chore: move some init code to functions

src/Bus.zig

@@ -84,12 +84,31 @@ pub fn debugRead(self: *const Self, comptime T: type, address: u32) T {
 }
 
 fn readOpenBus(self: *const Self, comptime T: type, address: u32) T {
-    if (self.cpu.?.cpsr.t.read()) {
-        log.err("TODO: {} open bus read in THUMB", .{T});
-        return 0;
-    }
+    const r15 = self.cpu.?.r[15];
+
+    const word = if (self.cpu.?.cpsr.t.read()) blk: {
+        const page = @truncate(u8, r15 >> 24);
+
+        switch (page) {
+            // EWRAM, PALRAM, VRAM, and Game ROM (16-bit)
+            0x02, 0x05, 0x06, 0x08...0x0D => {
+                const halfword = self.debugRead(u16, r15 + 2);
+                break :blk @as(u32, halfword) << 16 | halfword;
+            },
+            // BIOS or OAM (32-bit)
+            0x00, 0x07 => {
+                const offset: u32 = if (address & 3 == 0b00) 2 else 0;
+                break :blk @as(u32, self.debugRead(u16, (r15 + 2) + offset)) << 16 | self.debugRead(u16, r15 + offset);
+            },
+            // IWRAM (16-bit but special)
+            0x03 => {
+                const offset: u32 = if (address & 3 == 0b00) 2 else 0;
+                break :blk @as(u32, self.debugRead(u16, (r15 + 2) - offset)) << 16 | self.debugRead(u16, r15 + offset);
+            },
+            else => unreachable,
+        }
+    } else self.debugRead(u32, r15 + 4);
 
-    const word = self.debugRead(u32, self.cpu.?.r[15] + 4);
     return @truncate(T, rotr(u32, word, 8 * (address & 3)));
 }
 
@@ -152,7 +171,7 @@ pub fn write(self: *Self, comptime T: type, address: u32, value: T) void {
         0x07 => self.ppu.oam.write(T, align_addr, value),
 
         // External Memory (Game Pak)
-        0x08...0x0D => {},
+        0x08...0x0D => {}, // EEPROM
         0x0E...0x0F => {
             const rotate_by = switch (T) {
                 u32 => address & 3,
@@ -163,7 +182,7 @@ pub fn write(self: *Self, comptime T: type, address: u32, value: T) void {
 
             self.pak.backup.write(address, @truncate(u8, rotr(T, value, 8 * rotate_by)));
         },
-        else => undWrite("Tried to write {} 0x{X:} to 0x{X:0>8}", .{ T, value, address }),
+        else => {},
     }
 }
 

src/main.zig

@@ -67,25 +67,12 @@ pub fn main() anyerror!void {
     log.info("Save Path: {s}", .{save_path});
 
     // Initialize SDL
-    const status = SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_EVENTS | SDL.SDL_INIT_AUDIO | SDL.SDL_INIT_GAMECONTROLLER);
+    _ = initSdl2();
     defer SDL.SDL_Quit();
-    if (status < 0) sdlPanic();
 
     // Initialize SDL Audio
-    var have: SDL.SDL_AudioSpec = undefined;
-    var want = std.mem.zeroes(SDL.SDL_AudioSpec);
-    want.freq = 32768;
-    want.format = SDL.AUDIO_S8;
-    want.channels = 2;
-    want.samples = 0x200;
-    want.callback = null;
-
-    const audio_dev = SDL.SDL_OpenAudioDevice(null, 0, &want, &have, 0);
+    const audio_dev = initAudio();
     defer SDL.SDL_CloseAudioDevice(audio_dev);
-    if (audio_dev == 0) sdlPanic();
-
-    // Start Playback on the Audio evice
-    SDL.SDL_PauseAudioDevice(audio_dev, 0);
 
     // Initialize Emulator
     var scheduler = Scheduler.init(alloc);
@@ -113,25 +100,16 @@ pub fn main() anyerror!void {
     const emu_thread = try Thread.spawn(.{}, emu.run, .{ .LimitedFPS, &quit, &emu_rate, &scheduler, &cpu });
     defer emu_thread.join();
 
-    const title = correctTitle(cpu.bus.pak.title);
-
     var title_buf: [0x20]u8 = std.mem.zeroes([0x20]u8);
-    const window_title = try std.fmt.bufPrint(&title_buf, "ZBA | {s}", .{title});
+    const window_title = try std.fmt.bufPrint(&title_buf, "ZBA | {s}", .{correctTitle(cpu.bus.pak.title)});
 
