wa wemu 模拟器增加 VGA 设备

Author: chai2010

internal/native/wemu/device/vga/vga.go

@@ -0,0 +1,110 @@
+// Copyright (C) 2025 武汉凹语言科技有限公司
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+package vga
+
+import (
+	"fmt"
+)
+
+// 设备的默认映射地址
+const VGA_BASE = 0x100000
+
+// 显示器
+type VGA struct {
+	name    string
+	addr    uint64
+	width   int
+	height  int
+	data    []byte  // 内存数据
+	palette []byte  // data[:256*4]
+	screen  []uint8 // data[256*4:]
+}
+
+// 构造 VGA 显示器
+func NewVGA(name string, addr uint64, width, height int) *VGA {
+	p := &VGA{
+		name:   name,
+		addr:   addr,
+		width:  width,
+		height: height,
+		data:   make([]byte, 256*4+width*height),
+	}
+
+	p.palette = p.data[:256*4]
+	p.screen = p.data[256*4:]
+
+	for i := 0; i < 256; i++ {
+		p.palette[i+0] = uint8(i)
+		p.palette[i+1] = uint8(i)
+		p.palette[i+2] = uint8(i)
+		p.palette[i+3] = 255
+	}
+
+	return p
+}
+
+func (p *VGA) Name() string      { return p.name }
+func (p *VGA) AddrBegin() uint64 { return p.addr }
+func (p *VGA) AddrEnd() uint64   { return p.addr + uint64(len(p.data)) }
+
+// 读颜色表
+func (p *VGA) ReadPalette(offset uint64) uint32 {
+	v := uint32(p.palette[offset+2])       // B
+	v |= uint32(p.palette[offset+1]) << 8  // G
+	v |= uint32(p.palette[offset+0]) << 16 // R
+	v |= uint32(p.palette[offset+3]) << 24
+	return v
+}
+
+// 写颜色表
+func (p *VGA) WritePalette(offset uint64, value uint32) {
+	p.palette[offset+2] = uint8((value >> 0) & 0xFF)  // B
+	p.palette[offset+1] = uint8((value >> 8) & 0xFF)  // G
+	p.palette[offset+0] = uint8((value >> 16) & 0xFF) // R
+	p.palette[offset+3] = 255
+}
+
+// 读帧缓存
+func (p *VGA) ReadScreen(offset uint64) (value uint32) {
+	v := uint32(p.screen[offset+2])       // B
+	v |= uint32(p.screen[offset+1]) << 8  // G
+	v |= uint32(p.screen[offset+0]) << 16 // R
+	v |= uint32(p.screen[offset+3]) << 24
+	return v
+}
+
+// 写帧缓存(offset不是内存地址, 而是帧缓存内部偏移)
+func (vga *VGA) WriteScreen(offset uint64, value uint32) {
+	vga.screen[offset+0] = uint8(value & 0xFF)
+	vga.screen[offset+1] = uint8((value & 0xFF00) >> 8)
+	vga.screen[offset+2] = uint8((value & 0xFF0000) >> 16)
+	vga.screen[offset+3] = uint8((value & 0xFF000000) >> 24)
+}
+
+func (p *VGA) Read(addr, size uint64) (uint64, error) {
+	if addr < p.AddrBegin() || addr >= p.AddrEnd() {
+		return 0, fmt.Errorf("%s: bad address [0x%08X, 0x%x08X)", p.name, addr, addr+size)
+	}
+	switch off := addr - p.addr; true {
+	case off < 256*4:
+		return uint64(p.ReadPalette(off)), nil
+	default:
+		return uint64(p.ReadScreen(off)), nil
+	}
+}
+
+func (p *VGA) Write(addr, size, value uint64) error {
+	if addr < p.AddrBegin() || addr >= p.AddrEnd() {
+		return fmt.Errorf("%s: bad address [0x%08X, 0x%x08X)", p.name, addr, addr+size)
+	}
+
+	switch off := addr - p.addr; true {
+	case off < 256*4:
+		p.WritePalette(off, uint32(value))
+		return nil
+	default:
+		p.WriteScreen(off, uint32(value))
+		return nil
+	}
+}