit
+  })
+  loadMemoryFromFileInline(mem, instructionsInitFile.toString.replaceAll("\\\\", "/"))
+  io.data := mem.read(io.address, true.B)
+
+  def readAsmBinary(filename: String) = {
+    val inputStream = if (Files.exists(Paths.get(filename))) {
+      Files.newInputStream(Paths.get(filename))
+    } else {
+      getClass.getClassLoader.getResourceAsStream(filename)
+    }
+    var instructions = new Array[BigInt](0)
+    val arr = new Array[Byte](4)
+    while (inputStream.read(arr) == 4) {
+      val instBuf = ByteBuffer.wrap(arr)
+      instBuf.order(ByteOrder.LITTLE_ENDIAN)
+      val inst = BigInt(instBuf.getInt() & 0xFFFFFFFFL)
+      instructions = instructions :+ inst
+    }
+    instructions = instructions :+ BigInt(0x00000013L)
+    instructions = instructions :+ BigInt(0x00000013L)
+    instructions = instructions :+ BigInt(0x00000013L)
+    val currentDir = System.getProperty("user.dir")
+    val exeTxtPath = Paths.get(currentDir, "verilog", f"${instructionFilename}.txt")
+    val writer = new FileWriter(exeTxtPath.toString)
+    for (i <- instructions.indices) {
+      writer.write(f"@$i%x\n${instructions(i)}%08x\n")
+    }
+    writer.close()
+    (exeTxtPath, instructions.length)
+  }
+}

lab4/src/main/scala/peripheral/InterruptController.scala

@@ -0,0 +1,26 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import chisel3._
+import riscv.Parameters
+
+// TODO(howard): implementation
+class InterruptController extends Module {
+  val io = IO(new Bundle {
+    val interrupts = Vec(Parameters.SlaveDeviceCount, Bool())
+    val cpu_interrupt_flag = Output(UInt(Parameters.InterruptFlagWidth))
+  })
+}

lab4/src/main/scala/peripheral/Memory.scala

@@ -0,0 +1,72 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import bus.{AXI4LiteChannels, AXI4LiteSlave}
+import chisel3._
+import riscv.Parameters
+
+// The purpose of this module is to help the synthesis tool recognize
+// our memory as a Block RAM template
+class BlockRAM(capacity: Int) extends Module {
+  val io = IO(new Bundle {
+    val read_address = Input(UInt(Parameters.AddrWidth))
+    val write_address = Input(UInt(Parameters.AddrWidth))
+    val write_data = Input(UInt(Parameters.DataWidth))
+    val write_enable = Input(Bool())
+    val write_strobe = Input(Vec(Parameters.WordSize, Bool()))
+
+    val debug_read_address = Input(UInt(Parameters.AddrWidth))
+
+    val read_data = Output(UInt(Parameters.DataWidth))
+    val debug_read_data = Output(UInt(Parameters.DataWidth))
+  })
+  val mem = SyncReadMem(capacity, Vec(Parameters.WordSize, UInt(Parameters.ByteWidth)))
+  when(io.write_enable) {
+    val write_data_vec = Wire(Vec(Parameters.WordSize, UInt(Parameters.ByteWidth)))
+    for (i <- 0 until Parameters.WordSize) {
+      write_data_vec(i) := io.write_data((i + 1) * Parameters.ByteBits - 1, i * Parameters.ByteBits)
+    }
+    mem.write((io.write_address >> 2.U).asUInt, write_data_vec, io.write_strobe)
+  }
+  io.read_data := mem.read((io.read_address >> 2.U).asUInt, true.B).asUInt
+  io.debug_read_data := mem.read((io.debug_read_address >> 2.U).asUInt, true.B).asUInt
+}
+
+// This module wraps the Block RAM with an AXI4-Lite interface
+class Memory(capacity: Int) extends Module {
+  val io = IO(new Bundle {
+    val channels = Flipped(new AXI4LiteChannels(Parameters.AddrBits, Parameters.DataBits))
+
+    val debug_read_address = Input(UInt(Parameters.AddrWidth))
+    val debug_read_data = Output(UInt(Parameters.DataWidth))
+  })
+
+  val mem = Module(new BlockRAM(capacity))
+  val slave = Module(new AXI4LiteSlave(Parameters.AddrBits, Parameters.DataBits))
+  slave.io.channels <> io.channels
+  slave.io.bundle.read_valid := true.B
+
+  mem.io.write_enable := slave.io.bundle.write
+  mem.io.write_data := slave.io.bundle.write_data
+  mem.io.write_address := slave.io.bundle.address
+  mem.io.write_strobe := slave.io.bundle.write_strobe
+
+  mem.io.read_address := slave.io.bundle.address
+  slave.io.bundle.read_data := mem.io.read_data
+
+  mem.io.debug_read_address := io.debug_read_address
+  io.debug_read_data := mem.io.debug_read_data
+}

lab4/src/main/scala/peripheral/PixelDisplay.scala

@@ -0,0 +1,56 @@
+// Copyright 2022 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import bus.{AXI4LiteChannels, AXI4LiteSlave}
+import chisel3._
+import chisel3.util.log2Up
+import riscv.Parameters
+
+class PixelDisplay extends Module {
+  val io = IO(new Bundle() {
+    val channels = Flipped(new AXI4LiteChannels(32, Parameters.DataBits))
+
+    val x = Input(UInt(16.W))
+    val y = Input(UInt(16.W))
+    val video_on = Input(Bool())
+
+    val rgb = Output(UInt(24.W))
+  })
+  val slave = Module(new AXI4LiteSlave(32, Parameters.DataBits))
+  slave.io.channels <> io.channels
+
+  // 320x240, RGB 565
+  val mem = Module(new BlockRAM(320 * 240 / 2))
+  slave.io.bundle.read_valid := true.B
+  mem.io.write_enable := slave.io.bundle.write
+  mem.io.write_data := slave.io.bundle.write_data
+  mem.io.write_address := slave.io.bundle.address
+  mem.io.write_strobe := slave.io.bundle.write_strobe
+
+  mem.io.read_address := slave.io.bundle.address
+  slave.io.bundle.read_data := mem.io.read_data
+
+
+  val pixel_x = io.x(15, 1).asUInt
+  val pixel_y = io.y(15, 1).asUInt
+  mem.io.debug_read_address := (pixel_y * 320.U + pixel_x) << 1
+
+  val pixel = Mux(pixel_x(0), mem.io.debug_read_data(31, 16), mem.io.debug_read_data(15, 0))
+  val r = pixel(15, 11) ## 0.U(3.W)
+  val g = pixel(10, 5) ## 0.U(2.W)
+  val b = pixel(4, 0) ## 0.U(3.W)
+  io.rgb := Mux(io.video_on, r ## g ## b, 0.U)
+}

lab4/src/main/scala/peripheral/ROMLoader.scala

@@ -0,0 +1,80 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import bus.{AXI4LiteChannels, AXI4LiteMaster}
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+class ROMLoader(capacity: Int) extends Module {
+  val io = IO(new Bundle {
+    val channels = new AXI4LiteChannels(Parameters.AddrBits, Parameters.InstructionBits)
+
+    val rom_address = Output(UInt(Parameters.AddrWidth))
+    val rom_data = Input(UInt(Parameters.InstructionWidth))
+
+    val load_start = Input(Bool())
+    val load_address = Input(UInt(Parameters.AddrWidth))
+    val load_finished = Output(Bool())
+  })
+  val master = Module(new AXI4LiteMaster(Parameters.AddrBits, Parameters.InstructionBits))
+  master.io.channels <> io.channels
+
+  val address = RegInit(0.U(32.W))
+  val valid = RegInit(false.B)
+  val loading = RegInit(false.B)
+
+  master.io.bundle.read := false.B
+  io.load_finished := false.B
+
+  when(io.load_start) {
+    valid := false.B
+    loading := true.B
+    address := 0.U
+  }
+
+  master.io.bundle.write := false.B
+  master.io.bundle.write_data := 0.U
+  master.io.bundle.write_strobe := VecInit(Seq.fill(Parameters.WordSize)(false.B))
+  master.io.bundle.address := 0.U
+
+  when(!loading && !master.io.bundle.busy && address >= (capacity - 1).U) {
+    io.load_finished := true.B
+  }
+  when(loading) {
+    valid := true.B
+    when(!master.io.bundle.busy && !master.io.bundle.write_valid) {
+      when(valid) {
+        master.io.bundle.write := true.B
+        master.io.bundle.write_data := io.rom_data
+        master.io.bundle.write_strobe := VecInit(Seq.fill(Parameters.WordSize)(true.B))
+        master.io.bundle.address := (address << 2.U).asUInt + io.load_address
+      }
+    }
+    when(master.io.bundle.write_valid) {
+      when(address >= (capacity - 1).U) {
+        loading := false.B
+      }.otherwise {
+        loading := true.B
+        address := address + 1.U
+        valid := false.B
+      }
+    }.otherwise {
+      address := address
+    }
+  }
+  io.rom_address := address
+}

lab4/src/main/scala/peripheral/SPI.scala

@@ -0,0 +1,24 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import chisel3._
+import chisel3.util._
+
+class SPI extends Module {
+  val io = IO(new Bundle {
+
+  })
+}

lab4/src/main/scala/peripheral/Timer.scala

@@ -0,0 +1,67 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import bus.{AXI4LiteChannels, AXI4LiteSlave}
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+class Timer extends Module {
+  val io = IO(new Bundle {
+    val channels = Flipped(new AXI4LiteChannels(8, Parameters.DataBits))
+    val signal_interrupt = Output(Bool())
+
+    val debug_limit = Output(UInt(Parameters.DataWidth))
+    val debug_enabled = Output(Bool())
+  })
+  val slave = Module(new AXI4LiteSlave(8, Parameters.DataBits))
+  slave.io.channels <> io.channels
+
+  val count = RegInit(0.U(32.W))
+  val limit = RegInit(100000000.U(32.W))
+  io.debug_limit := limit
+  val enabled = RegInit(true.B)
+  io.debug_enabled := enabled
+
+  slave.io.bundle.read_data := 0.U
+  slave.io.bundle.read_valid := true.B
+  when(slave.io.bundle.read) {
+    slave.io.bundle.read_data := MuxLookup(
+      slave.io.bundle.address,
+      0.U,
+      IndexedSeq(
+        0x4.U -> limit,
+        0x8.U -> enabled.asUInt,
+      )
+    )
+  }
+  when(slave.io.bundle.write) {
+    when(slave.io.bundle.address === 0x4.U) {
+      limit := slave.io.bundle.write_data
+      count := 0.U
+    }.elsewhen(slave.io.bundle.address === 0x8.U) {
+      enabled := slave.io.bundle.write_data =/= 0.U
+    }
+  }
+
+  io.signal_interrupt := enabled && (count >= (limit - 10.U))
+
+  when(count >= limit) {
+    count := 0.U
+  }.otherwise {
+    count := count + 1.U
+  }
+}

lab4/src/main/scala/peripheral/UART.scala

@@ -0,0 +1,211 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import bus.{AXI4LiteChannels, AXI4LiteSlave}
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+class UartIO extends DecoupledIO(UInt(8.W)) {
+}
+
+
+/**
+ * Transmit part of the UART.
+ * A minimal version without any additional buffering.
+ * Use a ready/valid handshaking.
+ */
+class Tx(frequency: Int, baudRate: Int) extends Module {
+  val io = IO(new Bundle {
+    val txd = Output(UInt(1.W))
+    val channel = Flipped(new UartIO())
+
+  })
+
+  val BIT_CNT = ((frequency + baudRate / 2) / baudRate - 1).U
+
+  val shiftReg = RegInit(0x7ff.U)
+  val cntReg = RegInit(0.U(20.W))
+  val bitsReg = RegInit(0.U(4.W))
+
+  io.channel.ready := (cntReg === 0.U) && (bitsReg === 0.U)
+  io.txd := shiftReg(0)
+
+  when(cntReg === 0.U) {
+
+    cntReg := BIT_CNT
+    when(bitsReg =/= 0.U) {
+      val shift = shiftReg >> 1
+      shiftReg := Cat(1.U, shift(9, 0))
+      bitsReg := bitsReg - 1.U
+    }.otherwise {
+      when(io.channel.valid) {
+        shiftReg := Cat(Cat(3.U, io.channel.bits), 0.U) // two stop bits, data, one start bit
+        bitsReg := 11.U
+      }.otherwise {
+        shiftReg := 0x7ff.U
+      }
+    }
+
+  }.otherwise {
+    cntReg := cntReg - 1.U
+  }
+}
+
+/**
+ * Receive part of the UART.
+ * A minimal version without any additional buffering.
+ * Use a ready/valid handshaking.
+ *
+ * The following code is inspired by Tommy's receive code at:
+ * https://github.com/tommythorn/yarvi
+ */
+class Rx(frequency: Int, baudRate: Int) extends Module {
+  val io = IO(new Bundle {
+    val rxd = Input(UInt(1.W))
+    val channel = new UartIO()
+
+  })
+
+  val BIT_CNT = ((frequency + baudRate / 2) / baudRate - 1).U
+  val START_CNT = ((3 * frequency / 2 + baudRate / 2) / baudRate - 1).U
+
+  // Sync in the asynchronous RX data, reset to 1 to not start reading after a reset
+  val rxReg = RegNext(RegNext(io.rxd, 1.U), 1.U)
+
+  val shiftReg = RegInit(0.U(8.W))
+  val cntReg = RegInit(0.U(20.W))
+  val bitsReg = RegInit(0.U(4.W))
+  val valReg = RegInit(false.B)
+
+  when(cntReg =/= 0.U) {
+    cntReg := cntReg - 1.U
+  }.elsewhen(bitsReg =/= 0.U) {
+    cntReg := BIT_CNT
+    shiftReg := Cat(rxReg, shiftReg >> 1)
+    bitsReg := bitsReg - 1.U
+    // the last shifted in
+    when(bitsReg === 1.U) {
+      valReg := true.B
+    }
+  }.elsewhen(rxReg === 0.U) { // wait 1.5 bits after falling edge of start
+    cntReg := START_CNT
+    bitsReg := 8.U
+  }
+
+  when(valReg && io.channel.ready) {
+    valReg := false.B
+  }
+
+  io.channel.bits := shiftReg
+  io.channel.valid := valReg
+}
+
+/**
+ * A single byte buffer with a ready/valid interface
+ */
+class Buffer extends Module {
+  val io = IO(new Bundle {
+    val in = Flipped(new UartIO())
+    val out = new UartIO()
+  })
+
+  val empty :: full :: Nil = Enum(2)
+  val stateReg = RegInit(empty)
+  val dataReg = RegInit(0.U(8.W))
+
+  io.in.ready := stateReg === empty
+  io.out.valid := stateReg === full
+
+  when(stateReg === empty) {
+    when(io.in.valid) {
+      dataReg := io.in.bits
+      stateReg := full
+    }
+  }.otherwise { // full
+    when(io.out.ready) {
+      stateReg := empty
+    }
+  }
+  io.out.bits := dataReg
+}
+
+/**
+ * A transmitter with a single buffer.
+ */
+class BufferedTx(frequency: Int, baudRate: Int) extends Module {
+  val io = IO(new Bundle {
+    val txd = Output(UInt(1.W))
+    val channel = Flipped(new UartIO())
+
+  })
+  val tx = Module(new Tx(frequency, baudRate))
+  val buf = Module(new Buffer)
+
+  buf.io.in <> io.channel
+  tx.io.channel <> buf.io.out
+  io.txd <> tx.io.txd
+}
+
+class Uart(frequency: Int, baudRate: Int) extends Module {
+  val io = IO(new Bundle {
+    val channels = Flipped(new AXI4LiteChannels(8, Parameters.DataBits))
+    val rxd = Input(UInt(1.W))
+    val txd = Output(UInt(1.W))
+
+    val signal_interrupt = Output(Bool())
+  })
+  val interrupt = RegInit(false.B)
+  val rxData = RegInit(0.U)
+  val slave = Module(new AXI4LiteSlave(8, Parameters.DataBits))
+  slave.io.channels <> io.channels
+
+  val tx = Module(new BufferedTx(frequency, baudRate))
+  val rx = Module(new Rx(frequency, baudRate))
+
+  slave.io.bundle.read_data := 0.U
+  slave.io.bundle.read_valid := true.B
+  when(slave.io.bundle.read) {
+    when(slave.io.bundle.address === 0x4.U) {
+      slave.io.bundle.read_data := baudRate.U
+    }.elsewhen(slave.io.bundle.address === 0xC.U) {
+      slave.io.bundle.read_data := rxData
+      interrupt := false.B
+    }
+  }
+
+  tx.io.channel.valid := false.B
+  tx.io.channel.bits := 0.U
+  when(slave.io.bundle.write) {
+    when(slave.io.bundle.address === 0x8.U) {
+      interrupt := slave.io.bundle.write_data =/= 0.U
+    }.elsewhen(slave.io.bundle.address === 0x10.U) {
+      tx.io.channel.valid := true.B
+      tx.io.channel.bits := slave.io.bundle.write_data
+    }
+  }
+
+  io.txd := tx.io.txd
+  rx.io.rxd := io.rxd
+
+  io.signal_interrupt := interrupt
+  rx.io.channel.ready := false.B
+  when(rx.io.channel.valid) {
+    rx.io.channel.ready := true.B
+    rxData := rx.io.channel.bits
+    interrupt := true.B
+  }
+}

lab4/src/main/scala/peripheral/VGADisplay.scala

@@ -0,0 +1,129 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package peripheral
+
+import bus.{AXI4LiteChannels, AXI4LiteSlave}
+import chisel3._
+import chisel3.experimental.{ChiselAnnotation, annotate}
+import chisel3.util._
+import chisel3.util.experimental.loadMemoryFromFileInline
+import firrtl.annotations.MemorySynthInit
+import riscv.Parameters
+
+import java.io.FileWriter
+import java.nio.file.Paths
+import javax.imageio.ImageIO
+
+
+
+
+class VGASync extends Module {
+  val io = IO(new Bundle {
+    val hsync = Output(Bool())
+    val vsync = Output(Bool())
+    val video_on = Output(Bool())
+    val p_tick = Output(Bool())
+    val f_tick = Output(Bool())
+    val x = Output(UInt(10.W))
+    val y = Output(UInt(10.W))
+  })
+
+  val DisplayHorizontal = ScreenInfo.DisplayHorizontal
+  val DisplayVertical = ScreenInfo.DisplayVertical
+
+  val BorderLeft = 48
+  val BorderRight = 16
+  val BorderTop = 10
+  val BorderBottom = 33
+
+  val RetraceHorizontal = 96
+  val RetraceVertical = 2
+
+  val MaxHorizontal = DisplayHorizontal + BorderLeft + BorderRight + RetraceHorizontal - 1
+  val MaxVertical = DisplayVertical + BorderTop + BorderBottom + RetraceVertical - 1
+
+  val RetraceHorizontalStart = DisplayHorizontal + BorderRight
+  val RetraceHorizontalEnd = RetraceHorizontalStart + RetraceHorizontal - 1
+
+  val RetraceVerticalStart = DisplayVertical + BorderBottom
+  val RetraceVerticalEnd = RetraceVerticalStart + RetraceVertical - 1
+
+  val pixel = RegInit(UInt(2.W), 0.U)
+  val pixel_next = Wire(UInt(2.W))
+  val pixel_tick = Wire(Bool())
+
+  val v_count_reg = RegInit(UInt(10.W), 0.U)
+  val h_count_reg = RegInit(UInt(10.W), 0.U)
+
+  val v_count_next = Wire(UInt(10.W))
+  val h_count_next = Wire(UInt(10.W))
+
+  val vsync_reg = RegInit(Bool(), false.B)
+  val hsync_reg = RegInit(Bool(), false.B)
+
+  val vsync_next = Wire(Bool())
+  val hsync_next = Wire(Bool())
+
+  pixel_next := pixel + 1.U
+  pixel_tick := pixel === 0.U
+
+  h_count_next := Mux(
+    pixel_tick,
+    Mux(h_count_reg === MaxHorizontal.U, 0.U, h_count_reg + 1.U),
+    h_count_reg
+  )
+
+  v_count_next := Mux(
+    pixel_tick && h_count_reg === MaxHorizontal.U,
+    Mux(v_count_reg === MaxVertical.U, 0.U, v_count_reg + 1.U),
+    v_count_reg
+  )
+
+  hsync_next := h_count_reg >= RetraceHorizontalStart.U && h_count_reg <= RetraceHorizontalEnd.U
+  vsync_next := v_count_reg >= RetraceVerticalStart.U && v_count_reg <= RetraceVerticalEnd.U
+
+  pixel := pixel_next
+  hsync_reg := hsync_next
+  vsync_reg := vsync_next
+  v_count_reg := v_count_next
+  h_count_reg := h_count_next
+
+  io.video_on := h_count_reg < DisplayHorizontal.U && v_count_reg < DisplayVertical.U
+  io.hsync := hsync_reg
+  io.vsync := vsync_reg
+  io.x := h_count_reg
+  io.y := v_count_reg
+  io.p_tick := pixel_tick
+  io.f_tick := io.x === 0.U && io.y === 0.U
+}
+
+class VGADisplay extends Module {
+  val io = IO(new Bundle() {
+    val rgb = Input(UInt(24.W))
+    val x = Output(UInt(16.W))
+    val y = Output(UInt(16.W))
+    val video_on = Output(Bool())
+
+    val hsync = Output(Bool())
+    val vsync = Output(Bool())
+  })
+
+  val sync = Module(new VGASync)
+  io.hsync := sync.io.hsync
+  io.vsync := sync.io.vsync
+  io.x := sync.io.x
+  io.y := sync.io.y
+  io.video_on := sync.io.y
+}

