init repo

lab1/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 (;;) ;
+}