mirror of
https://github.com/handsomezhuzhu/2025-yatcpu.git
synced 2026-02-20 20:10:14 +00:00
85 lines
2.6 KiB
Scala
85 lines
2.6 KiB
Scala
// Copyright 2022 Howard Lau
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package peripheral
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import chisel3.util.{MuxLookup, log2Up}
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import chisel3.{Bool, Bundle, Module, Mux, Output, UInt, Wire, _}
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import peripheral.ScreenInfo.{DisplayHorizontal, DisplayVertical}
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import riscv.Parameters
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object GlyphInfo {
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val glyphWidth = 8
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val glyphHeight = 16
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// ASCII printable characters start from here
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val spaceIndex = 1
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}
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object ScreenInfo {
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val DisplayHorizontal = 640
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val DisplayVertical = 480
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}
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object CharacterBufferInfo {
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val CharCols = DisplayHorizontal / GlyphInfo.glyphWidth
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val CharRows = DisplayVertical / GlyphInfo.glyphHeight
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val Chars = CharCols * CharRows
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}
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class CharacterDisplay extends Module {
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val io = IO(new Bundle() {
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val bundle = new RAMBundle()
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val x = Input(UInt(16.W))
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val y = Input(UInt(16.W))
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val video_on = Input(Bool())
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val rgb = Output(UInt(24.W))
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})
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val mem = Module(new BlockRAM(CharacterBufferInfo.Chars / Parameters.WordSize))
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mem.io.write_enable := io.bundle.write_enable
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mem.io.write_data := io.bundle.write_data
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mem.io.write_address := io.bundle.address
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mem.io.write_strobe := io.bundle.write_strobe
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mem.io.read_address := io.bundle.address
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io.bundle.read_data := mem.io.read_data
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val font_rom = Module(new FontROM)
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val row = (io.y >> log2Up(GlyphInfo.glyphHeight)).asUInt
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val col = (io.x >> log2Up(GlyphInfo.glyphWidth)).asUInt
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val char_index = (row * CharacterBufferInfo.CharCols.U) + col
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val offset = char_index(1, 0)
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val ch = Wire(UInt(8.W))
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mem.io.debug_read_address := char_index
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ch := MuxLookup(
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offset,
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0.U,
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IndexedSeq(
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0.U -> mem.io.debug_read_data(7, 0).asUInt,
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1.U -> mem.io.debug_read_data(15, 8).asUInt,
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2.U -> mem.io.debug_read_data(23, 16).asUInt,
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3.U -> mem.io.debug_read_data(31, 24).asUInt
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)
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)
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font_rom.io.glyph_index := Mux(ch >= 32.U, ch - 31.U, 0.U)
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font_rom.io.glyph_y := io.y(log2Up(GlyphInfo.glyphHeight) - 1, 0)
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// White if pixel_on and glyph pixel on
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val glyph_x = io.x(log2Up(GlyphInfo.glyphWidth) - 1, 0)
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io.rgb := Mux(io.video_on && font_rom.io.glyph_pixel_byte(glyph_x), 0xFFFFFF.U, 0.U)
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}
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