lab4/src/main/scala/riscv/Parameters.scala

@@ -0,0 +1,58 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv
+
+import chisel3._
+import chisel3.util._
+
+object ImplementationType {
+  val ThreeStage = 0
+  val FiveStage = 1
+}
+
+object Parameters {
+  val AddrBits = 32
+  val AddrWidth = AddrBits.W
+
+  val InstructionBits = 32
+  val InstructionWidth = InstructionBits.W
+  val DataBits = 32
+  val DataWidth = DataBits.W
+  val ByteBits = 8
+  val ByteWidth = ByteBits.W
+  val WordSize = Math.ceil(DataBits / ByteBits).toInt
+
+  val PhysicalRegisters = 32
+  val PhysicalRegisterAddrBits = log2Up(PhysicalRegisters)
+  val PhysicalRegisterAddrWidth = PhysicalRegisterAddrBits.W
+
+  val CSRRegisterAddrBits = 12
+  val CSRRegisterAddrWidth = CSRRegisterAddrBits.W
+
+  val InterruptFlagBits = 32
+  val InterruptFlagWidth = InterruptFlagBits.W
+
+  val HoldStateBits = 3
+  val StallStateWidth = HoldStateBits.W
+
+  val MemorySizeInBytes = 32768
+  val MemorySizeInWords = MemorySizeInBytes / 4
+
+  val EntryAddress = 0x1000.U(Parameters.AddrWidth)
+
+  val MasterDeviceCount = 1
+  val SlaveDeviceCount = 8
+  val SlaveDeviceCountBits = log2Up(Parameters.SlaveDeviceCount)
+}

lab4/src/main/scala/riscv/core/BusBundle.scala

@@ -0,0 +1,32 @@
+// Copyright 2022 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core
+
+import chisel3._
+import riscv.Parameters
+
+class BusBundle extends Bundle {
+  val read = Output(Bool())
+  val address = Output(UInt(Parameters.AddrWidth))
+  val read_data = Input(UInt(Parameters.DataWidth))
+  val read_valid = Input(Bool())
+  val write = Output(Bool())
+  val write_data = Output(UInt(Parameters.DataWidth))
+  val write_strobe = Output(Vec(Parameters.WordSize, Bool()))
+  val write_valid = Input(Bool())
+  val busy = Input(Bool())
+  val request = Output(Bool())
+  val granted = Input(Bool())
+}

lab4/src/main/scala/riscv/core/CPU.scala

@@ -0,0 +1,32 @@
+// Copyright 2022 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core
+
+import chisel3._
+import threestage.{CPU => ThreeStageCPU}
+import fivestage.{CPU => FiveStageCPU}
+import riscv.ImplementationType
+
+class CPU(val implementation: Int = ImplementationType.FiveStage) extends Module {
+  val io = IO(new CPUBundle)
+  implementation match {
+    case ImplementationType.ThreeStage =>
+      val cpu = Module(new ThreeStageCPU)
+      cpu.io <> io
+    case _ =>
+      val cpu = Module(new FiveStageCPU)
+      cpu.io <> io
+  }
+}

lab4/src/main/scala/riscv/core/CPUBundle.scala

@@ -0,0 +1,32 @@
+// Copyright 2022 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core
+
+import bus.{AXI4LiteChannels, AXI4LiteMasterBundle}
+import chisel3._
+import riscv.Parameters
+
+class CPUBundle extends Bundle {
+  val axi4_channels = new AXI4LiteChannels(Parameters.AddrBits, Parameters.DataBits)
+  val bus_address = Output(UInt(Parameters.AddrWidth))
+  val interrupt_flag = Input(UInt(Parameters.InterruptFlagWidth))
+  val stall_flag_bus = Input(Bool())
+  val debug_read_address = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+  val debug_read_data = Output(UInt(Parameters.DataWidth))
+
+  val instruction_valid = Input(Bool())
+  val bus_busy = Output(Bool())
+  val debug = Output(Vec(6, UInt(32.W)))
+}

lab4/src/main/scala/riscv/core/fivestage/ALU.scala

@@ -0,0 +1,70 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.experimental.ChiselEnum
+import chisel3.util._
+import riscv.Parameters
+
+object ALUFunctions extends ChiselEnum {
+  val zero, add, sub, sll, slt, xor, or, and, srl, sra, sltu = Value
+}
+
+class ALU extends Module {
+  val io = IO(new Bundle {
+    val func = Input(ALUFunctions())
+
+    val op1 = Input(UInt(Parameters.DataWidth))
+    val op2 = Input(UInt(Parameters.DataWidth))
+
+    val result = Output(UInt(Parameters.DataWidth))
+  })
+
+  io.result := 0.U
+  switch(io.func) {
+    is(ALUFunctions.add) {
+      io.result := io.op1 + io.op2
+    }
+    is(ALUFunctions.sub) {
+      io.result := io.op1 - io.op2
+    }
+    is(ALUFunctions.sll) {
+      io.result := io.op1 << io.op2(4, 0)
+    }
+    is(ALUFunctions.slt) {
+      io.result := io.op1.asSInt < io.op2.asSInt
+    }
+    is(ALUFunctions.xor) {
+      io.result := io.op1 ^ io.op2
+    }
+    is(ALUFunctions.or) {
+      io.result := io.op1 | io.op2
+    }
+    is(ALUFunctions.and) {
+      io.result := io.op1 & io.op2
+    }
+    is(ALUFunctions.srl) {
+      io.result := io.op1 >> io.op2(4, 0)
+    }
+    is(ALUFunctions.sra) {
+      io.result := (io.op1.asSInt >> io.op2(4, 0)).asUInt
+    }
+    is(ALUFunctions.sltu) {
+      io.result := io.op1 < io.op2
+    }
+  }
+
+}

lab4/src/main/scala/riscv/core/fivestage/ALUControl.scala

@@ -0,0 +1,86 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.util._
+
+class ALUControl extends Module {
+  val io = IO(new Bundle {
+    val opcode = Input(UInt(7.W))
+    val funct3 = Input(UInt(3.W))
+    val funct7 = Input(UInt(7.W))
+
+    val alu_funct = Output(ALUFunctions())
+  })
+
+  io.alu_funct := ALUFunctions.zero
+
+  switch(io.opcode) {
+    is(InstructionTypes.I) {
+      io.alu_funct := MuxLookup(
+        io.funct3,
+        ALUFunctions.zero,
+        IndexedSeq(
+          InstructionsTypeI.addi -> ALUFunctions.add,
+          InstructionsTypeI.slli -> ALUFunctions.sll,
+          InstructionsTypeI.slti -> ALUFunctions.slt,
+          InstructionsTypeI.sltiu -> ALUFunctions.sltu,
+          InstructionsTypeI.xori -> ALUFunctions.xor,
+          InstructionsTypeI.ori -> ALUFunctions.or,
+          InstructionsTypeI.andi -> ALUFunctions.and,
+          InstructionsTypeI.sri -> Mux(io.funct7(5), ALUFunctions.sra, ALUFunctions.srl)
+        ),
+      )
+    }
+    is(InstructionTypes.RM) {
+      io.alu_funct := MuxLookup(
+        io.funct3,
+        ALUFunctions.zero,
+        IndexedSeq(
+          InstructionsTypeR.add_sub -> Mux(io.funct7(5), ALUFunctions.sub, ALUFunctions.add),
+          InstructionsTypeR.sll -> ALUFunctions.sll,
+          InstructionsTypeR.slt -> ALUFunctions.slt,
+          InstructionsTypeR.sltu -> ALUFunctions.sltu,
+          InstructionsTypeR.xor -> ALUFunctions.xor,
+          InstructionsTypeR.or -> ALUFunctions.or,
+          InstructionsTypeR.and -> ALUFunctions.and,
+          InstructionsTypeR.sr -> Mux(io.funct7(5), ALUFunctions.sra, ALUFunctions.srl)
+        ),
+      )
+    }
+    is(InstructionTypes.B) {
+      io.alu_funct := ALUFunctions.add
+    }
+    is(InstructionTypes.L) {
+      io.alu_funct := ALUFunctions.add
+    }
+    is(InstructionTypes.S) {
+      io.alu_funct := ALUFunctions.add
+    }
+    is(Instructions.jal) {
+      io.alu_funct := ALUFunctions.add
+    }
+    is(Instructions.jalr) {
+      io.alu_funct := ALUFunctions.add
+    }
+    is(Instructions.lui) {
+      io.alu_funct := ALUFunctions.add
+    }
+    is(Instructions.auipc) {
+      io.alu_funct := ALUFunctions.add
+    }
+  }
+}

lab4/src/main/scala/riscv/core/fivestage/CLINT.scala

@@ -0,0 +1,183 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+object InterruptStatus {
+  val None = 0x0.U(8.W)
+  val Timer0 = 0x1.U(8.W)
+  val Ret = 0xFF.U(8.W)
+}
+
+object InterruptEntry {
+  val Timer0 = 0x4.U(8.W)
+}
+
+object InterruptState {
+  val Idle = 0x0.U
+  val SyncAssert = 0x1.U
+  val AsyncAssert = 0x2.U
+  val MRET = 0x3.U
+}
+
+object CSRState {
+  val Idle = 0x0.U
+  val MSTATUS = 0x1.U
+  val MEPC = 0x2.U
+  val MRET = 0x3.U
+  val MCAUSE = 0x4.U
+}
+
+// Core Local Interrupt Controller
+class CLINT extends Module {
+  val io = IO(new Bundle {
+    // Interrupt signals from peripherals
+    val interrupt_flag = Input(UInt(Parameters.InterruptFlagWidth))
+
+    // Current instruction from instruction decode
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address_if = Input(UInt(Parameters.AddrWidth))
+
+    val jump_flag = Input(Bool())
+    val jump_address = Input(UInt(Parameters.AddrWidth))
+
+    val csr_mtvec = Input(UInt(Parameters.DataWidth))
+    val csr_mepc = Input(UInt(Parameters.DataWidth))
+    val csr_mstatus = Input(UInt(Parameters.DataWidth))
+
+    // Is global interrupt enabled (from MSTATUS)?
+    val interrupt_enable = Input(Bool())
+
+    val ctrl_stall_flag = Output(Bool())
+
+    val csr_reg_write_enable = Output(Bool())
+    val csr_reg_write_address = Output(UInt(Parameters.CSRRegisterAddrWidth))
+    val csr_reg_write_data = Output(UInt(Parameters.DataWidth))
+
+    val id_interrupt_handler_address = Output(UInt(Parameters.AddrWidth))
+    val id_interrupt_assert = Output(Bool())
+  })
+
+  val interrupt_state = WireInit(0.U)
+  val csr_state = RegInit(CSRState.Idle)
+  val instruction_address = RegInit(UInt(Parameters.AddrWidth), 0.U)
+  val cause = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val interrupt_assert = RegInit(Bool(), false.B)
+  val interrupt_handler_address = RegInit(UInt(Parameters.AddrWidth), 0.U)
+  val csr_reg_write_enable = RegInit(Bool(), false.B)
+  val csr_reg_write_address = RegInit(UInt(Parameters.CSRRegisterAddrWidth), 0.U)
+  val csr_reg_write_data = RegInit(UInt(Parameters.DataWidth), 0.U)
+
+  io.ctrl_stall_flag := interrupt_state =/= InterruptState.Idle || csr_state =/= CSRState.Idle
+
+  // Interrupt FSM
+  when(io.instruction === InstructionsEnv.ecall || io.instruction === InstructionsEnv.ebreak) {
+    interrupt_state := InterruptState.SyncAssert
+  }.elsewhen(io.interrupt_flag =/= InterruptStatus.None && io.interrupt_enable) {
+    interrupt_state := InterruptState.AsyncAssert
+  }.elsewhen(io.instruction === InstructionsRet.mret) {
+    interrupt_state := InterruptState.MRET
+  }.otherwise {
+    interrupt_state := InterruptState.Idle
+  }
+
+  // CSR FSM
+  when(csr_state === CSRState.Idle) {
+    when(interrupt_state === InterruptState.SyncAssert) {
+      // Synchronous Interrupt
+      csr_state := CSRState.MEPC
+      instruction_address := Mux(
+        io.jump_flag,
+        io.jump_address - 4.U,
+        io.instruction_address_if
+      )
+
+      cause := MuxLookup(
+        io.instruction,
+        10.U,
+        IndexedSeq(
+          InstructionsEnv.ecall -> 11.U,
+          InstructionsEnv.ebreak -> 3.U,
+        )
+      )
+    }.elsewhen(interrupt_state === InterruptState.AsyncAssert) {
+      // Asynchronous Interrupt
+      cause := 0x8000000BL.U
+      when(io.interrupt_flag(0)) {
+        cause := 0x80000007L.U
+      }
+      csr_state := CSRState.MEPC
+      instruction_address := Mux(
+        io.jump_flag,
+        io.jump_address,
+        io.instruction_address_if,
+      )
+    }.elsewhen(interrupt_state === InterruptState.MRET) {
+      // Interrupt Return
+      csr_state := CSRState.MRET
+    }
+  }.elsewhen(csr_state === CSRState.MEPC) {
+    csr_state := CSRState.MSTATUS
+  }.elsewhen(csr_state === CSRState.MSTATUS) {
+    csr_state := CSRState.MCAUSE
+  }.elsewhen(csr_state === CSRState.MCAUSE) {
+    csr_state := CSRState.Idle
+  }.elsewhen(csr_state === CSRState.MRET) {
+    csr_state := CSRState.Idle
+  }.otherwise {
+    csr_state := CSRState.Idle
+  }
+
+  csr_reg_write_enable := csr_state =/= CSRState.Idle
+  csr_reg_write_address := Cat(Fill(20, 0.U(1.W)), MuxLookup(
+    csr_state,
+    0.U(Parameters.CSRRegisterAddrWidth),
+    IndexedSeq(
+      CSRState.MEPC -> CSRRegister.MEPC,
+      CSRState.MCAUSE -> CSRRegister.MCAUSE,
+      CSRState.MSTATUS -> CSRRegister.MSTATUS,
+      CSRState.MRET -> CSRRegister.MSTATUS,
+    )
+  ))
+  csr_reg_write_data := MuxLookup(
+    csr_state,
+    0.U(Parameters.DataWidth),
+    IndexedSeq(
+      CSRState.MEPC -> instruction_address,
+      CSRState.MCAUSE -> cause,
+      CSRState.MSTATUS -> Cat(io.csr_mstatus(31, 4), 0.U(1.W), io.csr_mstatus(2, 0)),
+      CSRState.MRET -> Cat(io.csr_mstatus(31, 4), io.csr_mstatus(7), io.csr_mstatus(2, 0)),
+    )
+  )
+  io.csr_reg_write_enable := csr_reg_write_enable
+  io.csr_reg_write_address := csr_reg_write_address
+  io.csr_reg_write_data := csr_reg_write_data
+
+  interrupt_assert := csr_state === CSRState.MCAUSE || csr_state === CSRState.MRET
+  interrupt_handler_address := MuxLookup(
+    csr_state,
+    0.U(Parameters.AddrWidth),
+    IndexedSeq(
+      CSRState.MCAUSE -> io.csr_mtvec,
+      CSRState.MRET -> io.csr_mepc,
+    )
+  )
+
+  io.id_interrupt_assert := interrupt_assert
+  io.id_interrupt_handler_address := interrupt_handler_address
+}

