Marto/chip8-emulator
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fixes

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This commit is contained in:
Martin Vrhovšek 2025-04-26 00:05:11 +02:00
parent 3652df31f4
commit fd386888f4
1 changed files with 26 additions and 27 deletions
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53
src/main.zig
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@ -4,7 +4,7 @@ const rl = @import("raylib");
const WIDTH = 64;
const HEIGHT = 32;
const SCALE = 15;
const FREQUENCY = 30;
const FREQUENCY = 60;
const MEMORY_SIZE = 4096;
const FONT_START = 0x050;
@ -27,7 +27,7 @@ const Emulator = struct {
prng: std.Random.Xoshiro256,
pub fn init(allocator: std.mem.Allocator) !Emulator {
return Emulator{ .screen = clearScreen(), .memory = try initMemory(allocator), .stack = std.ArrayList(u16).init(allocator), .v = std.mem.zeroes([16]u8), .i = 0, .key_pressed = 0, .pc = PROGRAM_START, .delay_timer = FREQUENCY, .sound_timer = 0, .legacy = true, .legacy_memory = false, .add_index_exception = false, .prng = std.Random.DefaultPrng.init(blk: {
return Emulator{ .screen = clearScreen(), .memory = try initMemory(allocator), .stack = std.ArrayList(u16).init(allocator), .v = std.mem.zeroes([16]u8), .i = 0, .key_pressed = 0, .pc = PROGRAM_START, .delay_timer = 0, .sound_timer = 0, .legacy = true, .legacy_memory = false, .add_index_exception = false, .prng = std.Random.DefaultPrng.init(blk: {
var seed: u64 = undefined;
try std.posix.getrandom(std.mem.asBytes(&seed));
break :blk seed;
@ -40,9 +40,8 @@ const Emulator = struct {
pub fn instructionCycle(self: *Emulator) !void {
const instruction: u16 = @as(u16, self.memory[self.pc]) << 8 | @as(u16, self.memory[self.pc + 1]);
var bd: [10]u8 = undefined;
_ = try std.fmt.bufPrint(&bd, "{X:0>4}", .{instruction});
std.debug.print("Instruction: {s}\n\n", .{bd});
// var bd: [10]u8 = undefined;
// _ = try std.fmt.bufPrint(&bd, "{X:0>4}", .{instruction});
const first: u8 = @truncate(instruction >> 12);
const x: u8 = @truncate((instruction >> 8) & 0xF);
@ -126,9 +125,9 @@ const Emulator = struct {
},
0x6 => {
// shifting v[x] right and saving the dropped bit into V[0xF]
// if (self.legacy) {
// self.v[x] = self.v[y];
// }
if (self.legacy) {
self.v[x] = self.v[y];
}
self.v[0xF] = self.v[x] & 0x1;
self.v[x] >>= 1;
@ -141,11 +140,11 @@ const Emulator = struct {
},
0xE => {
// shifting v[x] left and saving the dropped bit into V[0xF]
// if (self.legacy) {
// self.v[x] = self.v[y];
// }
if (self.legacy) {
self.v[x] = self.v[y];
}
self.v[0xF] = (self.v[x] & 0x80) >> 7;
self.v[0xF] = self.v[x] >> 7;
self.v[x] <<= 1;
},
else => {},
@ -195,12 +194,12 @@ const Emulator = struct {
self.v[0xF] = 1;
}
x_coord += 1;
if (x_coord >= WIDTH) break;
x_coord = (x_coord + 1) % WIDTH;
// if (x_coord >= WIDTH) break;
}
x_coord = self.v[x] % WIDTH;
y_coord += 1;
if (y_coord >= HEIGHT) break;
y_coord = (y_coord + 1) % HEIGHT;
// if (y_coord >= HEIGHT) break;
}
},
0xE => {
@ -217,13 +216,10 @@ const Emulator = struct {
},
0xF => {
switch (nn) {
// set delay
// set vx to delay
0x07 => self.v[x] = self.delay_timer,
0x15 => {
// set delay, adjust fps
self.delay_timer = self.v[x];
rl.setTargetFPS(self.delay_timer);
},
// set delay
0x15 => self.delay_timer = self.v[x],
// set sound timer
0x18 => self.sound_timer = self.v[x],
0x1E => {
@ -399,16 +395,19 @@ pub fn main() !void {
rl.initWindow(WIDTH * SCALE, HEIGHT * SCALE, "CHIP-8 Emulator");
defer rl.closeWindow();
rl.setTargetFPS(chip8.delay_timer);
var cycle_count: usize = 0;
rl.setTargetFPS(FREQUENCY);
while (!rl.windowShouldClose()) {
cycle_count += 1;
std.debug.print("Cycle count: {d}\n", .{cycle_count});
chip8.getInput();
try chip8.instructionCycle();
chip8.draw();
// todo sound timer decrease i guess
if (chip8.delay_timer > 0) chip8.delay_timer -= 1;
if (chip8.sound_timer > 0) {
// todo sound implementation
chip8.sound_timer -= 1;
}
}
}