src/emu.zig

@@ -9,19 +9,12 @@ const Timer = std.time.Timer;
 const Thread = std.Thread;
 const Atomic = std.atomic.Atomic;
 
-// 228 Lines which consist of 308 dots (which are 4 cycles long)
-const cycles_per_frame: u64 = 228 * (308 * 4); //280896
-const clock_rate: u64 = 1 << 24; // 16.78MHz 
-
-// TODO: Don't truncate this, be more accurate w/ timing
-// 59.6046447754ns (truncated to just 59ns)
+// One frame operates at 59.7275005696Hz
+const cycles_per_frame: u64 = 228 * (308 * 4);
+const clock_rate: u64 = 1 << 24;
 const clock_period: u64 = std.time.ns_per_s / clock_rate;
 const frame_period = (clock_period * cycles_per_frame);
 
-// 59.7275005696Hz
-pub const frame_rate = @intToFloat(f64, std.time.ns_per_s) / 
-    ((@intToFloat(f64, std.time.ns_per_s) / @intToFloat(f64, clock_rate)) * @intToFloat(f64, cycles_per_frame));
-
 const log = std.log.scoped(.Emulation);
 
 const RunKind = enum {
@@ -34,9 +27,9 @@ const RunKind = enum {
 
 pub fn run(kind: RunKind, quit: *Atomic(bool), fps: *FpsAverage, sched: *Scheduler, cpu: *Arm7tdmi, bus: *Bus) void {
     switch (kind) {
-        .Unlimited => runUnsync(quit, sched, cpu, bus),
+        .Unlimited => runUnSync(quit, sched, cpu, bus),
         .Limited => runSync(quit, sched, cpu, bus),
-        .UnlimitedFPS => runUnsyncFps(quit, fps, sched, cpu, bus),
+        .UnlimitedFPS => runUnSyncFps(quit, fps, sched, cpu, bus),
         .LimitedFPS => runSyncFps(quit, fps, sched, cpu, bus),
         .LimitedBusy => runBusyLoop(quit, sched, cpu, bus),
     }
@@ -54,7 +47,7 @@ pub fn runFrame(sched: *Scheduler, cpu: *Arm7tdmi, bus: *Bus) void {
     }
 }
 
-pub fn runUnsync(quit: *Atomic(bool), sched: *Scheduler, cpu: *Arm7tdmi, bus: *Bus) void {
+pub fn runUnSync(quit: *Atomic(bool), sched: *Scheduler, cpu: *Arm7tdmi, bus: *Bus) void {
     log.info("Unsynchronized EmuThread has begun", .{});
     while (!quit.load(.Unordered)) runFrame(sched, cpu, bus);
 }
@@ -76,13 +69,13 @@ pub fn runSync(quit: *Atomic(bool), sched: *Scheduler, cpu: *Arm7tdmi, bus: *Bus
     }
 }
 
-pub fn runUnsyncFps(quit: *Atomic(bool), fps: *FpsAverage, sched: *Scheduler, cpu: *Arm7tdmi, bus: *Bus) void {
+pub fn runUnSyncFps(quit: *Atomic(bool), fps: *FpsAverage, sched: *Scheduler, cpu: *Arm7tdmi, bus: *Bus) void {
     log.info("Unsynchronized EmuThread with FPS Tracking has begun", .{});
     var fps_timer = Timer.start() catch unreachable;
 
     while (!quit.load(.Unordered)) {
         runFrame(sched, cpu, bus);
-        fps.add(fps_timer.lap());
+        fps.add(emuFps(fps_timer.lap()));
     }
 }
 
@@ -100,7 +93,7 @@ pub fn runSyncFps(quit: *Atomic(bool), fps: *FpsAverage, sched: *Scheduler, cpu:
         sleep(&timer, &wake_time);
 
         // Determine FPS
-        fps.add(fps_timer.lap());
+        fps.add(emuFps(fps_timer.lap()));
 
         // Update to the new wake time
         wake_time += frame_period;
@@ -156,3 +149,8 @@ fn sleep(timer: *Timer, wake_time: *u64) void {
 fn spinLoop(timer: *Timer, wake_time: u64) void {
     while (true) if (timer.read() > wake_time) break;
 }
+
+inline fn emuFps(left: u64) u64 {
+    @setRuntimeSafety(false);
+    return @floatToInt(u64, @intToFloat(f64, std.time.ns_per_s) / @intToFloat(f64, left));
+}

src/main.zig

@@ -17,7 +17,6 @@ const window_scale = 3;
 const gba_width = @import("ppu.zig").width;
 const gba_height = @import("ppu.zig").height;
 const framebuf_pitch = @import("ppu.zig").framebuf_pitch;
-const expected_rate = @import("emu.zig").frame_rate;
 
 pub const enable_logging: bool = false;
 const is_binary: bool = false;
@@ -38,9 +37,14 @@ pub fn main() anyerror!void {
     var args = try clap.parse(clap.Help, &params, .{});
     defer args.deinit();
 