lab4/src/main/scala/riscv/core/fivestage/CPU.scala

@@ -0,0 +1,217 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import bus.{AXI4LiteChannels, AXI4LiteMaster}
+import chisel3._
+import riscv.Parameters
+import riscv.core.CPUBundle
+
+class CPU extends Module {
+  val io = IO(new CPUBundle)
+
+  val ctrl = Module(new Control)
+  val regs = Module(new RegisterFile)
+  val inst_fetch = Module(new InstructionFetch)
+  val if2id = Module(new IF2ID)
+  val id = Module(new InstructionDecode)
+  val id2ex = Module(new ID2EX)
+  val ex = Module(new Execute)
+  val ex2mem = Module(new EX2MEM)
+  val mem = Module(new MemoryAccess)
+  val mem2wb = Module(new MEM2WB)
+  val wb = Module(new WriteBack)
+  val forwarding = Module(new Forwarding)
+  val clint = Module(new CLINT)
+  val csr_regs = Module(new CSR)
+  val axi4_master = Module(new AXI4LiteMaster(Parameters.AddrBits, Parameters.DataBits))
+
+  axi4_master.io.channels <> io.axi4_channels
+  io.debug(0) := ex.io.reg1_data
+  io.debug(1) := ex.io.reg2_data
+  io.debug(2) := ex.io.instruction_address
+  io.debug(3) := ex.io.instruction
+  io.debug(4) := inst_fetch.io.jump_address_id
+  io.debug(5) := inst_fetch.io.jump_flag_id
+  io.bus_busy := axi4_master.io.bundle.busy
+
+  // The MEM module takes precedence over IF (but let the previous fetch finish)
+  val mem_granted = RegInit(false.B)
+  when(mem_granted) {
+    inst_fetch.io.instruction_valid := false.B
+    io.bus_address := mem.io.bus.address
+    axi4_master.io.bundle.read := mem.io.bus.read
+    axi4_master.io.bundle.address := mem.io.bus.address
+    axi4_master.io.bundle.write := mem.io.bus.write
+    axi4_master.io.bundle.write_data := mem.io.bus.write_data
+    axi4_master.io.bundle.write_strobe := mem.io.bus.write_strobe
+    when(!mem.io.bus.request) {
+      mem_granted := false.B
+    }
+  }.otherwise {
+    // Default to fetch instructions from main memory
+    mem_granted := false.B
+    axi4_master.io.bundle.read := !axi4_master.io.bundle.busy && !axi4_master.io.bundle.read_valid && !mem.io.bus.request
+    axi4_master.io.bundle.address := inst_fetch.io.bus_address
+    io.bus_address := inst_fetch.io.bus_address
+    axi4_master.io.bundle.write := false.B
+    axi4_master.io.bundle.write_data := 0.U
+    axi4_master.io.bundle.write_strobe := VecInit(Seq.fill(Parameters.WordSize)(false.B))
+  }
+
+  when(mem.io.bus.request) {
+    when(!axi4_master.io.bundle.busy && !axi4_master.io.bundle.read_valid) {
+      mem_granted := true.B
+    }
+  }
+
+  inst_fetch.io.instruction_valid := io.instruction_valid && axi4_master.io.bundle.read_valid && !mem_granted
+  inst_fetch.io.bus_data := axi4_master.io.bundle.read_data
+
+  mem.io.bus.read_data := axi4_master.io.bundle.read_data
+  mem.io.bus.read_valid := axi4_master.io.bundle.read_valid
+  mem.io.bus.write_valid := axi4_master.io.bundle.write_valid
+  mem.io.bus.busy := axi4_master.io.bundle.busy
+  mem.io.bus.granted := mem_granted
+
+  ctrl.io.jump_flag := id.io.if_jump_flag
+  ctrl.io.stall_flag_if := inst_fetch.io.ctrl_stall_flag
+  ctrl.io.stall_flag_mem := mem.io.ctrl_stall_flag
+  ctrl.io.stall_flag_clint := clint.io.ctrl_stall_flag
+  ctrl.io.stall_flag_bus := io.stall_flag_bus
+  ctrl.io.rs1_id := id.io.regs_reg1_read_address
+  ctrl.io.rs2_id := id.io.regs_reg2_read_address
+  ctrl.io.memory_read_enable_ex := ex2mem.io.memory_read_enable
+  ctrl.io.rd_ex := ex2mem.io.regs_write_address
+
+  regs.io.write_enable := mem2wb.io.output_regs_write_enable
+  regs.io.write_address := mem2wb.io.output_regs_write_address
+  regs.io.write_data := wb.io.regs_write_data
+  regs.io.read_address1 := id.io.regs_reg1_read_address
+  regs.io.read_address2 := id.io.regs_reg2_read_address
+
+  regs.io.debug_read_address := io.debug_read_address
+  io.debug_read_data := regs.io.debug_read_data
+
+  inst_fetch.io.stall_flag_ctrl := ctrl.io.pc_stall
+  inst_fetch.io.jump_flag_id := id.io.if_jump_flag
+  inst_fetch.io.jump_address_id := id.io.if_jump_address
+
+  if2id.io.stall_flag := ctrl.io.if_stall
+  if2id.io.flush_enable := ctrl.io.if_flush
+  if2id.io.instruction := inst_fetch.io.id_instruction
+  if2id.io.instruction_address := inst_fetch.io.id_instruction_address
+  if2id.io.interrupt_flag := io.interrupt_flag
+
+  id.io.reg1_data := regs.io.read_data1
+  id.io.reg2_data := regs.io.read_data2
+  id.io.instruction := if2id.io.output_instruction
+  id.io.instruction_address := if2id.io.output_instruction_address
+  id.io.interrupt_assert := clint.io.id_interrupt_assert
+  id.io.interrupt_handler_address := clint.io.id_interrupt_handler_address
+
+  id2ex.io.stall_flag := ctrl.io.id_stall
+  id2ex.io.flush_enable := ctrl.io.id_flush
+  id2ex.io.instruction := if2id.io.output_instruction
+  id2ex.io.instruction_address := if2id.io.output_instruction_address
+  id2ex.io.regs_write_enable := id.io.ex_reg_write_enable
+  id2ex.io.regs_write_address := id.io.ex_reg_write_address
+  id2ex.io.regs_write_source := id.io.ex_reg_write_source
+  id2ex.io.reg1_data := regs.io.read_data1
+  id2ex.io.reg2_data := regs.io.read_data2
+  id2ex.io.immediate := id.io.ex_immediate
+  id2ex.io.aluop1_source := id.io.ex_aluop1_source
+  id2ex.io.aluop2_source := id.io.ex_aluop2_source
+  id2ex.io.csr_write_enable := id.io.ex_csr_write_enable
+  id2ex.io.csr_address := id.io.ex_csr_address
+  id2ex.io.memory_read_enable := id.io.ex_memory_read_enable
+  id2ex.io.memory_write_enable := id.io.ex_memory_write_enable
+  id2ex.io.csr_read_data := csr_regs.io.id_reg_data
+
+  ex.io.instruction := id2ex.io.output_instruction
+  ex.io.instruction_address := id2ex.io.output_instruction_address
+  ex.io.reg1_data := id2ex.io.output_reg1_data
+  ex.io.reg2_data := id2ex.io.output_reg2_data
+  ex.io.immediate := id2ex.io.output_immediate
+  ex.io.aluop1_source := id2ex.io.output_aluop1_source
+  ex.io.aluop2_source := id2ex.io.output_aluop2_source
+  ex.io.csr_read_data := id2ex.io.output_csr_read_data
+  ex.io.forward_from_mem := mem.io.forward_to_ex
+  ex.io.forward_from_wb := wb.io.regs_write_data
+  ex.io.aluop1_forward := forwarding.io.aluop1_forward_ex
+  ex.io.aluop2_forward := forwarding.io.aluop2_forward_ex
+
+  ex2mem.io.stall_flag := ctrl.io.ex_stall
+  ex2mem.io.flush_enable := false.B
+  ex2mem.io.regs_write_enable := id2ex.io.output_regs_write_enable
+  ex2mem.io.regs_write_source := id2ex.io.output_regs_write_source
+  ex2mem.io.regs_write_address := id2ex.io.output_regs_write_address
+  ex2mem.io.instruction_address := id2ex.io.output_instruction_address
+  ex2mem.io.instruction := id2ex.io.output_instruction
+  ex2mem.io.reg1_data := id2ex.io.output_reg1_data
+  ex2mem.io.reg2_data := id2ex.io.output_reg2_data
+  ex2mem.io.memory_read_enable := id2ex.io.output_memory_read_enable
+  ex2mem.io.memory_write_enable := id2ex.io.output_memory_write_enable
+  ex2mem.io.alu_result := ex.io.mem_alu_result
+  ex2mem.io.csr_read_data := id2ex.io.output_csr_read_data
+
+  mem.io.alu_result := ex2mem.io.output_alu_result
+  mem.io.reg2_data := ex2mem.io.output_reg2_data
+  mem.io.memory_read_enable := ex2mem.io.output_memory_read_enable
+  mem.io.memory_write_enable := ex2mem.io.output_memory_write_enable
+  mem.io.funct3 := ex2mem.io.output_instruction(14, 12)
+  mem.io.regs_write_source := ex2mem.io.output_regs_write_source
+  mem.io.csr_read_data := ex2mem.io.output_csr_read_data
+
+  mem2wb.io.instruction_address := ex2mem.io.output_instruction_address
+  mem2wb.io.alu_result := ex2mem.io.output_alu_result
+  mem2wb.io.regs_write_enable := ex2mem.io.output_regs_write_enable
+  mem2wb.io.regs_write_source := ex2mem.io.output_regs_write_source
+  mem2wb.io.regs_write_address := ex2mem.io.output_regs_write_address
+  mem2wb.io.memory_read_data := mem.io.wb_memory_read_data
+  mem2wb.io.csr_read_data := ex2mem.io.output_csr_read_data
+
+  wb.io.instruction_address := mem2wb.io.output_instruction_address
+  wb.io.alu_result := mem2wb.io.output_alu_result
+  wb.io.memory_read_data := mem2wb.io.output_memory_read_data
+  wb.io.regs_write_source := mem2wb.io.output_regs_write_source
+  wb.io.csr_read_data := mem2wb.io.output_csr_read_data
+
+  forwarding.io.rs1_ex := id2ex.io.output_instruction(19, 15)
+  forwarding.io.rs2_ex := id2ex.io.output_instruction(24, 20)
+  forwarding.io.rd_mem := ex2mem.io.output_regs_write_address
+  forwarding.io.reg_write_enable_mem := ex2mem.io.output_regs_write_enable
+  forwarding.io.rd_wb := mem2wb.io.output_regs_write_address
+  forwarding.io.reg_write_enable_wb := mem2wb.io.output_regs_write_enable
+
+  clint.io.instruction := if2id.io.output_instruction
+  clint.io.instruction_address_if := inst_fetch.io.id_instruction_address
+  clint.io.jump_flag := id.io.if_jump_flag
+  clint.io.jump_address := ex2mem.io.output_alu_result
+  clint.io.csr_mepc := csr_regs.io.clint_csr_mepc
+  clint.io.csr_mtvec := csr_regs.io.clint_csr_mtvec
+  clint.io.csr_mstatus := csr_regs.io.clint_csr_mstatus
+  clint.io.interrupt_enable := csr_regs.io.interrupt_enable
+  clint.io.interrupt_flag := if2id.io.output_interrupt_flag
+
+  csr_regs.io.reg_write_enable_ex := id2ex.io.output_csr_write_enable
+  csr_regs.io.reg_write_address_ex := id2ex.io.output_csr_address
+  csr_regs.io.reg_write_data_ex := ex.io.csr_write_data
+  csr_regs.io.reg_read_address_id := id.io.ex_csr_address
+  csr_regs.io.reg_write_enable_clint := clint.io.csr_reg_write_enable
+  csr_regs.io.reg_write_address_clint := clint.io.csr_reg_write_address
+  csr_regs.io.reg_write_data_clint := clint.io.csr_reg_write_data
+  csr_regs.io.reg_read_address_clint := 0.U
+}

lab4/src/main/scala/riscv/core/fivestage/CSR.scala

@@ -0,0 +1,126 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+
+object CSRRegister {
+  // Refer to Spec. Vol.II Page 8-10
+  val CycleL = 0xc00.U(Parameters.CSRRegisterAddrWidth)
+  val CycleH = 0xc80.U(Parameters.CSRRegisterAddrWidth)
+  val MTVEC = 0x305.U(Parameters.CSRRegisterAddrWidth)
+  val MCAUSE = 0x342.U(Parameters.CSRRegisterAddrWidth)
+  val MEPC = 0x341.U(Parameters.CSRRegisterAddrWidth)
+  val MIE = 0x304.U(Parameters.CSRRegisterAddrWidth)
+  val MSTATUS = 0x300.U(Parameters.CSRRegisterAddrWidth)
+  val MSCRATCH = 0x340.U(Parameters.CSRRegisterAddrWidth)
+}
+
+class CSR extends Module {
+  val io = IO(new Bundle {
+    val reg_write_enable_ex = Input(Bool())
+    val reg_read_address_id = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val reg_write_address_ex = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val reg_write_data_ex = Input(UInt(Parameters.DataWidth))
+
+    val reg_write_enable_clint = Input(Bool())
+    val reg_read_address_clint = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val reg_write_address_clint = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val reg_write_data_clint = Input(UInt(Parameters.DataWidth))
+
+    val interrupt_enable = Output(Bool())
+
+    val id_reg_data = Output(UInt(Parameters.DataWidth))
+
+    val clint_reg_data = Output(UInt(Parameters.DataWidth))
+    val clint_csr_mtvec = Output(UInt(Parameters.DataWidth))
+    val clint_csr_mepc = Output(UInt(Parameters.DataWidth))
+    val clint_csr_mstatus = Output(UInt(Parameters.DataWidth))
+  })
+
+
+  val cycles = RegInit(UInt(64.W), 0.U)
+  val mtvec = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mcause = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mepc = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mie = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mstatus = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mscratch = RegInit(UInt(Parameters.DataWidth), 0.U)
+
+  cycles := cycles + 1.U
+  io.clint_csr_mtvec := mtvec
+  io.clint_csr_mepc := mepc
+  io.clint_csr_mstatus := mstatus
+  io.interrupt_enable := mstatus(3) === 1.U
+
+  val reg_write_address = Wire(UInt(Parameters.CSRRegisterAddrWidth))
+  val reg_write_data = Wire(UInt(Parameters.DataWidth))
+  reg_write_address := 0.U
+  reg_write_data := 0.U
+
+  val reg_read_address = Wire(UInt(Parameters.CSRRegisterAddrWidth))
+  val reg_read_data = Wire(UInt(Parameters.DataWidth))
+  reg_read_address := 0.U
+  reg_read_data := 0.U
+
+  when(io.reg_write_enable_ex) {
+    reg_write_address := io.reg_write_address_ex(11, 0)
+    reg_write_data := io.reg_write_data_ex
+  }.elsewhen(io.reg_write_enable_clint) {
+    reg_write_address := io.reg_write_address_clint(11, 0)
+    reg_write_data := io.reg_write_data_clint
+  }
+
+  when(reg_write_address === CSRRegister.MTVEC) {
+    mtvec := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MCAUSE) {
+    mcause := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MEPC) {
+    mepc := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MIE) {
+    mie := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MSTATUS) {
+    mstatus := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MSCRATCH) {
+    mscratch := reg_write_data
+  }
+
+  val regLUT =
+    IndexedSeq(
+      CSRRegister.CycleL -> cycles(31, 0),
+      CSRRegister.CycleH -> cycles(63, 32),
+      CSRRegister.MTVEC -> mtvec,
+      CSRRegister.MCAUSE -> mcause,
+      CSRRegister.MEPC -> mepc,
+      CSRRegister.MIE -> mie,
+      CSRRegister.MSTATUS -> mstatus,
+      CSRRegister.MSCRATCH -> mscratch,
+    )
+
+  io.id_reg_data := MuxLookup(
+    io.reg_read_address_id,
+    0.U,
+    regLUT,
+  )
+
+  io.clint_reg_data := MuxLookup(
+    io.reg_read_address_clint,
+    0.U,
+    regLUT,
+  )
+}

lab4/src/main/scala/riscv/core/fivestage/Cache.scala

@@ -0,0 +1,23 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+
+class Cache(cacheLineBytes: Int, associativity: Int, cacheLines: Int) extends Module {
+  val io = IO(new Bundle {
+
+  })
+}

lab4/src/main/scala/riscv/core/fivestage/Control.scala

@@ -0,0 +1,48 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import riscv.Parameters
+
+class Control extends Module {
+  val io = IO(new Bundle {
+    val jump_flag = Input(Bool())
+    val stall_flag_if = Input(Bool())
+    val stall_flag_mem = Input(Bool())
+    val stall_flag_clint = Input(Bool())
+    val stall_flag_bus = Input(Bool())
+    val rs1_id = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val rs2_id = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val memory_read_enable_ex = Input(Bool())
+    val rd_ex = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+
+    val if_flush = Output(Bool())
+    val id_flush = Output(Bool())
+    val pc_stall = Output(Bool())
+    val if_stall = Output(Bool())
+    val id_stall = Output(Bool())
+    val ex_stall = Output(Bool())
+  })
+
+  val id_hazard = io.memory_read_enable_ex && (io.rd_ex === io.rs1_id || io.rd_ex === io.rs2_id)
+  io.if_flush := io.jump_flag
+  io.id_flush := id_hazard
+
+  io.pc_stall := io.stall_flag_mem || io.stall_flag_clint || id_hazard || io.stall_flag_bus || io.stall_flag_if
+  io.if_stall := io.stall_flag_mem || io.stall_flag_clint || id_hazard
+  io.id_stall := io.stall_flag_mem || io.stall_flag_clint
+  io.ex_stall := io.stall_flag_mem || io.stall_flag_clint
+}

lab4/src/main/scala/riscv/core/fivestage/EX2MEM.scala

@@ -0,0 +1,115 @@
+// Copyright 2022 Canbin Huang
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import riscv.Parameters
+
+class EX2MEM extends Module {
+  val io = IO(new Bundle() {
+    val stall_flag = Input(Bool())
+    val flush_enable = Input(Bool())
+    val regs_write_enable = Input(Bool())
+    val regs_write_source = Input(UInt(2.W))
+    val regs_write_address = Input(UInt(Parameters.AddrWidth))
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val instruction = Input(UInt(Parameters.DataWidth))
+    val reg1_data = Input(UInt(Parameters.DataWidth))
+    val reg2_data = Input(UInt(Parameters.DataWidth))
+    val memory_read_enable = Input(Bool())
+    val memory_write_enable = Input(Bool())
+    val alu_result = Input(UInt(Parameters.DataWidth))
+    val csr_read_data = Input(UInt(Parameters.DataWidth))
+
+    val output_regs_write_enable = Output(Bool())
+    val output_regs_write_source = Output(UInt(2.W))
+    val output_regs_write_address = Output(UInt(Parameters.AddrWidth))
+    val output_instruction_address = Output(UInt(Parameters.AddrWidth))
+    val output_instruction = Output(UInt(Parameters.DataWidth))
+    val output_reg1_data = Output(UInt(Parameters.DataWidth))
+    val output_reg2_data = Output(UInt(Parameters.DataWidth))
+    val output_memory_read_enable = Output(Bool())
+    val output_memory_write_enable = Output(Bool())
+    val output_alu_result = Output(UInt(Parameters.DataWidth))
+    val output_csr_read_data = Output(UInt(Parameters.DataWidth))
+  })
+  val write_enable = !io.stall_flag
+
+  val regs_write_enable = Module(new PipelineRegister(1))
+  regs_write_enable.io.in := io.regs_write_enable
+  regs_write_enable.io.write_enable := write_enable
+  regs_write_enable.io.flush_enable := io.flush_enable
+  io.output_regs_write_enable := regs_write_enable.io.out
+
+  val regs_write_source = Module(new PipelineRegister(2))
+  regs_write_source.io.in := io.regs_write_source
+  regs_write_source.io.write_enable := write_enable
+  regs_write_source.io.flush_enable := io.flush_enable
+  io.output_regs_write_source := regs_write_source.io.out
+
+  val regs_write_address = Module(new PipelineRegister(Parameters.PhysicalRegisterAddrBits))
+  regs_write_address.io.in := io.regs_write_address
+  regs_write_address.io.write_enable := write_enable
+  regs_write_address.io.flush_enable := io.flush_enable
+  io.output_regs_write_address := regs_write_address.io.out
+
+  val instruction_address = Module(new PipelineRegister(Parameters.AddrBits))
+  instruction_address.io.in := io.instruction_address
+  instruction_address.io.write_enable := write_enable
+  instruction_address.io.flush_enable := io.flush_enable
+  io.output_instruction_address := instruction_address.io.out
+
+  val instruction = Module(new PipelineRegister(Parameters.InstructionBits))
+  instruction.io.in := io.instruction
+  instruction.io.write_enable := write_enable
+  instruction.io.flush_enable := io.flush_enable
+  io.output_instruction := instruction.io.out
+
+  val reg1_data = Module(new PipelineRegister())
+  reg1_data.io.in := io.reg1_data
+  reg1_data.io.write_enable := write_enable
+  reg1_data.io.flush_enable := io.flush_enable
+  io.output_reg1_data := reg1_data.io.out
+
+  val reg2_data = Module(new PipelineRegister())
+  reg2_data.io.in := io.reg2_data
+  reg2_data.io.write_enable := write_enable
+  reg2_data.io.flush_enable := io.flush_enable
+  io.output_reg2_data := reg2_data.io.out
+
+  val alu_result = Module(new PipelineRegister())
+  alu_result.io.in := io.alu_result
+  alu_result.io.write_enable := write_enable
+  alu_result.io.flush_enable := io.flush_enable
+  io.output_alu_result := alu_result.io.out
+
+  val memory_read_enable = Module(new PipelineRegister(1))
+  memory_read_enable.io.in := io.memory_read_enable
+  memory_read_enable.io.write_enable := write_enable
+  memory_read_enable.io.flush_enable := io.flush_enable
+  io.output_memory_read_enable := memory_read_enable.io.out
+
+  val memory_write_enable = Module(new PipelineRegister(1))
+  memory_write_enable.io.in := io.memory_write_enable
+  memory_write_enable.io.write_enable := write_enable
+  memory_write_enable.io.flush_enable := io.flush_enable
+  io.output_memory_write_enable := memory_write_enable.io.out
+
+  val csr_read_data = Module(new PipelineRegister())
+  csr_read_data.io.in := io.csr_read_data
+  csr_read_data.io.write_enable := write_enable
+  csr_read_data.io.flush_enable := io.flush_enable
+  io.output_csr_read_data := csr_read_data.io.out
+}

