环境
- Time 2023-07-27
- Zig 0.11.0-dev.4191+1bf16b172
- SLD2 2.28.1
前言
说明
参考资料：
- https://en.wikipedia.org/wiki/CHIP-8
- https://austinmorlan.com/posts/chip8_emulator/
- https://rsj217.github.io/chip8-py/
- https://github.com/Timendus/chip8-test-suite
其中最后一个提供了测试的套件，实现的过程中，可以检测哪些指令有问题，帮助很大。
目标
实现按键功能，其中涉及到指令 EX9E、EXA1、FX0A。
keypad.zig
Chip8 只支持 16 个按键，分别是 0x0 到 0xF，可以根据自己的喜好设置映射。
const c = @cImport(@cInclude("SDL.h"));
const std = @import("std");pub const Keypad = struct {buffer: [16]bool = std.mem.zeroes([16]bool),event: c.SDL_Event = undefined,pub fn poll(self: *Keypad) bool {while (c.SDL_PollEvent(&self.event) > 0) {if (self.event.type == c.SDL_QUIT) return false;const flag = if (self.event.type == c.SDL_KEYDOWN) true //else if (self.event.type == c.SDL_KEYUP) false //else continue;self.setBuffer(self.event.key.keysym.sym, flag);}return true;}fn setBuffer(self: *Keypad, code: i32, value: bool) void {switch (code) {c.SDLK_x => self.buffer[0] = value,c.SDLK_1 => self.buffer[1] = value,c.SDLK_2 => self.buffer[2] = value,c.SDLK_3 => self.buffer[3] = value,c.SDLK_q => self.buffer[4] = value,c.SDLK_w => self.buffer[5] = value,c.SDLK_e => self.buffer[6] = value,c.SDLK_a => self.buffer[7] = value,c.SDLK_s => self.buffer[8] = value,c.SDLK_d => self.buffer[9] = value,c.SDLK_z => self.buffer[10] = value,c.SDLK_c => self.buffer[11] = value,c.SDLK_4 => self.buffer[12] = value,c.SDLK_r => self.buffer[13] = value,c.SDLK_f => self.buffer[14] = value,c.SDLK_v => self.buffer[15] = value,else => return,}}
};
memory.zig
其它无关代码已省略，新增检查某个按键是否按下和哪个键被按下的方法。
pub fn isPress(self: *Memory, index: usize) bool {return self.keypad.buffer[index];
}pub fn getPress(self: *Memory) ?u8 {for (self.keypad.buffer, 0..) |code, index| {if (code) return @truncate(index);}return null;
}
0xE
0xE => {const isPress = memory.isPress(reg[ins.x]);if (ins.nn == 0x9E and isPress) self.next();if (ins.nn == 0xA1 and !isPress) self.next();},
0x0A
codef中的新增检查 0x0A的分支。
0x0A => if (memory.getPress()) |index| {self.register[ins.x] = index;} else self.back(),fn back(self: *CPU) void {self.pc -= 2;}
main.zig
const std = @import("std");
const chip8 = @import("chip8.zig");pub fn main() !void {// const rom = @embedFile("roms/1-chip8-logo.ch8");// const rom = @embedFile("roms/2-ibm-logo.ch8");// const rom = @embedFile("roms/3-corax+.ch8");// const rom = @embedFile("roms/4-flags.ch8");// const rom = @embedFile("roms/5-quirks.ch8");const rom = @embedFile("roms/6-keypad.ch8");var emulator = chip8.Emulator.new(rom);emulator.run();
}
启动
zig build run
效果
总结
实现了键盘按键的功能，测试时，需要将输入法调整成英文，不然只有数字生效，字母不生效。