-    if (args.flag("--help")) return clap.help(std.io.getStdErr().writer(), &params);
+    if (args.flag("--help")) {
+        return clap.help(std.io.getStdErr().writer(), &params);
+    }
 
-    const maybe_bios: ?[]const u8 = if (args.option("--bios")) |p| p else null;
+    var maybe_bios: ?[]const u8 = null;
+    if (args.option("--bios")) |path| {
+        maybe_bios = path;
+    }
 
     const positionals = args.positionals();
     const stderr = std.io.getStdErr();
@@ -68,19 +72,22 @@ pub fn main() anyerror!void {
     var cpu = Arm7tdmi.init(&scheduler, &bus);
     cpu.fastBoot();
 
-    const log_file: ?File = if (enable_logging) blk: {
-        const file = try std.fs.cwd().createFile(if (is_binary) "zba.bin" else "zba.log", .{});
+    var log_file: ?File = null;
+    if (enable_logging) {
+        const file_name: []const u8 = if (is_binary) "zba.bin" else "zba.log";
+        const file = try std.fs.cwd().createFile(file_name, .{});
         cpu.useLogger(&file, is_binary);
-        break :blk file;
-    } else null;
+
+        log_file = file;
+    }
     defer if (log_file) |file| file.close();
 
     // Init Atomics
     var quit = Atomic(bool).init(false);
-    var emu_rate = FpsAverage.init();
+    var emu_fps = FpsAverage.init();
 
     // Create Emulator Thread
-    const emu_thread = try Thread.spawn(.{}, emu.run, .{ .LimitedFPS, &quit, &emu_rate, &scheduler, &cpu, &bus });
+    const emu_thread = try Thread.spawn(.{}, emu.run, .{ .UnlimitedFPS, &quit, &emu_fps, &scheduler, &cpu, &bus });
     defer emu_thread.join();
 
     // Initialize SDL
@@ -102,7 +109,7 @@ pub fn main() anyerror!void {
     ) orelse sdlPanic();
     defer SDL.SDL_DestroyWindow(window);
 
-    const renderer = SDL.SDL_CreateRenderer(window, -1, SDL.SDL_RENDERER_ACCELERATED | SDL.SDL_RENDERER_PRESENTVSYNC) orelse sdlPanic();
+    var renderer = SDL.SDL_CreateRenderer(window, -1, SDL.SDL_RENDERER_ACCELERATED | SDL.SDL_RENDERER_PRESENTVSYNC) orelse sdlPanic();
     defer SDL.SDL_DestroyRenderer(renderer);
 
     const texture = SDL.SDL_CreateTexture(renderer, SDL.SDL_PIXELFORMAT_RGBA8888, SDL.SDL_TEXTUREACCESS_STREAMING, 240, 160) orelse sdlPanic();
@@ -113,7 +120,7 @@ pub fn main() anyerror!void {
 
     emu_loop: while (true) {
         var event: SDL.SDL_Event = undefined;
-        while (SDL.SDL_PollEvent(&event) != 0) {
+        if (SDL.SDL_PollEvent(&event) != 0) {
             // Pause Emulation Thread during Input Writing
 
             switch (event.type) {
@@ -162,8 +169,8 @@ pub fn main() anyerror!void {
         _ = SDL.SDL_RenderCopy(renderer, texture, null, null);
         SDL.SDL_RenderPresent(renderer);
 
-        const actual = emu_rate.calc();
-        const dyn_title = std.fmt.bufPrint(&dyn_title_buf, "{s} [Emu: {d:0>3.2}fps, {d:0>3.2}%] ", .{ title, actual, actual * 100 / expected_rate }) catch unreachable;
+        const avg = emu_fps.calc();
+        const dyn_title = std.fmt.bufPrint(&dyn_title_buf, "{s} [Emu: {d:0>3}fps, {d:0>3}%] ", .{ title, avg, (avg * 100 / 59) }) catch unreachable;
         SDL.SDL_SetWindowTitle(window, dyn_title.ptr);
     }
 

src/util.zig

@@ -33,8 +33,8 @@ pub const FpsAverage = struct {
         self.sample_count += 1;
     }
 
-    pub fn calc(self: *const Self) f64 {
-        return @intToFloat(f64, std.time.ns_per_s) / (@intToFloat(f64, self.total) / @intToFloat(f64, self.sample_count));
+    pub fn calc(self: *const Self) u64 {
+        return self.total / self.sample_count;
     }
 
     fn reset(self: *Self, sample: u64) void {