lab4/src/main/scala/riscv/core/fivestage/Execute.scala

@@ -0,0 +1,91 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.experimental.ChiselEnum
+import chisel3.util._
+import riscv.Parameters
+
+object MemoryAccessStates extends ChiselEnum {
+  val Idle, Read, Write, ReadWrite = Value
+}
+
+class Execute extends Module {
+  val io = IO(new Bundle {
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val reg1_data = Input(UInt(Parameters.DataWidth))
+    val reg2_data = Input(UInt(Parameters.DataWidth))
+    val immediate = Input(UInt(Parameters.DataWidth))
+    val aluop1_source = Input(UInt(1.W))
+    val aluop2_source = Input(UInt(1.W))
+    val csr_read_data = Input(UInt(Parameters.DataWidth))
+    val forward_from_mem = Input(UInt(Parameters.DataWidth))
+    val forward_from_wb = Input(UInt(Parameters.DataWidth))
+    val aluop1_forward = Input(UInt(2.W))
+    val aluop2_forward = Input(UInt(2.W))
+
+    val mem_alu_result = Output(UInt(Parameters.DataWidth))
+    val csr_write_data = Output(UInt(Parameters.DataWidth))
+  })
+
+  val opcode = io.instruction(6, 0)
+  val funct3 = io.instruction(14, 12)
+  val funct7 = io.instruction(31, 25)
+  val rd = io.instruction(11, 7)
+  val uimm = io.instruction(19, 15)
+
+  val alu = Module(new ALU)
+  val alu_ctrl = Module(new ALUControl)
+
+  alu_ctrl.io.opcode := opcode
+  alu_ctrl.io.funct3 := funct3
+  alu_ctrl.io.funct7 := funct7
+  alu.io.func := alu_ctrl.io.alu_funct
+  alu.io.op1 := Mux(
+    io.aluop1_source === ALUOp1Source.InstructionAddress,
+    io.instruction_address,
+    MuxLookup(
+      io.aluop1_forward,
+      io.reg1_data,
+      IndexedSeq(
+        ForwardingType.ForwardFromMEM -> io.forward_from_mem,
+        ForwardingType.ForwardFromWB -> io.forward_from_wb
+      )
+    )
+  )
+  alu.io.op2 := Mux(
+    io.aluop2_source === ALUOp2Source.Immediate,
+    io.immediate,
+    MuxLookup(
+      io.aluop2_forward,
+      io.reg2_data,
+      IndexedSeq(
+        ForwardingType.ForwardFromMEM -> io.forward_from_mem,
+        ForwardingType.ForwardFromWB -> io.forward_from_wb
+      )
+    )
+  )
+  io.mem_alu_result := alu.io.result
+  io.csr_write_data := MuxLookup(funct3, 0.U, IndexedSeq(
+    InstructionsTypeCSR.csrrw -> io.reg1_data,
+    InstructionsTypeCSR.csrrc -> io.csr_read_data.&((~io.reg1_data).asUInt),
+    InstructionsTypeCSR.csrrs -> io.csr_read_data.|(io.reg1_data),
+    InstructionsTypeCSR.csrrwi -> Cat(0.U(27.W), uimm),
+    InstructionsTypeCSR.csrrci -> io.csr_read_data.&((~Cat(0.U(27.W), uimm)).asUInt),
+    InstructionsTypeCSR.csrrsi -> io.csr_read_data.|(Cat(0.U(27.W), uimm)),
+  ))
+}

lab4/src/main/scala/riscv/core/fivestage/Forwarding.scala

@@ -0,0 +1,53 @@
+// Copyright 2022 Canbin Huang
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import riscv.Parameters
+
+object ForwardingType {
+  val NoForward = 0.U(2.W)
+  val ForwardFromMEM = 1.U(2.W)
+  val ForwardFromWB = 2.U(2.W)
+}
+
+class Forwarding extends Module {
+  val io = IO(new Bundle() {
+    val rs1_ex = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val rs2_ex = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val rd_mem = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val reg_write_enable_mem = Input(Bool())
+    val rd_wb = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val reg_write_enable_wb = Input(Bool())
+
+    val aluop1_forward_ex = Output(UInt(2.W))
+    val aluop2_forward_ex = Output(UInt(2.W))
+  })
+  when(io.reg_write_enable_mem && io.rd_mem =/= 0.U && io.rd_mem === io.rs1_ex) {
+    io.aluop1_forward_ex := ForwardingType.ForwardFromMEM
+  }.elsewhen(io.reg_write_enable_wb && io.rd_wb =/= 0.U && io.rd_wb === io.rs1_ex) {
+    io.aluop1_forward_ex := ForwardingType.ForwardFromWB
+  }.otherwise {
+    io.aluop1_forward_ex := ForwardingType.NoForward
+  }
+
+  when(io.reg_write_enable_mem && io.rd_mem =/= 0.U && io.rd_mem === io.rs2_ex) {
+    io.aluop2_forward_ex := ForwardingType.ForwardFromMEM
+  }.elsewhen(io.reg_write_enable_wb && io.rd_wb =/= 0.U && io.rd_wb === io.rs2_ex) {
+    io.aluop2_forward_ex := ForwardingType.ForwardFromWB
+  }.otherwise {
+    io.aluop2_forward_ex := ForwardingType.NoForward
+  }
+}

lab4/src/main/scala/riscv/core/fivestage/ID2EX.scala

@@ -0,0 +1,147 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import riscv.Parameters
+
+class ID2EX extends Module {
+  val io = IO(new Bundle {
+    val stall_flag = Input(Bool())
+    val flush_enable = Input(Bool())
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val regs_write_enable = Input(Bool())
+    val regs_write_address = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val regs_write_source = Input(UInt(2.W))
+    val reg1_data = Input(UInt(Parameters.DataWidth))
+    val reg2_data = Input(UInt(Parameters.DataWidth))
+    val immediate = Input(UInt(Parameters.DataWidth))
+    val aluop1_source = Input(UInt(1.W))
+    val aluop2_source = Input(UInt(1.W))
+    val csr_write_enable = Input(Bool())
+    val csr_address = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val memory_read_enable = Input(Bool())
+    val memory_write_enable = Input(Bool())
+    val csr_read_data = Input(UInt(Parameters.DataWidth))
+
+    val output_instruction = Output(UInt(Parameters.DataWidth))
+    val output_instruction_address = Output(UInt(Parameters.AddrWidth))
+    val output_regs_write_enable = Output(Bool())
+    val output_regs_write_address = Output(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val output_regs_write_source = Output(UInt(2.W))
+    val output_reg1_data = Output(UInt(Parameters.DataWidth))
+    val output_reg2_data = Output(UInt(Parameters.DataWidth))
+    val output_immediate = Output(UInt(Parameters.DataWidth))
+    val output_aluop1_source = Output(UInt(1.W))
+    val output_aluop2_source = Output(UInt(1.W))
+    val output_csr_write_enable = Output(Bool())
+    val output_csr_address = Output(UInt(Parameters.CSRRegisterAddrWidth))
+    val output_memory_read_enable = Output(Bool())
+    val output_memory_write_enable = Output(Bool())
+    val output_csr_read_data = Output(UInt(Parameters.DataWidth))
+  })
+  val write_enable = !io.stall_flag
+
+  val instruction = Module(new PipelineRegister(defaultValue = InstructionsNop.nop))
+  instruction.io.in := io.instruction
+  instruction.io.write_enable := write_enable
+  instruction.io.flush_enable := io.flush_enable
+  io.output_instruction := instruction.io.out
+
+  val instruction_address = Module(new PipelineRegister(defaultValue = ProgramCounter.EntryAddress))
+  instruction_address.io.in := io.instruction_address
+  instruction_address.io.write_enable := write_enable
+  instruction_address.io.flush_enable := io.flush_enable
+  io.output_instruction_address := instruction_address.io.out
+
+  val regs_write_enable = Module(new PipelineRegister(1))
+  regs_write_enable.io.in := io.regs_write_enable
+  regs_write_enable.io.write_enable := write_enable
+  regs_write_enable.io.flush_enable := io.flush_enable
+  io.output_regs_write_enable := regs_write_enable.io.out
+
+  val regs_write_address = Module(new PipelineRegister(Parameters.PhysicalRegisterAddrBits))
+  regs_write_address.io.in := io.regs_write_address
+  regs_write_address.io.write_enable := write_enable
+  regs_write_address.io.flush_enable := io.flush_enable
+  io.output_regs_write_address := regs_write_address.io.out
+
+  val regs_write_source = Module(new PipelineRegister(2))
+  regs_write_source.io.in := io.regs_write_source
+  regs_write_source.io.write_enable := write_enable
+  regs_write_source.io.flush_enable := io.flush_enable
+  io.output_regs_write_source := regs_write_source.io.out
+
+  val reg1_data = Module(new PipelineRegister())
+  reg1_data.io.in := io.reg1_data
+  reg1_data.io.write_enable := write_enable
+  reg1_data.io.flush_enable := io.flush_enable
+  io.output_reg1_data := reg1_data.io.out
+
+  val reg2_data = Module(new PipelineRegister())
+  reg2_data.io.in := io.reg2_data
+  reg2_data.io.write_enable := write_enable
+  reg2_data.io.flush_enable := io.flush_enable
+  io.output_reg2_data := reg2_data.io.out
+
+  val immediate = Module(new PipelineRegister())
+  immediate.io.in := io.immediate
+  immediate.io.write_enable := write_enable
+  immediate.io.flush_enable := io.flush_enable
+  io.output_immediate := immediate.io.out
+
+  val aluop1_source = Module(new PipelineRegister(1))
+  aluop1_source.io.in := io.aluop1_source
+  aluop1_source.io.write_enable := write_enable
+  aluop1_source.io.flush_enable := io.flush_enable
+  io.output_aluop1_source := aluop1_source.io.out
+
+  val aluop2_source = Module(new PipelineRegister(1))
+  aluop2_source.io.in := io.aluop2_source
+  aluop2_source.io.write_enable := write_enable
+  aluop2_source.io.flush_enable := io.flush_enable
+  io.output_aluop2_source := aluop2_source.io.out
+
+  val csr_write_enable = Module(new PipelineRegister(1))
+  csr_write_enable.io.in := io.csr_write_enable
+  csr_write_enable.io.write_enable := write_enable
+  csr_write_enable.io.flush_enable := io.flush_enable
+  io.output_csr_write_enable := csr_write_enable.io.out
+
+  val csr_address = Module(new PipelineRegister(Parameters.CSRRegisterAddrBits))
+  csr_address.io.in := io.csr_address
+  csr_address.io.write_enable := write_enable
+  csr_address.io.flush_enable := io.flush_enable
+  io.output_csr_address := csr_address.io.out
+
+  val memory_read_enable = Module(new PipelineRegister(1))
+  memory_read_enable.io.in := io.memory_read_enable
+  memory_read_enable.io.write_enable := write_enable
+  memory_read_enable.io.flush_enable := io.flush_enable
+  io.output_memory_read_enable := memory_read_enable.io.out
+
+  val memory_write_enable = Module(new PipelineRegister(1))
+  memory_write_enable.io.in := io.memory_write_enable
+  memory_write_enable.io.write_enable := write_enable
+  memory_write_enable.io.flush_enable := io.flush_enable
+  io.output_memory_write_enable := memory_write_enable.io.out
+
+  val csr_read_data = Module(new PipelineRegister())
+  csr_read_data.io.in := io.csr_read_data
+  csr_read_data.io.write_enable := write_enable
+  csr_read_data.io.flush_enable := io.flush_enable
+  io.output_csr_read_data := csr_read_data.io.out
+}

lab4/src/main/scala/riscv/core/fivestage/IF2ID.scala

@@ -0,0 +1,52 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import riscv.Parameters
+
+class IF2ID extends Module {
+  val io = IO(new Bundle {
+    val stall_flag = Input(Bool())
+    val flush_enable = Input(Bool())
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val interrupt_flag = Input(UInt(Parameters.InterruptFlagWidth))
+
+    val output_instruction = Output(UInt(Parameters.DataWidth))
+    val output_instruction_address = Output(UInt(Parameters.AddrWidth))
+    val output_interrupt_flag = Output(UInt(Parameters.InterruptFlagWidth))
+  })
+
+  val write_enable = !io.stall_flag
+
+  val instruction = Module(new PipelineRegister(defaultValue = InstructionsNop.nop))
+  instruction.io.in := io.instruction
+  instruction.io.write_enable := write_enable
+  instruction.io.flush_enable := io.flush_enable
+  io.output_instruction := instruction.io.out
+
+  val instruction_address = Module(new PipelineRegister(defaultValue = ProgramCounter.EntryAddress))
+  instruction_address.io.in := io.instruction_address
+  instruction_address.io.write_enable := write_enable
+  instruction_address.io.flush_enable := io.flush_enable
+  io.output_instruction_address := instruction_address.io.out
+
+  val interrupt_flag = Module(new PipelineRegister(Parameters.InterruptFlagBits))
+  interrupt_flag.io.in := io.interrupt_flag
+  interrupt_flag.io.write_enable := write_enable
+  interrupt_flag.io.flush_enable := io.flush_enable
+  io.output_interrupt_flag := interrupt_flag.io.out
+}

lab4/src/main/scala/riscv/core/fivestage/InstructionDecode.scala

@@ -0,0 +1,238 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+object InstructionTypes {
+  val L = "b0000011".U
+  val I = "b0010011".U
+  val S = "b0100011".U
+  val RM = "b0110011".U
+  val B = "b1100011".U
+}
+
+object Instructions {
+  val lui = "b0110111".U
+  val nop = "b0000001".U
+  val jal = "b1101111".U
+  val jalr = "b1100111".U
+  val auipc = "b0010111".U
+  val csr = "b1110011".U
+  val fence = "b0001111".U
+}
+
+object InstructionsTypeL {
+  val lb = "b000".U
+  val lh = "b001".U
+  val lw = "b010".U
+  val lbu = "b100".U
+  val lhu = "b101".U
+}
+
+object InstructionsTypeI {
+  val addi = 0.U
+  val slli = 1.U
+  val slti = 2.U
+  val sltiu = 3.U
+  val xori = 4.U
+  val sri = 5.U
+  val ori = 6.U
+  val andi = 7.U
+}
+
+object InstructionsTypeS {
+  val sb = "b000".U
+  val sh = "b001".U
+  val sw = "b010".U
+}
+
+object InstructionsTypeR {
+  val add_sub = 0.U
+  val sll = 1.U
+  val slt = 2.U
+  val sltu = 3.U
+  val xor = 4.U
+  val sr = 5.U
+  val or = 6.U
+  val and = 7.U
+}
+
+object InstructionsTypeM {
+  val mul = 0.U
+  val mulh = 1.U
+  val mulhsu = 2.U
+  val mulhum = 3.U
+  val div = 4.U
+  val divu = 5.U
+  val rem = 6.U
+  val remu = 7.U
+}
+
+object InstructionsTypeB {
+  val beq = "b000".U
+  val bne = "b001".U
+  val blt = "b100".U
+  val bge = "b101".U
+  val bltu = "b110".U
+  val bgeu = "b111".U
+}
+
+object InstructionsTypeCSR {
+  val csrrw = "b001".U
+  val csrrs = "b010".U
+  val csrrc = "b011".U
+  val csrrwi = "b101".U
+  val csrrsi = "b110".U
+  val csrrci = "b111".U
+}
+
+object InstructionsNop {
+  val nop = 0x00000013L.U(Parameters.DataWidth)
+}
+
+object InstructionsRet {
+  val mret = 0x30200073L.U(Parameters.DataWidth)
+  val ret = 0x00008067L.U(Parameters.DataWidth)
+}
+
+object InstructionsEnv {
+  val ecall = 0x00000073L.U(Parameters.DataWidth)
+  val ebreak = 0x00100073L.U(Parameters.DataWidth)
+}
+
+object ALUOp1Source {
+  val Register = 0.U(1.W)
+  val InstructionAddress = 1.U(1.W)
+}
+
+object ALUOp2Source {
+  val Register = 0.U(1.W)
+  val Immediate = 1.U(1.W)
+}
+
+object RegWriteSource {
+  val ALUResult = 0.U(2.W)
+  val Memory = 1.U(2.W)
+  val CSR = 2.U(2.W)
+  val NextInstructionAddress = 3.U(2.W)
+}
+
+class InstructionDecode extends Module {
+  val io = IO(new Bundle {
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val reg1_data = Input(UInt(Parameters.DataWidth))
+    val reg2_data = Input(UInt(Parameters.DataWidth))
+    val interrupt_assert = Input(Bool())
+    val interrupt_handler_address = Input(UInt(Parameters.AddrWidth))
+
+    val regs_reg1_read_address = Output(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val regs_reg2_read_address = Output(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val ex_reg1_data = Output(UInt(Parameters.DataWidth))
+    val ex_reg2_data = Output(UInt(Parameters.DataWidth))
+    val ex_immediate = Output(UInt(Parameters.DataWidth))
+    val ex_aluop1_source = Output(UInt(1.W))
+    val ex_aluop2_source = Output(UInt(1.W))
+    val ex_memory_read_enable = Output(Bool())
+    val ex_memory_write_enable = Output(Bool())
+    val ex_reg_write_source = Output(UInt(2.W))
+    val ex_reg_write_enable = Output(Bool())
+    val ex_reg_write_address = Output(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val ex_csr_address = Output(UInt(Parameters.CSRRegisterAddrWidth))
+    val ex_csr_write_enable = Output(Bool())
+    val if_jump_flag = Output(Bool())
+    val if_jump_address = Output(UInt(Parameters.AddrWidth))
+  })
+  val opcode = io.instruction(6, 0)
+  val funct3 = io.instruction(14, 12)
+  val funct7 = io.instruction(31, 25)
+  val rd = io.instruction(11, 7)
+  val rs1 = io.instruction(19, 15)
+  val rs2 = io.instruction(24, 20)
+
+  io.regs_reg1_read_address := Mux(opcode === Instructions.lui, 0.U(Parameters.PhysicalRegisterAddrWidth), rs1)
+  io.regs_reg2_read_address := rs2
+  io.ex_reg1_data := io.reg1_data
+  io.ex_reg2_data := io.reg2_data
+  val immediate = MuxLookup(
+    opcode,
+    Cat(Fill(20, io.instruction(31)), io.instruction(31, 20)),
+    IndexedSeq(
+      InstructionTypes.I -> Cat(Fill(21, io.instruction(31)), io.instruction(30, 20)),
+      InstructionTypes.L -> Cat(Fill(21, io.instruction(31)), io.instruction(30, 20)),
+      Instructions.jalr -> Cat(Fill(21, io.instruction(31)), io.instruction(30, 20)),
+      InstructionTypes.S -> Cat(Fill(21, io.instruction(31)), io.instruction(30, 25), io.instruction(11, 7)),
+      InstructionTypes.B -> Cat(Fill(20, io.instruction(31)), io.instruction(7), io.instruction(30, 25), io.instruction(11, 8), 0.U(1.W)),
+      Instructions.lui -> Cat(io.instruction(31, 12), 0.U(12.W)),
+      Instructions.auipc -> Cat(io.instruction(31, 12), 0.U(12.W)),
+      Instructions.jal -> Cat(Fill(12, io.instruction(31)), io.instruction(19, 12), io.instruction(20), io.instruction(30, 21), 0.U(1.W))
+    )
+  )
+  io.ex_immediate := immediate
+  io.ex_aluop1_source := Mux(
+    opcode === Instructions.auipc || opcode === InstructionTypes.B || opcode === Instructions.jal,
+    ALUOp1Source.InstructionAddress,
+    ALUOp1Source.Register
+  )
+  io.ex_aluop2_source := Mux(
+    opcode === InstructionTypes.RM,
+    ALUOp2Source.Register,
+    ALUOp2Source.Immediate
+  )
+  io.ex_memory_read_enable := opcode === InstructionTypes.L
+  io.ex_memory_write_enable := opcode === InstructionTypes.S
+  io.ex_reg_write_source := MuxLookup(
+    opcode,
+    RegWriteSource.ALUResult,
+    IndexedSeq(
+      InstructionTypes.L -> RegWriteSource.Memory,
+      Instructions.csr -> RegWriteSource.CSR,
+      Instructions.jal -> RegWriteSource.NextInstructionAddress,
+      Instructions.jalr -> RegWriteSource.NextInstructionAddress
+    )
+  )
+  io.ex_reg_write_enable := (opcode === InstructionTypes.RM) || (opcode === InstructionTypes.I) ||
+    (opcode === InstructionTypes.L) || (opcode === Instructions.auipc) || (opcode === Instructions.lui) ||
+    (opcode === Instructions.jal) || (opcode === Instructions.jalr) || (opcode === Instructions.csr)
+  io.ex_reg_write_address := io.instruction(11, 7)
+  io.ex_csr_address := io.instruction(31, 20)
+  io.ex_csr_write_enable := (opcode === Instructions.csr) && (
+    funct3 === InstructionsTypeCSR.csrrw || funct3 === InstructionsTypeCSR.csrrwi ||
+      funct3 === InstructionsTypeCSR.csrrs || funct3 === InstructionsTypeCSR.csrrsi ||
+      funct3 === InstructionsTypeCSR.csrrc || funct3 === InstructionsTypeCSR.csrrci
+    )
+  io.if_jump_flag := io.interrupt_assert ||
+    (opcode === Instructions.jal) ||
+    (opcode === Instructions.jalr) ||
+    (opcode === InstructionTypes.B) && MuxLookup(
+      funct3,
+      false.B,
+      IndexedSeq(
+        InstructionsTypeB.beq -> (io.reg1_data === io.reg2_data),
+        InstructionsTypeB.bne -> (io.reg1_data =/= io.reg2_data),
+        InstructionsTypeB.blt -> (io.reg1_data.asSInt < io.reg2_data.asSInt),
+        InstructionsTypeB.bge -> (io.reg1_data.asSInt >= io.reg2_data.asSInt),
+        InstructionsTypeB.bltu -> (io.reg1_data.asUInt < io.reg2_data.asUInt),
+        InstructionsTypeB.bgeu -> (io.reg1_data.asUInt >= io.reg2_data.asUInt)
+      )
+    )
+  io.if_jump_address := Mux(io.interrupt_assert,
+    io.interrupt_handler_address,
+    io.ex_immediate + Mux(opcode === Instructions.jalr, io.reg1_data, io.instruction_address)
+  )
+}