-    var window = SDL.SDL_CreateWindow(
-        window_title.ptr,
-        SDL.SDL_WINDOWPOS_CENTERED,
-        SDL.SDL_WINDOWPOS_CENTERED,
-        gba_width * window_scale,
-        gba_height * window_scale,
-        SDL.SDL_WINDOW_SHOWN,
-    ) orelse sdlPanic();
+    const window = createWindow(window_title, gba_width, gba_height);
     defer SDL.SDL_DestroyWindow(window);
 
-    const renderer = SDL.SDL_CreateRenderer(window, -1, SDL.SDL_RENDERER_ACCELERATED | SDL.SDL_RENDERER_PRESENTVSYNC) orelse sdlPanic();
+    const renderer = createRenderer(window);
     defer SDL.SDL_DestroyRenderer(renderer);
 
-    const texture = SDL.SDL_CreateTexture(renderer, SDL.SDL_PIXELFORMAT_RGBA8888, SDL.SDL_TEXTUREACCESS_STREAMING, 240, 160) orelse sdlPanic();
+    const texture = createTexture(renderer, gba_width, gba_height);
     defer SDL.SDL_DestroyTexture(texture);
 
     // Init FPS Timer
@@ -198,16 +176,16 @@ pub fn main() anyerror!void {
     quit.store(true, .Unordered); // Terminate Emulator Thread
 }
 
-fn sdlPanic() noreturn {
-    const str = @as(?[*:0]const u8, SDL.SDL_GetError()) orelse "unknown error";
-    @panic(std.mem.sliceTo(str, 0));
-}
-
 const CliError = error{
     InsufficientOptions,
     UnneededOptions,
 };
 
+fn sdlPanic() noreturn {
+    const str = @as(?[*:0]const u8, SDL.SDL_GetError()) orelse "unknown error";
+    @panic(std.mem.sliceTo(str, 0));
+}
+
 // FIXME: Superfluous allocations?
 fn setupSavePath(alloc: std.mem.Allocator) !?[]const u8 {
     const save_subpath = try std.fs.path.join(alloc, &[_][]const u8{ "zba", "save" });
@@ -227,3 +205,52 @@ fn setupSavePath(alloc: std.mem.Allocator) !?[]const u8 {
 
     return save_path;
 }
+
+fn initSdl2() c_int {
+    const status = SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_EVENTS | SDL.SDL_INIT_AUDIO | SDL.SDL_INIT_GAMECONTROLLER);
+    if (status < 0) sdlPanic();
+
+    return status;
+}
+
+fn createWindow(title: []u8, width: c_int, height: c_int) *SDL.SDL_Window {
+    return SDL.SDL_CreateWindow(
+        title.ptr,
+        SDL.SDL_WINDOWPOS_CENTERED,
+        SDL.SDL_WINDOWPOS_CENTERED,
+        width * window_scale,
+        height * window_scale,
+        SDL.SDL_WINDOW_SHOWN,
+    ) orelse sdlPanic();
+}
+
+fn createRenderer(window: *SDL.SDL_Window) *SDL.SDL_Renderer {
+    return SDL.SDL_CreateRenderer(window, -1, SDL.SDL_RENDERER_ACCELERATED | SDL.SDL_RENDERER_PRESENTVSYNC) orelse sdlPanic();
+}
+
+fn createTexture(renderer: *SDL.SDL_Renderer, width: c_int, height: c_int) *SDL.SDL_Texture {
+    return SDL.SDL_CreateTexture(
+        renderer,
+        SDL.SDL_PIXELFORMAT_RGBA8888,
+        SDL.SDL_TEXTUREACCESS_STREAMING,
+        width,
+        height,
+    ) orelse sdlPanic();
+}
+
+fn initAudio() SDL.SDL_AudioDeviceID {
+    var have: SDL.SDL_AudioSpec = undefined;
+    var want = std.mem.zeroes(SDL.SDL_AudioSpec);
+    want.freq = 32768;
+    want.format = SDL.AUDIO_S8;
+    want.channels = 2;
+    want.samples = 0x200;
+    want.callback = null;
+
+    const dev = SDL.SDL_OpenAudioDevice(null, 0, &want, &have, 0);
+    if (dev == 0) sdlPanic();
+
+    // Start Playback on the Audio evice
+    SDL.SDL_PauseAudioDevice(dev, 0);
+    return dev;
+}