lab4/src/main/scala/riscv/core/fivestage/InstructionFetch.scala

@@ -0,0 +1,68 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.util.MuxCase
+import riscv.Parameters
+
+object ProgramCounter {
+  val EntryAddress = Parameters.EntryAddress
+}
+
+class InstructionFetch extends Module {
+  val io = IO(new Bundle {
+    val stall_flag_ctrl = Input(Bool())
+    val jump_flag_id = Input(Bool())
+    val jump_address_id = Input(UInt(Parameters.AddrWidth))
+    val instruction_valid = Input(Bool())
+
+    val bus_request = Output(Bool())
+    val bus_address = Output(UInt(Parameters.AddrWidth))
+    val bus_data = Input(UInt(Parameters.InstructionWidth))
+    val bus_read = Output(Bool())
+
+    val ctrl_stall_flag = Output(Bool())
+    val id_instruction_address = Output(UInt(Parameters.AddrWidth))
+    val id_instruction = Output(UInt(Parameters.InstructionWidth))
+  })
+  val pending_jump = RegInit(false.B)
+  val pc = RegInit(ProgramCounter.EntryAddress)
+  io.bus_read := true.B
+  io.bus_request := true.B
+
+  pc := MuxCase(
+    pc + 4.U,
+    IndexedSeq(
+      io.jump_flag_id -> io.jump_address_id,
+      io.stall_flag_ctrl -> pc
+    )
+  )
+  when(!io.instruction_valid) {
+    when(io.jump_flag_id) {
+      pending_jump := true.B
+    }
+  }
+  when(io.instruction_valid) {
+    when(pending_jump) {
+      pending_jump := false.B
+    }
+  }
+  io.id_instruction := Mux(io.instruction_valid && !io.jump_flag_id && !pending_jump, io.bus_data,
+    InstructionsNop.nop)
+  io.ctrl_stall_flag := !io.instruction_valid || pending_jump
+  io.id_instruction_address := pc
+  io.bus_address := pc
+}

lab4/src/main/scala/riscv/core/fivestage/MEM2WB.scala

@@ -0,0 +1,82 @@
+// Copyright 2022 Canbin Huang
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import riscv.Parameters
+
+class MEM2WB extends Module {
+  val io = IO(new Bundle() {
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val alu_result = Input(UInt(Parameters.DataWidth))
+    val regs_write_enable = Input(Bool())
+    val regs_write_source = Input(UInt(2.W))
+    val regs_write_address = Input(UInt(Parameters.AddrWidth))
+    val memory_read_data = Input(UInt(Parameters.DataWidth))
+    val csr_read_data = Input(UInt(Parameters.DataWidth))
+
+    val output_instruction_address = Output(UInt(Parameters.AddrWidth))
+    val output_alu_result = Output(UInt(Parameters.DataWidth))
+    val output_regs_write_enable = Output(Bool())
+    val output_regs_write_source = Output(UInt(2.W))
+    val output_regs_write_address = Output(UInt(Parameters.AddrWidth))
+    val output_memory_read_data = Output(UInt(Parameters.DataWidth))
+    val output_csr_read_data = Output(UInt(Parameters.DataWidth))
+  })
+  val flush_enable = false.B
+  val write_enable = true.B
+
+  val alu_result = Module(new PipelineRegister())
+  alu_result.io.in := io.alu_result
+  alu_result.io.write_enable := write_enable
+  alu_result.io.flush_enable := flush_enable
+  io.output_alu_result := alu_result.io.out
+
+  val memory_read_data = Module(new PipelineRegister())
+  memory_read_data.io.in := io.memory_read_data
+  memory_read_data.io.write_enable := write_enable
+  memory_read_data.io.flush_enable := flush_enable
+  io.output_memory_read_data := memory_read_data.io.out
+
+  val regs_write_enable = Module(new PipelineRegister(1))
+  regs_write_enable.io.in := io.regs_write_enable
+  regs_write_enable.io.write_enable := write_enable
+  regs_write_enable.io.flush_enable := flush_enable
+  io.output_regs_write_enable := regs_write_enable.io.out
+
+  val regs_write_source = Module(new PipelineRegister(2))
+  regs_write_source.io.in := io.regs_write_source
+  regs_write_source.io.write_enable := write_enable
+  regs_write_source.io.flush_enable := flush_enable
+  io.output_regs_write_source := regs_write_source.io.out
+
+  val regs_write_address = Module(new PipelineRegister(Parameters.PhysicalRegisterAddrBits))
+  regs_write_address.io.in := io.regs_write_address
+  regs_write_address.io.write_enable := write_enable
+  regs_write_address.io.flush_enable := flush_enable
+  io.output_regs_write_address := regs_write_address.io.out
+
+  val instruction_address = Module(new PipelineRegister(Parameters.InstructionBits))
+  instruction_address.io.in := io.instruction_address
+  instruction_address.io.write_enable := write_enable
+  instruction_address.io.flush_enable := flush_enable
+  io.output_instruction_address := instruction_address.io.out
+
+  val csr_read_data = Module(new PipelineRegister())
+  csr_read_data.io.in := io.csr_read_data
+  csr_read_data.io.write_enable := write_enable
+  csr_read_data.io.flush_enable := flush_enable
+  io.output_csr_read_data := csr_read_data.io.out
+}

lab4/src/main/scala/riscv/core/fivestage/MemoryAccess.scala

@@ -0,0 +1,151 @@
+// Copyright 2022 Canbin Huang
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+import riscv.core.BusBundle
+
+class MemoryAccess extends Module {
+  val io = IO(new Bundle() {
+    val alu_result = Input(UInt(Parameters.DataWidth))
+    val reg2_data = Input(UInt(Parameters.DataWidth))
+    val memory_read_enable = Input(Bool())
+    val memory_write_enable = Input(Bool())
+    val funct3 = Input(UInt(3.W))
+    val regs_write_source = Input(UInt(2.W))
+    val csr_read_data = Input(UInt(Parameters.DataWidth))
+
+    val wb_memory_read_data = Output(UInt(Parameters.DataWidth))
+    val ctrl_stall_flag = Output(Bool())
+    val forward_to_ex = Output(UInt(Parameters.DataWidth))
+
+    val bus = new BusBundle
+  })
+  val mem_address_index = io.alu_result(log2Up(Parameters.WordSize) - 1, 0).asUInt
+  val mem_access_state = RegInit(MemoryAccessStates.Idle)
+
+  def on_bus_transaction_finished() = {
+    mem_access_state := MemoryAccessStates.Idle
+    io.ctrl_stall_flag := false.B
+  }
+
+  io.bus.request := false.B
+  io.bus.read := false.B
+  io.bus.address := io.alu_result(Parameters.AddrBits - 1, log2Up(Parameters.WordSize)) ## 0.U(log2Up(Parameters.WordSize).W)
+  io.bus.write_data := 0.U
+  io.bus.write_strobe := VecInit(Seq.fill(Parameters.WordSize)(false.B))
+  io.bus.write := false.B
+  io.wb_memory_read_data := 0.U
+  io.ctrl_stall_flag := false.B
+
+  when(io.memory_read_enable) {
+    when(mem_access_state === MemoryAccessStates.Idle) {
+      // Start the read transaction when the bus is available
+      io.ctrl_stall_flag := true.B
+      io.bus.read := true.B
+      io.bus.request := true.B
+      when(io.bus.granted) {
+        mem_access_state := MemoryAccessStates.Read
+      }
+    }.elsewhen(mem_access_state === MemoryAccessStates.Read) {
+      io.bus.request := true.B
+      io.bus.read := false.B
+      io.ctrl_stall_flag := true.B
+      when(io.bus.read_valid) {
+        val data = io.bus.read_data
+        io.wb_memory_read_data := MuxLookup(
+          io.funct3,
+          0.U,
+          IndexedSeq(
+            InstructionsTypeL.lb -> MuxLookup(
+              mem_address_index,
+              Cat(Fill(24, data(31)), data(31, 24)),
+              IndexedSeq(
+                0.U -> Cat(Fill(24, data(7)), data(7, 0)),
+                1.U -> Cat(Fill(24, data(15)), data(15, 8)),
+                2.U -> Cat(Fill(24, data(23)), data(23, 16))
+              )
+            ),
+            InstructionsTypeL.lbu -> MuxLookup(
+              mem_address_index,
+              Cat(Fill(24, 0.U), data(31, 24)),
+              IndexedSeq(
+                0.U -> Cat(Fill(24, 0.U), data(7, 0)),
+                1.U -> Cat(Fill(24, 0.U), data(15, 8)),
+                2.U -> Cat(Fill(24, 0.U), data(23, 16))
+              )
+            ),
+            InstructionsTypeL.lh -> Mux(
+              mem_address_index === 0.U,
+              Cat(Fill(16, data(15)), data(15, 0)),
+              Cat(Fill(16, data(31)), data(31, 16))
+            ),
+            InstructionsTypeL.lhu -> Mux(
+              mem_address_index === 0.U,
+              Cat(Fill(16, 0.U), data(15, 0)),
+              Cat(Fill(16, 0.U), data(31, 16))
+            ),
+            InstructionsTypeL.lw -> data
+          )
+        )
+        on_bus_transaction_finished()
+      }
+    }
+  }.elsewhen(io.memory_write_enable) {
+    when(mem_access_state === MemoryAccessStates.Idle) {
+      // Start the write transaction when there the bus is available
+      io.ctrl_stall_flag := true.B
+      io.bus.write_data := io.reg2_data
+      io.bus.write := true.B
+      io.bus.write_strobe := VecInit(Seq.fill(Parameters.WordSize)(false.B))
+      when(io.funct3 === InstructionsTypeS.sb) {
+        io.bus.write_strobe(mem_address_index) := true.B
+        io.bus.write_data := io.reg2_data(Parameters.ByteBits, 0) << (mem_address_index << log2Up(Parameters.ByteBits).U)
+      }.elsewhen(io.funct3 === InstructionsTypeS.sh) {
+        when(mem_address_index === 0.U) {
+          for (i <- 0 until Parameters.WordSize / 2) {
+            io.bus.write_strobe(i) := true.B
+          }
+          io.bus.write_data := io.reg2_data(Parameters.WordSize / 2 * Parameters.ByteBits, 0)
+        }.otherwise {
+          for (i <- Parameters.WordSize / 2 until Parameters.WordSize) {
+            io.bus.write_strobe(i) := true.B
+          }
+          io.bus.write_data := io.reg2_data(Parameters.WordSize / 2 * Parameters.ByteBits, 0) << (Parameters
+            .WordSize / 2 * Parameters.ByteBits)
+        }
+      }.elsewhen(io.funct3 === InstructionsTypeS.sw) {
+        for (i <- 0 until Parameters.WordSize) {
+          io.bus.write_strobe(i) := true.B
+        }
+      }
+      io.bus.request := true.B
+      when(io.bus.granted) {
+        mem_access_state := MemoryAccessStates.Write
+      }
+    }.elsewhen(mem_access_state === MemoryAccessStates.Write) {
+      io.bus.request := true.B
+      io.ctrl_stall_flag := true.B
+      io.bus.write := false.B
+      when(io.bus.write_valid) {
+        on_bus_transaction_finished()
+      }
+    }
+  }
+
+  io.forward_to_ex := Mux(io.regs_write_source === RegWriteSource.CSR, io.csr_read_data, io.alu_result)
+}

lab4/src/main/scala/riscv/core/fivestage/PipelineRegister.scala

@@ -0,0 +1,35 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import riscv.Parameters
+
+class PipelineRegister(width: Int = Parameters.DataBits, defaultValue: UInt = 0.U) extends Module {
+  val io = IO(new Bundle {
+    val write_enable = Input(Bool())
+    val flush_enable = Input(Bool())
+    val in = Input(UInt(width.W))
+    val out = Output(UInt(width.W))
+  })
+
+  val reg = RegInit(UInt(width.W), defaultValue)
+  when(io.write_enable) {
+    reg := io.in
+  }.elsewhen(io.flush_enable) {
+    reg := defaultValue
+  }
+  io.out := reg
+}

lab4/src/main/scala/riscv/core/fivestage/RegisterFile.scala

@@ -0,0 +1,78 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+object Registers extends Enumeration {
+  type Register = Value
+  val zero,
+  ra, sp, gp, tp,
+  t0, t1, t2, fp,
+  s1,
+  a0, a1, a2, a3, a4, a5, a6, a7,
+  s2, s3, s4, s5, s6, s7, s8, s9, s10, s11,
+  t3, t4, t5, t6 = Value
+}
+
+class RegisterFile extends Module {
+  val io = IO(new Bundle {
+    val write_enable = Input(Bool())
+    val write_address = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val write_data = Input(UInt(Parameters.DataWidth))
+
+    val read_address1 = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val read_address2 = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val read_data1 = Output(UInt(Parameters.DataWidth))
+    val read_data2 = Output(UInt(Parameters.DataWidth))
+
+    val debug_read_address = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val debug_read_data = Output(UInt(Parameters.DataWidth))
+  })
+  val registers = Reg(Vec(Parameters.PhysicalRegisters, UInt(Parameters.DataWidth)))
+
+  when(!reset.asBool) {
+    when(io.write_enable && io.write_address =/= 0.U) {
+      registers(io.write_address) := io.write_data
+    }
+  }
+
+  io.read_data1 := MuxCase(
+    registers(io.read_address1),
+    IndexedSeq(
+      (io.read_address1 === 0.U) -> 0.U,
+      (io.read_address1 === io.write_address && io.write_enable) -> io.write_data
+    )
+  )
+
+  io.read_data2 := MuxCase(
+    registers(io.read_address2),
+    IndexedSeq(
+      (io.read_address2 === 0.U) -> 0.U,
+      (io.read_address2 === io.write_address && io.write_enable) -> io.write_data
+    )
+  )
+
+  io.debug_read_data := MuxCase(
+    registers(io.debug_read_address),
+    IndexedSeq(
+      (io.debug_read_address === 0.U) -> 0.U,
+      (io.debug_read_address === io.write_address && io.write_enable) -> io.write_data
+    )
+  )
+
+}

lab4/src/main/scala/riscv/core/fivestage/WriteBack.scala

@@ -0,0 +1,40 @@
+// Copyright 2022 Canbin Huang
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.fivestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+class WriteBack extends Module {
+  val io = IO(new Bundle() {
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val alu_result = Input(UInt(Parameters.DataWidth))
+    val memory_read_data = Input(UInt(Parameters.DataWidth))
+    val regs_write_source = Input(UInt(2.W))
+    val csr_read_data = Input(UInt(Parameters.DataWidth))
+
+    val regs_write_data = Output(UInt(Parameters.DataWidth))
+  })
+  io.regs_write_data := MuxLookup(
+    io.regs_write_source,
+    io.alu_result,
+    IndexedSeq(
+      RegWriteSource.Memory -> io.memory_read_data,
+      RegWriteSource.CSR -> io.csr_read_data,
+      RegWriteSource.NextInstructionAddress -> (io.instruction_address + 4.U)
+    )
+  )
+}

lab4/src/main/scala/riscv/core/threestage/ALU.scala

@@ -0,0 +1,67 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import chisel3.experimental.ChiselEnum
+import chisel3.util._
+import riscv.Parameters
+
+object ALUFunctions extends ChiselEnum {
+  val zero, add, sub, sll, slt, xor, or, and, sr, sltu = Value
+}
+
+class ALU extends Module {
+  val io = IO(new Bundle {
+    val func = Input(ALUFunctions())
+
+    val op1 = Input(UInt(Parameters.DataWidth))
+    val op2 = Input(UInt(Parameters.DataWidth))
+
+    val result = Output(UInt(Parameters.DataWidth))
+  })
+
+  io.result := 0.U
+  switch(io.func) {
+    is(ALUFunctions.add) {
+      io.result := io.op1 + io.op2
+    }
+    is(ALUFunctions.sub) {
+      io.result := io.op1 - io.op2
+    }
+    is(ALUFunctions.sll) {
+      io.result := io.op1 << io.op2(4, 0)
+    }
+    is(ALUFunctions.slt) {
+      io.result := io.op1.asSInt < io.op2.asSInt
+    }
+    is(ALUFunctions.xor) {
+      io.result := io.op1 ^ io.op2
+    }
+    is(ALUFunctions.or) {
+      io.result := io.op1 | io.op2
+    }
+    is(ALUFunctions.and) {
+      io.result := io.op1 & io.op2
+    }
+    is(ALUFunctions.sr) {
+      io.result := io.op1 >> io.op2(4, 0)
+    }
+    is(ALUFunctions.sltu) {
+      io.result := io.op1 < io.op2
+    }
+  }
+
+}

lab4/src/main/scala/riscv/core/threestage/ALUControl.scala

@@ -0,0 +1,77 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import chisel3.util._
+
+class ALUControl extends Module {
+  val io = IO(new Bundle {
+    val opcode = Input(UInt(7.W))
+    val funct3 = Input(UInt(3.W))
+    val funct7 = Input(UInt(7.W))
+
+    val alu_funct = Output(ALUFunctions())
+  })
+
+  io.alu_funct := ALUFunctions.zero
+
+  switch(io.opcode) {
+    is(InstructionTypes.I) {
+      io.alu_funct := MuxLookup(
+        io.funct3,
+        ALUFunctions.zero,
+        IndexedSeq(
+          InstructionsTypeI.addi -> ALUFunctions.add,
+          InstructionsTypeI.slli -> ALUFunctions.sll,
+          InstructionsTypeI.slti -> ALUFunctions.slt,
+          InstructionsTypeI.sltiu -> ALUFunctions.sltu,
+          InstructionsTypeI.xori -> ALUFunctions.xor,
+          InstructionsTypeI.ori -> ALUFunctions.or,
+          InstructionsTypeI.andi -> ALUFunctions.and,
+          InstructionsTypeI.sri -> ALUFunctions.sr,
+        ),
+      )
+    }
+    is(InstructionTypes.RM) {
+      io.alu_funct := MuxLookup(
+        io.funct3,
+        ALUFunctions.zero,
+        IndexedSeq(
+          InstructionsTypeR.add_sub -> Mux(io.funct7(5), ALUFunctions.sub, ALUFunctions.add),
+          InstructionsTypeR.sll -> ALUFunctions.sll,
+          InstructionsTypeR.slt -> ALUFunctions.slt,
+          InstructionsTypeR.sltu -> ALUFunctions.sltu,
+          InstructionsTypeR.xor -> ALUFunctions.xor,
+          InstructionsTypeR.or -> ALUFunctions.or,
+          InstructionsTypeR.and -> ALUFunctions.and,
+          InstructionsTypeR.sr -> ALUFunctions.sr,
+        ),
+      )
+    }
+    is(Instructions.jal) {
+      io.alu_funct := ALUFunctions.add
+    }
+    is(Instructions.jalr) {
+      io.alu_funct := ALUFunctions.add
+    }
+    is(Instructions.lui) {
+      io.alu_funct := ALUFunctions.add
+    }
+    is(Instructions.auipc) {
+      io.alu_funct := ALUFunctions.add
+    }
+  }
+}

lab4/src/main/scala/riscv/core/threestage/CLINT.scala

@@ -0,0 +1,183 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+object InterruptStatus {
+  val None = 0x0.U(8.W)
+  val Timer0 = 0x1.U(8.W)
+  val Ret = 0xFF.U(8.W)
+}
+
+object InterruptEntry {
+  val Timer0 = 0x4.U(8.W)
+}
+
+object InterruptState {
+  val Idle = 0x0.U
+  val SyncAssert = 0x1.U
+  val AsyncAssert = 0x2.U
+  val MRET = 0x3.U
+}
+
+object CSRState {
+  val Idle = 0x0.U
+  val MSTATUS = 0x1.U
+  val MEPC = 0x2.U
+  val MRET = 0x3.U
+  val MCAUSE = 0x4.U
+}
+
+// Core Local Interrupt Controller
+class CLINT extends Module {
+  val io = IO(new Bundle {
+    // Interrupt signals from peripherals
+    val interrupt_flag = Input(UInt(Parameters.InterruptFlagWidth))
+
+    // Current instruction from instruction decode
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address_id = Input(UInt(Parameters.AddrWidth))
+
+    val jump_flag = Input(Bool())
+    val jump_address = Input(UInt(Parameters.AddrWidth))
+
+    val csr_mtvec = Input(UInt(Parameters.DataWidth))
+    val csr_mepc = Input(UInt(Parameters.DataWidth))
+    val csr_mstatus = Input(UInt(Parameters.DataWidth))
+
+    // Is global interrupt enabled (from MSTATUS)?
+    val interrupt_enable = Input(Bool())
+
+    val ctrl_stall_flag = Output(Bool())
+
+    val csr_reg_write_enable = Output(Bool())
+    val csr_reg_write_address = Output(UInt(Parameters.CSRRegisterAddrWidth))
+    val csr_reg_write_data = Output(UInt(Parameters.DataWidth))
+
+    val ex_interrupt_handler_address = Output(UInt(Parameters.AddrWidth))
+    val ex_interrupt_assert = Output(Bool())
+  })
+
+  val interrupt_state = WireInit(0.U)
+  val csr_state = RegInit(CSRState.Idle)
+  val instruction_address = RegInit(UInt(Parameters.AddrWidth), 0.U)
+  val cause = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val interrupt_assert = RegInit(Bool(), false.B)
+  val interrupt_handler_address = RegInit(UInt(Parameters.AddrWidth), 0.U)
+  val csr_reg_write_enable = RegInit(Bool(), false.B)
+  val csr_reg_write_address = RegInit(UInt(Parameters.CSRRegisterAddrWidth), 0.U)
+  val csr_reg_write_data = RegInit(UInt(Parameters.DataWidth), 0.U)
+
+  io.ctrl_stall_flag := interrupt_state =/= InterruptState.Idle || csr_state =/= CSRState.Idle
+
+  // Interrupt FSM
+  when(io.instruction === InstructionsEnv.ecall || io.instruction === InstructionsEnv.ebreak) {
+    interrupt_state := InterruptState.SyncAssert
+  }.elsewhen(io.interrupt_flag =/= InterruptStatus.None && io.interrupt_enable) {
+    interrupt_state := InterruptState.AsyncAssert
+  }.elsewhen(io.instruction === InstructionsRet.mret) {
+    interrupt_state := InterruptState.MRET
+  }.otherwise {
+    interrupt_state := InterruptState.Idle
+  }
+
+  // CSR FSM
+  when(csr_state === CSRState.Idle) {
+    when(interrupt_state === InterruptState.SyncAssert) {
+      // Synchronous Interrupt
+      csr_state := CSRState.MEPC
+      instruction_address := Mux(
+        io.jump_flag,
+        io.jump_address - 4.U,
+        io.instruction_address_id
+      )
+
+      cause := MuxLookup(
+        io.instruction,
+        10.U,
+        IndexedSeq(
+          InstructionsEnv.ecall -> 11.U,
+          InstructionsEnv.ebreak -> 3.U,
+        )
+      )
+    }.elsewhen(interrupt_state === InterruptState.AsyncAssert) {
+      // Asynchronous Interrupt
+      cause := 0x8000000BL.U
+      when(io.interrupt_flag(0)) {
+        cause := 0x80000007L.U
+      }
+      csr_state := CSRState.MEPC
+      instruction_address := Mux(
+        io.jump_flag,
+        io.jump_address,
+        io.instruction_address_id,
+      )
+    }.elsewhen(interrupt_state === InterruptState.MRET) {
+      // Interrupt Return
+      csr_state := CSRState.MRET
+    }
+  }.elsewhen(csr_state === CSRState.MEPC) {
+    csr_state := CSRState.MSTATUS
+  }.elsewhen(csr_state === CSRState.MSTATUS) {
+    csr_state := CSRState.MCAUSE
+  }.elsewhen(csr_state === CSRState.MCAUSE) {
+    csr_state := CSRState.Idle
+  }.elsewhen(csr_state === CSRState.MRET) {
+    csr_state := CSRState.Idle
+  }.otherwise {
+    csr_state := CSRState.Idle
+  }
+
+  csr_reg_write_enable := csr_state =/= CSRState.Idle
+  csr_reg_write_address := Cat(Fill(20, 0.U(1.W)), MuxLookup(
+    csr_state,
+    0.U(Parameters.CSRRegisterAddrWidth),
+    IndexedSeq(
+      CSRState.MEPC -> CSRRegister.MEPC,
+      CSRState.MCAUSE -> CSRRegister.MCAUSE,
+      CSRState.MSTATUS -> CSRRegister.MSTATUS,
+      CSRState.MRET -> CSRRegister.MSTATUS,
+    )
+  ))
+  csr_reg_write_data := MuxLookup(
+    csr_state,
+    0.U(Parameters.DataWidth),
+    IndexedSeq(
+      CSRState.MEPC -> instruction_address,
+      CSRState.MCAUSE -> cause,
+      CSRState.MSTATUS -> Cat(io.csr_mstatus(31, 4), 0.U(1.W), io.csr_mstatus(2, 0)),
+      CSRState.MRET -> Cat(io.csr_mstatus(31, 4), io.csr_mstatus(7), io.csr_mstatus(2, 0)),
+    )
+  )
+  io.csr_reg_write_enable := csr_reg_write_enable
+  io.csr_reg_write_address := csr_reg_write_address
+  io.csr_reg_write_data := csr_reg_write_data
+
+  interrupt_assert := csr_state === CSRState.MCAUSE || csr_state === CSRState.MRET
+  interrupt_handler_address := MuxLookup(
+    csr_state,
+    0.U(Parameters.AddrWidth),
+    IndexedSeq(
+      CSRState.MCAUSE -> io.csr_mtvec,
+      CSRState.MRET -> io.csr_mepc,
+    )
+  )
+
+  io.ex_interrupt_assert := interrupt_assert
+  io.ex_interrupt_handler_address := interrupt_handler_address
+}

lab4/src/main/scala/riscv/core/threestage/CPU.scala

@@ -0,0 +1,167 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import bus.{AXI4LiteChannels, AXI4LiteMaster}
+import chisel3._
+import riscv.Parameters
+import riscv.core.CPUBundle
+
+class CPU extends Module {
+  val io = IO(new CPUBundle)
+
+  val ctrl = Module(new Control)
+  val regs = Module(new RegisterFile)
+  val inst_fetch = Module(new InstructionFetch)
+  val if2id = Module(new IF2ID)
+  val id = Module(new InstructionDecode)
+  val id2ex = Module(new ID2EX)
+  val ex = Module(new Execute)
+  val clint = Module(new CLINT)
+  val csr_regs = Module(new CSR)
+  val axi4_master = Module(new AXI4LiteMaster(Parameters.AddrBits, Parameters.DataBits))
+
+  axi4_master.io.channels <> io.axi4_channels
+  io.debug(0) := ex.io.reg1_data
+  io.debug(1) := ex.io.reg2_data
+  io.debug(2) := ex.io.instruction_address
+  io.debug(3) := ex.io.instruction
+  io.debug(4) := ex.io.ctrl_jump_flag
+  io.debug(5) := ex.io.ctrl_jump_address
+  io.bus_busy := axi4_master.io.bundle.busy
+
+  // The EX module takes precedence over IF (but let the previous fetch finish)
+  val ex_granted = RegInit(false.B)
+  when(ex_granted) {
+    inst_fetch.io.instruction_valid := false.B
+    io.bus_address := ex.io.bus.address
+    axi4_master.io.bundle.read := ex.io.bus.read
+    axi4_master.io.bundle.address := ex.io.bus.address
+    axi4_master.io.bundle.write := ex.io.bus.write
+    axi4_master.io.bundle.write_data := ex.io.bus.write_data
+    axi4_master.io.bundle.write_strobe := ex.io.bus.write_strobe
+    when(!ex.io.bus.request) {
+      ex_granted := false.B
+    }
+  }.otherwise {
+    // Default to fetch instructions from main memory
+    ex_granted := false.B
+    axi4_master.io.bundle.read := !axi4_master.io.bundle.busy && !axi4_master.io.bundle.read_valid && !ex.io.bus.request
+    axi4_master.io.bundle.address := inst_fetch.io.bus_address
+    io.bus_address := inst_fetch.io.bus_address
+    axi4_master.io.bundle.write := false.B
+    axi4_master.io.bundle.write_data := 0.U
+    axi4_master.io.bundle.write_strobe := VecInit(Seq.fill(Parameters.WordSize)(false.B))
+  }
+
+  when(ex.io.bus.request) {
+    when(!axi4_master.io.bundle.busy && !axi4_master.io.bundle.read_valid) {
+      ex_granted := true.B
+    }
+  }
+
+  inst_fetch.io.instruction_valid := io.instruction_valid && axi4_master.io.bundle.read_valid && !ex_granted
+  inst_fetch.io.bus_data := axi4_master.io.bundle.read_data
+
+  ex.io.bus.read_data := axi4_master.io.bundle.read_data
+  ex.io.bus.read_valid := axi4_master.io.bundle.read_valid
+  ex.io.bus.write_valid := axi4_master.io.bundle.write_valid
+  ex.io.bus.busy := axi4_master.io.bundle.busy
+  ex.io.bus.granted := ex_granted
+
+  ctrl.io.jump_flag := ex.io.ctrl_jump_flag
+  ctrl.io.jump_address := ex.io.ctrl_jump_address
+  ctrl.io.stall_flag_if := inst_fetch.io.ctrl_stall_flag
+  ctrl.io.stall_flag_ex := ex.io.ctrl_stall_flag
+  ctrl.io.stall_flag_id := id.io.ctrl_stall_flag
+  ctrl.io.stall_flag_clint := clint.io.ctrl_stall_flag
+  ctrl.io.stall_flag_bus := io.stall_flag_bus
+
+  regs.io.write_enable := ex.io.regs_write_enable
+  regs.io.write_address := ex.io.regs_write_address
+  regs.io.write_data := ex.io.regs_write_data
+  regs.io.read_address1 := id.io.regs_reg1_read_address
+  regs.io.read_address2 := id.io.regs_reg2_read_address
+
+  regs.io.debug_read_address := io.debug_read_address
+  io.debug_read_data := regs.io.debug_read_data
+
+  inst_fetch.io.jump_flag_ctrl := ctrl.io.pc_jump_flag
+  inst_fetch.io.jump_address_ctrl := ctrl.io.pc_jump_address
+  inst_fetch.io.stall_flag_ctrl := ctrl.io.output_stall_flag
+
+  if2id.io.instruction := inst_fetch.io.id_instruction
+  if2id.io.instruction_address := inst_fetch.io.id_instruction_address
+  if2id.io.stall_flag := ctrl.io.output_stall_flag
+  if2id.io.jump_flag := ctrl.io.pc_jump_flag
+  if2id.io.interrupt_flag := io.interrupt_flag
+
+  id.io.reg1_data := regs.io.read_data1
+  id.io.reg2_data := regs.io.read_data2
+  id.io.instruction := if2id.io.output_instruction
+  id.io.instruction_address := if2id.io.output_instruction_address
+  id.io.csr_read_data := csr_regs.io.id_reg_data
+
+  id2ex.io.instruction := id.io.ex_instruction
+  id2ex.io.instruction_address := id.io.ex_instruction_address
+  id2ex.io.csr_read_data := id.io.ex_csr_read_data
+  id2ex.io.csr_write_enable := id.io.ex_csr_write_enable
+  id2ex.io.csr_write_address := id.io.ex_csr_write_address
+  id2ex.io.op1 := id.io.ex_op1
+  id2ex.io.op2 := id.io.ex_op2
+  id2ex.io.op1_jump := id.io.ex_op1_jump
+  id2ex.io.op2_jump := id.io.ex_op2_jump
+  id2ex.io.reg1_data := id.io.ex_reg1_data
+  id2ex.io.reg2_data := id.io.ex_reg2_data
+  id2ex.io.regs_write_enable := id.io.ex_reg_write_enable
+  id2ex.io.regs_write_address := id.io.ex_reg_write_address
+  id2ex.io.stall_flag := ctrl.io.output_stall_flag
+  id2ex.io.jump_flag := ctrl.io.pc_jump_flag
+
+  ex.io.instruction := id2ex.io.output_instruction
+  ex.io.instruction_address := id2ex.io.output_instruction_address
+  ex.io.csr_reg_data_id := id2ex.io.output_csr_read_data
+  ex.io.csr_reg_write_enable_id := id2ex.io.output_csr_write_enable
+  ex.io.csr_reg_write_address_id := id2ex.io.output_csr_write_address
+  ex.io.op1 := id2ex.io.output_op1
+  ex.io.op2 := id2ex.io.output_op2
+  ex.io.op1_jump := id2ex.io.output_op1_jump
+  ex.io.op2_jump := id2ex.io.output_op2_jump
+  ex.io.reg1_data := id2ex.io.output_reg1_data
+  ex.io.reg2_data := id2ex.io.output_reg2_data
+  ex.io.regs_write_enable_id := id2ex.io.output_regs_write_enable
+  ex.io.regs_write_address_id := id2ex.io.output_regs_write_address
+  ex.io.interrupt_assert := clint.io.ex_interrupt_assert
+  ex.io.interrupt_handler_address := clint.io.ex_interrupt_handler_address
+
+  clint.io.instruction := id.io.ex_instruction
+  clint.io.instruction_address_id := id.io.instruction_address
+  clint.io.jump_flag := ex.io.ctrl_jump_flag
+  clint.io.jump_address := ex.io.ctrl_jump_address
+  clint.io.csr_mepc := csr_regs.io.clint_csr_mepc
+  clint.io.csr_mtvec := csr_regs.io.clint_csr_mtvec
+  clint.io.csr_mstatus := csr_regs.io.clint_csr_mstatus
+  clint.io.interrupt_enable := csr_regs.io.interrupt_enable
+  clint.io.interrupt_flag := if2id.io.output_interrupt_flag
+
+  csr_regs.io.reg_write_enable_ex := ex.io.csr_reg_write_enable
+  csr_regs.io.reg_write_address_ex := ex.io.csr_reg_write_address
+  csr_regs.io.reg_write_data_ex := ex.io.csr_reg_write_data
+  csr_regs.io.reg_read_address_id := id.io.csr_read_address
+  csr_regs.io.reg_write_enable_clint := clint.io.csr_reg_write_enable
+  csr_regs.io.reg_write_address_clint := clint.io.csr_reg_write_address
+  csr_regs.io.reg_write_data_clint := clint.io.csr_reg_write_data
+  csr_regs.io.reg_read_address_clint := 0.U
+}

lab4/src/main/scala/riscv/core/threestage/CSR.scala

@@ -0,0 +1,126 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+
+object CSRRegister {
+  // Refer to Spec. Vol.II Page 8-10
+  val CycleL = 0xc00.U(Parameters.CSRRegisterAddrWidth)
+  val CycleH = 0xc80.U(Parameters.CSRRegisterAddrWidth)
+  val MTVEC = 0x305.U(Parameters.CSRRegisterAddrWidth)
+  val MCAUSE = 0x342.U(Parameters.CSRRegisterAddrWidth)
+  val MEPC = 0x341.U(Parameters.CSRRegisterAddrWidth)
+  val MIE = 0x304.U(Parameters.CSRRegisterAddrWidth)
+  val MSTATUS = 0x300.U(Parameters.CSRRegisterAddrWidth)
+  val MSCRATCH = 0x340.U(Parameters.CSRRegisterAddrWidth)
+}
+
+class CSR extends Module {
+  val io = IO(new Bundle {
+    val reg_write_enable_ex = Input(Bool())
+    val reg_read_address_id = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val reg_write_address_ex = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val reg_write_data_ex = Input(UInt(Parameters.DataWidth))
+
+    val reg_write_enable_clint = Input(Bool())
+    val reg_read_address_clint = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val reg_write_address_clint = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val reg_write_data_clint = Input(UInt(Parameters.DataWidth))
+
+    val interrupt_enable = Output(Bool())
+
+    val id_reg_data = Output(UInt(Parameters.DataWidth))
+
+    val clint_reg_data = Output(UInt(Parameters.DataWidth))
+    val clint_csr_mtvec = Output(UInt(Parameters.DataWidth))
+    val clint_csr_mepc = Output(UInt(Parameters.DataWidth))
+    val clint_csr_mstatus = Output(UInt(Parameters.DataWidth))
+  })
+
+
+  val cycles = RegInit(UInt(64.W), 0.U)
+  val mtvec = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mcause = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mepc = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mie = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mstatus = RegInit(UInt(Parameters.DataWidth), 0.U)
+  val mscratch = RegInit(UInt(Parameters.DataWidth), 0.U)
+
+  cycles := cycles + 1.U
+  io.clint_csr_mtvec := mtvec
+  io.clint_csr_mepc := mepc
+  io.clint_csr_mstatus := mstatus
+  io.interrupt_enable := mstatus(3) === 1.U
+
+  val reg_write_address = Wire(UInt(Parameters.CSRRegisterAddrWidth))
+  val reg_write_data = Wire(UInt(Parameters.DataWidth))
+  reg_write_address := 0.U
+  reg_write_data := 0.U
+
+  val reg_read_address = Wire(UInt(Parameters.CSRRegisterAddrWidth))
+  val reg_read_data = Wire(UInt(Parameters.DataWidth))
+  reg_read_address := 0.U
+  reg_read_data := 0.U
+
+  when(io.reg_write_enable_ex) {
+    reg_write_address := io.reg_write_address_ex(11, 0)
+    reg_write_data := io.reg_write_data_ex
+  }.elsewhen(io.reg_write_enable_clint) {
+    reg_write_address := io.reg_write_address_clint(11, 0)
+    reg_write_data := io.reg_write_data_clint
+  }
+
+  when(reg_write_address === CSRRegister.MTVEC) {
+    mtvec := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MCAUSE) {
+    mcause := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MEPC) {
+    mepc := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MIE) {
+    mie := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MSTATUS) {
+    mstatus := reg_write_data
+  }.elsewhen(reg_write_address === CSRRegister.MSCRATCH) {
+    mscratch := reg_write_data
+  }
+
+  val regLUT =
+    IndexedSeq(
+      CSRRegister.CycleL -> cycles(31, 0),
+      CSRRegister.CycleH -> cycles(63, 32),
+      CSRRegister.MTVEC -> mtvec,
+      CSRRegister.MCAUSE -> mcause,
+      CSRRegister.MEPC -> mepc,
+      CSRRegister.MIE -> mie,
+      CSRRegister.MSTATUS -> mstatus,
+      CSRRegister.MSCRATCH -> mscratch,
+    )
+
+  io.id_reg_data := MuxLookup(
+    io.reg_read_address_id,
+    0.U,
+    regLUT,
+  )
+
+  io.clint_reg_data := MuxLookup(
+    io.reg_read_address_clint,
+    0.U,
+    regLUT,
+  )
+}

lab4/src/main/scala/riscv/core/threestage/Cache.scala

@@ -0,0 +1,23 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+
+class Cache(cacheLineBytes: Int, associativity: Int, cacheLines: Int) extends Module {
+  val io = IO(new Bundle {
+
+  })
+}

lab4/src/main/scala/riscv/core/threestage/Control.scala

@@ -0,0 +1,55 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+object StallStates {
+  val None = 0.U
+  val PC = 1.U
+  val IF = 2.U
+  val ID = 3.U
+}
+
+class Control extends Module {
+  val io = IO(new Bundle {
+    val jump_flag = Input(Bool())
+    val stall_flag_if = Input(Bool())
+    val stall_flag_id = Input(Bool())
+    val stall_flag_ex = Input(Bool())
+    val stall_flag_clint = Input(Bool())
+    val stall_flag_bus = Input(Bool())
+    val jump_address = Input(UInt(Parameters.AddrWidth))
+
+    val output_stall_flag = Output(UInt(Parameters.StallStateWidth))
+
+    val pc_jump_flag = Output(Bool())
+    val pc_jump_address = Output(UInt(Parameters.AddrWidth))
+  })
+
+  io.pc_jump_flag := io.jump_flag
+  io.pc_jump_address := io.jump_address
+
+  io.output_stall_flag := MuxCase(
+    StallStates.None,
+    IndexedSeq(
+      (io.jump_flag || io.stall_flag_ex || io.stall_flag_clint) -> StallStates.ID,
+      io.stall_flag_id -> StallStates.IF,
+      (io.stall_flag_bus || io.stall_flag_if) -> StallStates.PC,
+    )
+  )
+}

lab4/src/main/scala/riscv/core/threestage/Execute.scala

@@ -0,0 +1,315 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import chisel3.experimental.ChiselEnum
+import chisel3.util._
+import riscv.Parameters
+import riscv.core.BusBundle
+
+object MemoryAccessStates extends ChiselEnum {
+  val Idle, Read, Write, ReadWrite = Value
+}
+
+class Execute extends Module {
+  val io = IO(new Bundle {
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val interrupt_assert = Input(Bool())
+    val interrupt_handler_address = Input(UInt(Parameters.AddrWidth))
+    val regs_write_enable_id = Input(Bool())
+    val regs_write_address_id = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val csr_reg_write_enable_id = Input(Bool())
+    val csr_reg_write_address_id = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val csr_reg_data_id = Input(UInt(Parameters.DataWidth))
+    val reg1_data = Input(UInt(Parameters.DataWidth))
+    val reg2_data = Input(UInt(Parameters.DataWidth))
+    val op1 = Input(UInt(Parameters.DataWidth))
+    val op2 = Input(UInt(Parameters.DataWidth))
+    val op1_jump = Input(UInt(Parameters.DataWidth))
+    val op2_jump = Input(UInt(Parameters.DataWidth))
+
+    val bus = new BusBundle
+
+    val regs_write_enable = Output(Bool())
+    val regs_write_address = Output(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val regs_write_data = Output(UInt(Parameters.DataWidth))
+
+    val ctrl_stall_flag = Output(Bool())
+    val ctrl_jump_flag = Output(Bool())
+    val ctrl_jump_address = Output(UInt(Parameters.AddrWidth))
+
+    val csr_reg_write_enable = Output(Bool())
+    val csr_reg_write_address = Output(UInt(Parameters.CSRRegisterAddrWidth))
+    val csr_reg_write_data = Output(UInt(Parameters.DataWidth))
+  })
+
+  val opcode = io.instruction(6, 0)
+  val funct3 = io.instruction(14, 12)
+  val funct7 = io.instruction(31, 25)
+  val rd = io.instruction(11, 7)
+  val uimm = io.instruction(19, 15)
+
+  val alu = Module(new ALU)
+  val alu_ctrl = Module(new ALUControl)
+
+  alu_ctrl.io.opcode := opcode
+  alu_ctrl.io.funct3 := funct3
+  alu_ctrl.io.funct7 := funct7
+  alu.io.func := alu_ctrl.io.alu_funct
+  alu.io.op1 := io.op1
+  alu.io.op2 := io.op2
+
+
+  val mem_read_address_index = (io.op1 + io.op2) (log2Up(Parameters.WordSize) - 1, 0).asUInt
+  val mem_write_address_index = (io.op1 + io.op2) (log2Up(Parameters.WordSize) - 1, 0).asUInt
+  val mem_access_state = RegInit(MemoryAccessStates.Idle)
+  val pending_interrupt = RegInit(false.B)
+  val pending_interrupt_handler_address = RegInit(Parameters.EntryAddress)
+
+  val jump_flag = Wire(Bool())
+  val jump_address = Wire(UInt(Parameters.AddrWidth))
+
+  io.ctrl_jump_flag := jump_flag || io.interrupt_assert
+  io.ctrl_jump_address := Mux(io.interrupt_assert, io.interrupt_handler_address, jump_address)
+
+  io.bus.read := false.B
+  io.bus.address := 0.U
+  io.bus.write_data := 0.U
+  io.bus.write_strobe := VecInit(Seq.fill(Parameters.WordSize)(false.B))
+  io.bus.write := false.B
+  io.regs_write_enable := io.regs_write_enable_id && !io.interrupt_assert
+  io.regs_write_address := io.regs_write_address_id
+  io.regs_write_data := 0.U
+  io.csr_reg_write_enable := io.csr_reg_write_enable_id && !io.interrupt_assert
+  io.csr_reg_write_address := io.csr_reg_write_address_id
+  io.csr_reg_write_data := 0.U
+  io.bus.request := false.B
+
+  def disable_control() = {
+    disable_stall()
+    disable_jump()
+  }
+
+  def disable_stall() = {
+    io.ctrl_stall_flag := false.B
+  }
+
+  def disable_jump() = {
+    jump_address := 0.U
+    jump_flag := false.B
+  }
+
+  def check_interrupt_during_bus_transaction() = {
+    // Store the interrupt and process later
+    when(io.interrupt_assert) {
+      pending_interrupt := true.B
+      pending_interrupt_handler_address := io.interrupt_handler_address
+      io.ctrl_jump_flag := false.B
+    }
+  }
+
+  def on_bus_transaction_finished() = {
+    mem_access_state := MemoryAccessStates.Idle
+    io.ctrl_stall_flag := false.B
+    when(pending_interrupt) {
+      pending_interrupt := false.B
+      io.ctrl_jump_flag := true.B
+      io.ctrl_jump_address := pending_interrupt_handler_address
+    }
+  }
+
+  when(opcode === InstructionTypes.I) {
+    disable_control()
+    val mask = (0xFFFFFFFFL.U >> io.instruction(24, 20)).asUInt
+    io.regs_write_data := alu.io.result
+    when(funct3 === InstructionsTypeI.sri) {
+      when(funct7(5).asBool) {
+        io.regs_write_data := alu.io.result & mask |
+          (Fill(32, io.op1(31)) & (~mask).asUInt).asUInt
+      }
+    }
+  }.elsewhen(opcode === InstructionTypes.RM) {
+    disable_control()
+    // TODO(howard): support mul and div
+    when(funct7 === 0.U || funct7 === 0x20.U) {
+      val mask = (0xFFFFFFFFL.U >> io.reg2_data(4, 0)).asUInt
+      io.regs_write_data := alu.io.result
+      when(funct3 === InstructionsTypeR.sr) {
+        when(funct7(5).asBool) {
+          io.regs_write_data := alu.io.result & mask |
+            (Fill(32, io.op1(31)) & (~mask).asUInt).asUInt
+        }
+      }
+    }
+  }.elsewhen(opcode === InstructionTypes.L) {
+    disable_control()
+
+    when(mem_access_state === MemoryAccessStates.Idle) {
+      // Start the read transaction when there is no interrupt asserted
+      // and the bus is available
+      when(!io.interrupt_assert) {
+        io.ctrl_stall_flag := true.B
+        io.regs_write_enable := false.B
+        io.bus.read := true.B
+        io.bus.address := io.op1 + io.op2
+        io.bus.request := true.B
+        when(io.bus.granted) {
+          mem_access_state := MemoryAccessStates.Read
+        }
+      }
+    }.elsewhen(mem_access_state === MemoryAccessStates.Read) {
+      check_interrupt_during_bus_transaction()
+      io.bus.request := true.B
+      io.bus.read := false.B
+      io.ctrl_stall_flag := true.B
+      io.bus.address := io.op1 + io.op2
+      when(io.bus.read_valid) {
+        io.regs_write_enable := true.B
+        val data = io.bus.read_data
+        io.regs_write_data := MuxLookup(
+          funct3,
+          0.U,
+          IndexedSeq(
+            InstructionsTypeL.lb -> MuxLookup(
+              mem_read_address_index,
+              Cat(Fill(24, data(31)), data(31, 24)),
+              IndexedSeq(
+                0.U -> Cat(Fill(24, data(7)), data(7, 0)),
+                1.U -> Cat(Fill(24, data(15)), data(15, 8)),
+                2.U -> Cat(Fill(24, data(23)), data(23, 16))
+              )
+            ),
+            InstructionsTypeL.lbu -> MuxLookup(
+              mem_read_address_index,
+              Cat(Fill(24, 0.U), data(31, 24)),
+              IndexedSeq(
+                0.U -> Cat(Fill(24, 0.U), data(7, 0)),
+                1.U -> Cat(Fill(24, 0.U), data(15, 8)),
+                2.U -> Cat(Fill(24, 0.U), data(23, 16))
+              )
+            ),
+            InstructionsTypeL.lh -> Mux(
+              mem_read_address_index === 0.U,
+              Cat(Fill(16, data(15)), data(15, 0)),
+              Cat(Fill(16, data(31)), data(31, 16))
+            ),
+            InstructionsTypeL.lhu -> Mux(
+              mem_read_address_index === 0.U,
+              Cat(Fill(16, 0.U), data(15, 0)),
+              Cat(Fill(16, 0.U), data(31, 16))
+            ),
+            InstructionsTypeL.lw -> data
+          )
+        )
+        on_bus_transaction_finished()
+      }
+    }
+  }.elsewhen(opcode === InstructionTypes.S) {
+    disable_control()
+
+    when(mem_access_state === MemoryAccessStates.Idle) {
+      // Start the write transaction when there is no interrupt asserted
+      // and the bus is available
+      when(!io.interrupt_assert) {
+        io.ctrl_stall_flag := true.B
+        io.bus.address := io.op1 + io.op2
+        io.bus.write_data := io.reg2_data
+        io.bus.write := true.B
+        io.bus.write_strobe := VecInit(Seq.fill(Parameters.WordSize)(false.B))
+        when(funct3 === InstructionsTypeS.sb) {
+          io.bus.write_strobe(mem_write_address_index) := true.B
+          io.bus.write_data := io.reg2_data(Parameters.ByteBits, 0) << (mem_write_address_index << log2Up(Parameters
+            .ByteBits).U)
+        }.elsewhen(funct3 === InstructionsTypeS.sh) {
+          when(mem_write_address_index === 0.U) {
+            for (i <- 0 until Parameters.WordSize / 2) {
+              io.bus.write_strobe(i) := true.B
+            }
+            io.bus.write_data := io.reg2_data(Parameters.WordSize / 2 * Parameters.ByteBits, 0)
+          }.otherwise {
+            for (i <- Parameters.WordSize / 2 until Parameters.WordSize) {
+              io.bus.write_strobe(i) := true.B
+            }
+            io.bus.write_data := io.reg2_data(Parameters.WordSize / 2 * Parameters.ByteBits, 0) << (Parameters
+              .WordSize / 2 * Parameters.ByteBits)
+          }
+        }.elsewhen(funct3 === InstructionsTypeS.sw) {
+          for (i <- 0 until Parameters.WordSize) {
+            io.bus.write_strobe(i) := true.B
+          }
+        }
+        io.bus.request := true.B
+        when(io.bus.granted) {
+          mem_access_state := MemoryAccessStates.Write
+        }
+      }
+    }.elsewhen(mem_access_state === MemoryAccessStates.Write) {
+      check_interrupt_during_bus_transaction()
+      io.bus.request := true.B
+      io.ctrl_stall_flag := true.B
+      io.bus.write := false.B
+      io.bus.address := io.op1 + io.op2
+      when(io.bus.write_valid) {
+        on_bus_transaction_finished()
+      }
+    }
+  }.elsewhen(opcode === InstructionTypes.B) {
+    disable_control()
+    jump_flag := MuxLookup(
+      funct3,
+      0.U,
+      IndexedSeq(
+        InstructionsTypeB.beq -> (io.op1 === io.op2),
+        InstructionsTypeB.bne -> (io.op1 =/= io.op2),
+        InstructionsTypeB.bltu -> (io.op1 < io.op2),
+        InstructionsTypeB.bgeu -> (io.op1 >= io.op2),
+        InstructionsTypeB.blt -> (io.op1.asSInt < io.op2.asSInt),
+        InstructionsTypeB.bge -> (io.op1.asSInt >= io.op2.asSInt)
+      )
+    )
+    jump_address := Fill(32, io.ctrl_jump_flag) & (io.op1_jump + io.op2_jump)
+  }.elsewhen(opcode === Instructions.jal || opcode === Instructions.jalr) {
+    disable_stall()
+    jump_flag := true.B
+    jump_address := io.op1_jump + io.op2_jump
+    io.regs_write_data := io.op1 + io.op2
+  }.elsewhen(opcode === Instructions.lui || opcode === Instructions.auipc) {
+    disable_control()
+    io.regs_write_data := io.op1 + io.op2
+  }.elsewhen(opcode === Instructions.csr) {
+    disable_control()
+    io.csr_reg_write_data := MuxLookup(funct3, 0.U, IndexedSeq(
+      InstructionsTypeCSR.csrrw -> io.reg1_data,
+      InstructionsTypeCSR.csrrc -> io.csr_reg_data_id.&((~io.reg1_data).asUInt),
+      InstructionsTypeCSR.csrrs -> io.csr_reg_data_id.|(io.reg1_data),
+      InstructionsTypeCSR.csrrwi -> Cat(0.U(27.W), uimm),
+      InstructionsTypeCSR.csrrci -> io.csr_reg_data_id.&((~Cat(0.U(27.W), uimm)).asUInt),
+      InstructionsTypeCSR.csrrsi -> io.csr_reg_data_id.|(Cat(0.U(27.W), uimm)),
+    ))
+    io.regs_write_data := MuxLookup(funct3, 0.U, IndexedSeq(
+      InstructionsTypeCSR.csrrw -> io.csr_reg_data_id,
+      InstructionsTypeCSR.csrrc -> io.csr_reg_data_id,
+      InstructionsTypeCSR.csrrs -> io.csr_reg_data_id,
+      InstructionsTypeCSR.csrrwi -> io.csr_reg_data_id,
+      InstructionsTypeCSR.csrrci -> io.csr_reg_data_id,
+      InstructionsTypeCSR.csrrsi -> io.csr_reg_data_id,
+    ))
+  }.otherwise {
+    disable_control()
+    io.regs_write_data := 0.U
+  }
+}

lab4/src/main/scala/riscv/core/threestage/ID2EX.scala

@@ -0,0 +1,132 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import riscv.Parameters
+
+class ID2EX extends Module {
+  val io = IO(new Bundle {
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val regs_write_enable = Input(Bool())
+    val regs_write_address = Input(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val reg1_data = Input(UInt(Parameters.DataWidth))
+    val reg2_data = Input(UInt(Parameters.DataWidth))
+    val op1 = Input(UInt(Parameters.DataWidth))
+    val op2 = Input(UInt(Parameters.DataWidth))
+    val op1_jump = Input(UInt(Parameters.DataWidth))
+    val op2_jump = Input(UInt(Parameters.DataWidth))
+    val csr_write_enable = Input(Bool())
+    val csr_write_address = Input(UInt(Parameters.CSRRegisterAddrWidth))
+    val csr_read_data = Input(UInt(Parameters.DataWidth))
+    val stall_flag = Input(UInt(Parameters.StallStateWidth))
+    val jump_flag = Input(Bool())
+
+    val output_instruction = Output(UInt(Parameters.DataWidth))
+    val output_instruction_address = Output(UInt(Parameters.AddrWidth))
+    val output_regs_write_enable = Output(Bool())
+    val output_regs_write_address = Output(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val output_reg1_data = Output(UInt(Parameters.DataWidth))
+    val output_reg2_data = Output(UInt(Parameters.DataWidth))
+    val output_op1 = Output(UInt(Parameters.DataWidth))
+    val output_op2 = Output(UInt(Parameters.DataWidth))
+    val output_op1_jump = Output(UInt(Parameters.DataWidth))
+    val output_op2_jump = Output(UInt(Parameters.DataWidth))
+    val output_csr_write_enable = Output(Bool())
+    val output_csr_write_address = Output(UInt(Parameters.CSRRegisterAddrWidth))
+    val output_csr_read_data = Output(UInt(Parameters.DataWidth))
+  })
+  val write_enable = io.stall_flag < StallStates.ID
+  val flush_enable = io.jump_flag
+
+  val instruction = Module(new PipelineRegister(defaultValue = InstructionsNop.nop))
+  instruction.io.in := io.instruction
+  instruction.io.write_enable := write_enable
+  instruction.io.flush_enable := flush_enable
+  io.output_instruction := instruction.io.out
+
+  val instruction_address = Module(new PipelineRegister(defaultValue = ProgramCounter.EntryAddress))
+  instruction_address.io.in := io.instruction_address
+  instruction_address.io.write_enable := write_enable
+  instruction_address.io.flush_enable := flush_enable
+  io.output_instruction_address := instruction_address.io.out
+
+  val regs_write_enable = Module(new PipelineRegister(1))
+  regs_write_enable.io.in := io.regs_write_enable
+  regs_write_enable.io.write_enable := write_enable
+  regs_write_enable.io.flush_enable := flush_enable
+  io.output_regs_write_enable := regs_write_enable.io.out
+
+  val regs_write_address = Module(new PipelineRegister(Parameters.PhysicalRegisterAddrBits))
+  regs_write_address.io.in := io.regs_write_address
+  regs_write_address.io.write_enable := write_enable
+  regs_write_address.io.flush_enable := flush_enable
+  io.output_regs_write_address := regs_write_address.io.out
+
+  val reg1_data = Module(new PipelineRegister())
+  reg1_data.io.in := io.reg1_data
+  reg1_data.io.write_enable := write_enable
+  reg1_data.io.flush_enable := flush_enable
+  io.output_reg1_data := reg1_data.io.out
+
+  val reg2_data = Module(new PipelineRegister())
+  reg2_data.io.in := io.reg2_data
+  reg2_data.io.write_enable := write_enable
+  reg2_data.io.flush_enable := flush_enable
+  io.output_reg2_data := reg2_data.io.out
+
+  val op1 = Module(new PipelineRegister())
+  op1.io.in := io.op1
+  op1.io.write_enable := write_enable
+  op1.io.flush_enable := flush_enable
+  io.output_op1 := op1.io.out
+
+  val op2 = Module(new PipelineRegister())
+  op2.io.in := io.op2
+  op2.io.write_enable := write_enable
+  op2.io.flush_enable := flush_enable
+  io.output_op2 := op2.io.out
+
+  val op1_jump = Module(new PipelineRegister())
+  op1_jump.io.in := io.op1_jump
+  op1_jump.io.write_enable := write_enable
+  op1_jump.io.flush_enable := flush_enable
+  io.output_op1_jump := op1_jump.io.out
+
+  val op2_jump = Module(new PipelineRegister())
+  op2_jump.io.in := io.op2_jump
+  op2_jump.io.write_enable := write_enable
+  op2_jump.io.flush_enable := flush_enable
+  io.output_op2_jump := op2_jump.io.out
+
+  val csr_write_enable = Module(new PipelineRegister())
+  csr_write_enable.io.in := io.csr_write_enable
+  csr_write_enable.io.write_enable := write_enable
+  csr_write_enable.io.flush_enable := flush_enable
+  io.output_csr_write_enable := csr_write_enable.io.out
+
+  val csr_write_address = Module(new PipelineRegister())
+  csr_write_address.io.in := io.csr_write_address
+  csr_write_address.io.write_enable := write_enable
+  csr_write_address.io.flush_enable := flush_enable
+  io.output_csr_write_address := csr_write_address.io.out
+
+  val csr_read_data = Module(new PipelineRegister())
+  csr_read_data.io.in := io.csr_read_data
+  csr_read_data.io.write_enable := write_enable
+  csr_read_data.io.flush_enable := flush_enable
+  io.output_csr_read_data := csr_read_data.io.out
+}

lab4/src/main/scala/riscv/core/threestage/IF2ID.scala

@@ -0,0 +1,53 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import riscv.Parameters
+
+class IF2ID extends Module {
+  val io = IO(new Bundle {
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val stall_flag = Input(UInt(Parameters.StallStateWidth))
+    val interrupt_flag = Input(UInt(Parameters.InterruptFlagWidth))
+    val jump_flag = Input(Bool())
+
+    val output_instruction = Output(UInt(Parameters.DataWidth))
+    val output_instruction_address = Output(UInt(Parameters.AddrWidth))
+    val output_interrupt_flag = Output(UInt(Parameters.InterruptFlagWidth))
+  })
+
+  val write_enable = io.stall_flag < StallStates.IF
+  val flush_enable = io.jump_flag
+
+  val instruction = Module(new PipelineRegister(defaultValue = InstructionsNop.nop))
+  instruction.io.in := io.instruction
+  instruction.io.write_enable := write_enable
+  instruction.io.flush_enable := flush_enable
+  io.output_instruction := instruction.io.out
+
+  val instruction_address = Module(new PipelineRegister(defaultValue = ProgramCounter.EntryAddress))
+  instruction_address.io.in := io.instruction_address
+  instruction_address.io.write_enable := write_enable
+  instruction_address.io.flush_enable := flush_enable
+  io.output_instruction_address := instruction_address.io.out
+
+  val interrupt_flag = Module(new PipelineRegister())
+  interrupt_flag.io.in := io.interrupt_flag
+  interrupt_flag.io.write_enable := write_enable
+  interrupt_flag.io.flush_enable := flush_enable
+  io.output_interrupt_flag := interrupt_flag.io.out
+}

lab4/src/main/scala/riscv/core/threestage/InstructionDecode.scala

@@ -0,0 +1,317 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import chisel3.util._
+import riscv.Parameters
+
+
+object InstructionTypes  {
+  val L = "b0000011".U
+  val I = "b0010011".U
+  val S = "b0100011".U
+  val RM = "b0110011".U
+  val B = "b1100011".U
+}
+
+object Instructions  {
+  val lui = "b0110111".U
+  val nop = "b0000001".U
+  val jal = "b1101111".U
+  val jalr = "b1100111".U
+  val auipc = "b0010111".U
+  val csr = "b1110011".U
+  val fence = "b0001111".U
+}
+
+object InstructionsTypeL  {
+  val lb = "b000".U
+  val lh = "b001".U
+  val lw = "b010".U
+  val lbu = "b100".U
+  val lhu = "b101".U
+}
+
+object InstructionsTypeI {
+  val addi = 0.U
+  val slli = 1.U
+  val slti = 2.U
+  val sltiu = 3.U
+  val xori = 4.U
+  val sri = 5.U
+  val ori = 6.U
+  val andi = 7.U
+}
+
+object InstructionsTypeS  {
+  val sb = "b000".U
+  val sh = "b001".U
+  val sw = "b010".U
+}
+
+object InstructionsTypeR  {
+  val add_sub = 0.U
+  val sll = 1.U
+  val slt = 2.U
+  val sltu = 3.U
+  val xor = 4.U
+  val sr = 5.U
+  val or = 6.U
+  val and = 7.U
+}
+
+object InstructionsTypeM  {
+  val mul = 0.U
+  val mulh = 1.U
+  val mulhsu = 2.U
+  val mulhum = 3.U
+  val div = 4.U
+  val divu = 5.U
+  val rem = 6.U
+  val remu = 7.U
+}
+
+object InstructionsTypeB  {
+  val beq = "b000".U
+  val bne = "b001".U
+  val blt = "b100".U
+  val bge = "b101".U
+  val bltu = "b110".U
+  val bgeu = "b111".U
+}
+
+object InstructionsTypeCSR  {
+  val csrrw = "b001".U
+  val csrrs = "b010".U
+  val csrrc = "b011".U
+  val csrrwi = "b101".U
+  val csrrsi = "b110".U
+  val csrrci = "b111".U
+}
+
+object InstructionsNop {
+  val nop = 0x00000013L.U(Parameters.DataWidth)
+}
+
+object InstructionsRet {
+  val mret = 0x30200073L.U(Parameters.DataWidth)
+  val ret = 0x00008067L.U(Parameters.DataWidth)
+}
+
+object InstructionsEnv {
+  val ecall = 0x00000073L.U(Parameters.DataWidth)
+  val ebreak = 0x00100073L.U(Parameters.DataWidth)
+}
+
+class InstructionDecode extends Module {
+  val io = IO(new Bundle {
+    val instruction = Input(UInt(Parameters.InstructionWidth))
+    val instruction_address = Input(UInt(Parameters.AddrWidth))
+    val reg1_data = Input(UInt(Parameters.DataWidth))
+    val reg2_data = Input(UInt(Parameters.DataWidth))
+
+    val csr_read_data = Input(UInt(Parameters.DataWidth))
+
+    val regs_reg1_read_address = Output(UInt(Parameters.PhysicalRegisterAddrWidth))
+    val regs_reg2_read_address = Output(UInt(Parameters.PhysicalRegisterAddrWidth))
+
+    val ctrl_stall_flag = Output(UInt(Parameters.StallStateWidth))
+
+    val ex_op1 = Output(UInt(Parameters.DataWidth))
+    val ex_op2 = Output(UInt(Parameters.DataWidth))
+    val ex_op1_jump = Output(UInt(Parameters.DataWidth))
+    val ex_op2_jump = Output(UInt(Parameters.DataWidth))
+    val ex_instruction = Output(UInt(Parameters.DataWidth))
+    val ex_instruction_address = Output(UInt(Parameters.AddrWidth))
+    val ex_reg1_data = Output(UInt(Parameters.DataWidth))
+    val ex_reg2_data = Output(UInt(Parameters.DataWidth))
+    val ex_reg_write_enable = Output(Bool())
+    val ex_reg_write_address = Output(UInt(Parameters.PhysicalRegisterAddrWidth))
+
+    val csr_read_address = Output(UInt(Parameters.CSRRegisterAddrWidth))
+    val ex_csr_write_enable = Output(Bool())
+    val ex_csr_write_address = Output(UInt(Parameters.CSRRegisterAddrWidth))
+    val ex_csr_write_data = Output(UInt(Parameters.DataWidth))
+    val ex_csr_read_data = Output(UInt(Parameters.DataWidth))
+  })
+  val opcode = io.instruction(6, 0)
+  val funct3 = io.instruction(14, 12)
+  val funct7 = io.instruction(31, 25)
+  val rd = io.instruction(11, 7)
+  val rs1 = io.instruction(19, 15)
+  val rs2 = io.instruction(24, 20)
+
+  def disable_regs() = {
+    disable_write()
+    io.regs_reg1_read_address := 0.U
+    io.regs_reg2_read_address := 0.U
+  }
+
+  def disable_write() = {
+    io.ex_reg_write_enable := false.B
+    io.ex_reg_write_address := 0.U
+  }
+
+  def enable_write(addr: UInt) = {
+    io.ex_reg_write_enable := true.B
+    io.ex_reg_write_address := addr
+  }
+
+  io.ex_instruction := io.instruction
+  io.ex_instruction_address := io.instruction_address
+  io.ex_reg1_data := io.reg1_data
+  io.ex_reg2_data := io.reg2_data
+  io.ex_op1 := 0.U
+  io.ex_op2 := 0.U
+  io.ex_op1_jump := 0.U
+  io.ex_op2_jump := 0.U
+  io.ctrl_stall_flag := false.B
+  io.csr_read_address := 0.U
+  io.ex_csr_read_data := io.csr_read_data
+  io.ex_csr_write_enable := false.B
+  io.ex_csr_write_data := 0.U
+  io.ex_csr_write_address := 0.U
+
+  when(opcode === InstructionTypes.L) {
+    when(
+      funct3 === InstructionsTypeL.lb ||
+        funct3 === InstructionsTypeL.lh ||
+        funct3 === InstructionsTypeL.lw ||
+        funct3 === InstructionsTypeL.lbu ||
+        funct3 === InstructionsTypeL.lhu
+    ) {
+      enable_write(rd)
+      io.regs_reg1_read_address := rs1
+      io.regs_reg2_read_address := 0.U
+      io.ex_op1 := io.reg1_data
+      io.ex_op2 := Cat(Fill(20, io.instruction(31)), io.instruction(31, 20))
+    }.otherwise {
+      disable_regs()
+    }
+  }.elsewhen(opcode === InstructionTypes.I) {
+    enable_write(rd)
+    io.regs_reg1_read_address := rs1
+    io.regs_reg2_read_address := 0.U
+    io.ex_op1 := io.reg1_data
+    io.ex_op2 := Cat(Fill(20, io.instruction(31)), io.instruction(31, 20))
+  }.elsewhen(opcode === InstructionTypes.S) {
+    when(funct3 === InstructionsTypeS.sb ||
+      funct3 === InstructionsTypeS.sh ||
+      funct3 === InstructionsTypeS.sw) {
+      disable_write()
+      io.regs_reg1_read_address := rs1
+      io.regs_reg2_read_address := rs2
+      io.ex_op1 := io.reg1_data
+      io.ex_op2 := Cat(Fill(20, io.instruction(31)), io.instruction(31, 25), io.instruction(11, 7))
+    }.otherwise {
+      disable_regs()
+    }
+  }.elsewhen(opcode === InstructionTypes.RM) {
+    when(funct7 === 0.U || funct7 === 0x20.U) {
+      enable_write(rd)
+      io.regs_reg1_read_address := rs1
+      io.regs_reg2_read_address := rs2
+      io.ex_op1 := io.reg1_data
+      io.ex_op2 := io.reg2_data
+    }.otherwise {
+      // TODO(howard): implement mul and div
+      disable_regs()
+    }
+  }.elsewhen(opcode === InstructionTypes.B) {
+    when(
+      funct3 === InstructionsTypeB.beq ||
+        funct3 === InstructionsTypeB.bne ||
+        funct3 === InstructionsTypeB.blt ||
+        funct3 === InstructionsTypeB.bge ||
+        funct3 === InstructionsTypeB.bltu ||
+        funct3 === InstructionsTypeB.bgeu
+    ) {
+      disable_write()
+      io.regs_reg1_read_address := rs1
+      io.regs_reg2_read_address := rs2
+      io.ex_op1 := io.reg1_data
+      io.ex_op2 := io.reg2_data
+      io.ex_op1_jump := io.instruction_address
+      io.ex_op2_jump := Cat(Fill(20, io.instruction(31)), io.instruction(7), io.instruction(30, 25), io.instruction
+      (11, 8), 0.U(1.W))
+    }.otherwise {
+      disable_regs()
+    }
+  }.elsewhen(opcode === Instructions.jal) {
+    enable_write(rd)
+    io.regs_reg1_read_address := 0.U
+    io.regs_reg2_read_address := 0.U
+    io.ex_op1 := io.instruction_address
+    io.ex_op2 := 4.U
+    io.ex_op1_jump := io.instruction_address
+    io.ex_op2_jump := Cat(Fill(12, io.instruction(31)), io.instruction(19, 12), io.instruction(20), io.instruction
+    (30, 21), 0.U(1.W))
+  }.elsewhen(opcode === Instructions.jalr) {
+    enable_write(rd)
+    io.regs_reg1_read_address := rs1
+    io.regs_reg2_read_address := 0.U
+    io.ex_op1 := io.instruction_address
+    io.ex_op2 := 4.U
+    io.ex_op1_jump := io.reg1_data
+    io.ex_op2_jump := Cat(Fill(20, io.instruction(31)), io.instruction(31, 20))
+  }.elsewhen(opcode === Instructions.lui) {
+    enable_write(rd)
+    io.regs_reg1_read_address := 0.U
+    io.regs_reg2_read_address := 0.U
+    io.ex_op1 := Cat(io.instruction(31, 12), Fill(12, 0.U(1.W)))
+    io.ex_op2 := 0.U
+  }.elsewhen(opcode === Instructions.auipc) {
+    enable_write(rd)
+    io.regs_reg1_read_address := 0.U
+    io.regs_reg2_read_address := 0.U
+    io.ex_op1 := io.instruction_address
+    io.ex_op2 := Cat(io.instruction(31, 12), Fill(12, 0.U(1.W)))
+  }.elsewhen(opcode === Instructions.csr) {
+    disable_regs()
+    io.csr_read_address := Cat(0.U(20.W), io.instruction(31, 20))
+    io.ex_csr_write_address := Cat(0.U(20.W), io.instruction(31, 20))
+    when(
+      funct3 === InstructionsTypeCSR.csrrc ||
+        funct3 === InstructionsTypeCSR.csrrs ||
+        funct3 === InstructionsTypeCSR.csrrw
+    ) {
+      io.regs_reg1_read_address := rs1
+      io.regs_reg2_read_address := 0.U
+      io.ex_reg_write_enable := true.B
+      io.ex_reg_write_address := rd
+      io.ex_csr_write_enable := true.B
+    }.elsewhen(
+      funct3 === InstructionsTypeCSR.csrrci ||
+        funct3 === InstructionsTypeCSR.csrrsi ||
+        funct3 === InstructionsTypeCSR.csrrwi
+    ) {
+      io.regs_reg1_read_address := 0.U
+      io.regs_reg2_read_address := 0.U
+      io.ex_reg_write_enable := true.B
+      io.ex_reg_write_address := rd
+      io.ex_csr_write_enable := true.B
+    }.otherwise {
+      io.ex_csr_write_enable := false.B
+      io.ex_csr_write_data := 0.U
+      io.ex_csr_write_address := 0.U
+    }
+  }.elsewhen(opcode === Instructions.nop) {
+    disable_regs()
+  }.otherwise {
+    disable_regs()
+  }
+
+}

lab4/src/main/scala/riscv/core/threestage/InstructionFetch.scala

@@ -0,0 +1,69 @@
+// Copyright 2021 Howard Lau
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package riscv.core.threestage
+
+import chisel3._
+import chisel3.util.MuxCase
+import riscv.Parameters
+
+object ProgramCounter {
+  val EntryAddress = Parameters.EntryAddress
+}
+
+class InstructionFetch extends Module {
+  val io = IO(new Bundle {
+    val stall_flag_ctrl = Input(Bool())
+    val jump_flag_ctrl = Input(Bool())
+    val jump_address_ctrl = Input(UInt(Parameters.AddrWidth))
+    val instruction_valid = Input(Bool())
+
+    val bus_request = Output(Bool())
+    val bus_address = Output(UInt(Parameters.AddrWidth))
+    val bus_data = Input(UInt(Parameters.InstructionWidth))
+    val bus_read = Output(Bool())
+
+    val ctrl_stall_flag = Output(Bool())
+    val id_instruction_address = Output(UInt(Parameters.AddrWidth))
+    val id_instruction = Output(UInt(Parameters.InstructionWidth))
+  })
+  val instruction_address = RegInit(ProgramCounter.EntryAddress)
+  val pending_jump = RegInit(false.B)
+  val pc = RegInit(ProgramCounter.EntryAddress)
+  io.bus_read := true.B
+  io.bus_request := true.B
+
+  pc := MuxCase(
+    pc + 4.U,
+    IndexedSeq(
+      io.jump_flag_ctrl -> io.jump_address_ctrl,
+      (io.stall_flag_ctrl >= StallStates.PC) -> pc
+    )
+  )
+  when(!io.instruction_valid) {
+    when(io.jump_flag_ctrl) {
+      pending_jump := true.B
+    }
+  }
+  when(io.instruction_valid) {
+    when(pending_jump) {
+      pending_jump := false.B
+    }
+  }
+  io.id_instruction := Mux(io.instruction_valid && !io.jump_flag_ctrl && !pending_jump, io.bus_data,
+    InstructionsNop.nop)
+  io.ctrl_stall_flag := !io.instruction_valid || pending_jump
+  io.id_instruction_address := pc
+  io.bus_address := pc
+}