fix(input): make use of atomic rmw intrinsics when handling input

also list dependencies (TODO: add hyperlinks)

build.zig

@@ -8,7 +8,7 @@ const nfd = @import("lib/nfd-zig/build.zig");
 
 pub fn build(b: *std.Build) void {
     // Minimum Zig Version
-    const min_ver = std.SemanticVersion.parse("0.11.0-dev.2168+322ace70f") catch return; // https://github.com/ziglang/zig/commit/322ace70f
+    const min_ver = std.SemanticVersion.parse("0.11.0-dev.2934+1b432072b") catch return; // https://github.com/ziglang/zig/commit/1b432072b
     if (builtin.zig_version.order(min_ver).compare(.lt)) {
         std.log.err("{s}", .{b.fmt("Zig v{} does not meet the minimum version requirement. (Zig v{})", .{ builtin.zig_version, min_ver })});
         std.os.exit(1);
@@ -65,9 +65,9 @@ pub fn build(b: *std.Build) void {
     const zgui_pkg = zgui.package(b, target, optimize, .{ .options = .{ .backend = .sdl2_opengl3, .shared = true } });
     zgui_pkg.link(exe);
 
-    exe.install();
+    b.installArtifact(exe);
 
-    const run_cmd = exe.run();
+    const run_cmd = b.addRunArtifact(exe);
     run_cmd.step.dependOn(b.getInstallStep());
     if (b.args) |args| {
         run_cmd.addArgs(args);

src/core/bus/Ewram.zig

@@ -27,7 +27,7 @@ pub fn write(self: *const Self, comptime T: type, address: usize, value: T) void
 
 pub fn init(allocator: Allocator) !Self {
     const buf = try allocator.alloc(u8, ewram_size);
-    std.mem.set(u8, buf, 0);
+    @memset(buf, 0);
 
     return Self{
         .buf = buf,
@@ -36,7 +36,7 @@ pub fn init(allocator: Allocator) !Self {
 }
 
 pub fn reset(self: *Self) void {
-    std.mem.set(u8, self.buf, 0);
+    @memset(self.buf, 0);
 }
 
 pub fn deinit(self: *Self) void {

src/core/bus/Iwram.zig

@@ -27,7 +27,7 @@ pub fn write(self: *const Self, comptime T: type, address: usize, value: T) void
 
 pub fn init(allocator: Allocator) !Self {
     const buf = try allocator.alloc(u8, iwram_size);
-    std.mem.set(u8, buf, 0);
+    @memset(buf, 0);
 
     return Self{
         .buf = buf,
@@ -36,7 +36,7 @@ pub fn init(allocator: Allocator) !Self {
 }
 
 pub fn reset(self: *Self) void {
-    std.mem.set(u8, self.buf, 0);
+    @memset(self.buf, 0);
 }
 
 pub fn deinit(self: *Self) void {

src/core/bus/backup.zig

@@ -110,7 +110,7 @@ pub const Backup = struct {
         };
 
         const buf = try allocator.alloc(u8, buf_size);
-        std.mem.set(u8, buf, 0xFF);
+        @memset(buf, 0xFF);
 
         var backup = Self{
             .buf = buf,
@@ -163,7 +163,7 @@ pub const Backup = struct {
         switch (self.kind) {
             .Sram, .Flash, .Flash1M => {
                 if (self.buf.len == file_buf.len) {
-                    std.mem.copy(u8, self.buf, file_buf);
+                    @memcpy(self.buf, file_buf);
                     return log.info("Loaded Save from {s}", .{file_path});
                 }
 
@@ -174,7 +174,7 @@ pub const Backup = struct {
                     self.eeprom.kind = if (file_buf.len == 0x200) .Small else .Large;
 
                     self.buf = try allocator.alloc(u8, file_buf.len);
-                    std.mem.copy(u8, self.buf, file_buf);
+                    @memcpy(self.buf, file_buf);
                     return log.info("Loaded Save from {s}", .{file_path});
                 }
 

src/core/bus/backup/Flash.zig

@@ -44,7 +44,7 @@ pub fn handleCommand(self: *Self, buf: []u8, byte: u8) void {
         0xB0 => self.set_bank = true,
         0x80 => self.prep_erase = true,
         0x10 => {
-            std.mem.set(u8, buf, 0xFF);
+            @memset(buf, 0xFF);
             self.prep_erase = false;
         },
         0xA0 => self.prep_write = true,
@@ -61,7 +61,7 @@ pub fn shouldEraseSector(self: *const Self, addr: usize, byte: u8) bool {
 pub fn erase(self: *Self, buf: []u8, sector: usize) void {
     const start = self.address() + (sector & 0xF000);
 
-    std.mem.set(u8, buf[start..][0..0x1000], 0xFF);
+    @memset(buf[start..][0..0x1000], 0xFF);
     self.prep_erase = false;
     self.state = .Ready;
 }

src/core/bus/backup/eeprom.zig

@@ -58,7 +58,9 @@ pub const Eeprom = struct {
                     log.err("Failed to resize EEPROM buf to {} bytes", .{len});
                     std.debug.panic("EEPROM entered irrecoverable state {}", .{e});
                 };
-                std.mem.set(u8, buf.*, 0xFF);
+
+                // FIXME: ptr to a slice?
+                @memset(buf.*, 0xFF);
             }
         }
 

src/core/bus/io.zig

@@ -96,7 +96,7 @@ pub fn read(bus: *const Bus, comptime T: type, address: u32) ?T {
             0x0400_0128 => util.io.read.todo(log, "Read {} from SIOCNT", .{T}),
 
             // Keypad Input
-            0x0400_0130 => bus.io.keyinput.load(.Monotonic).raw,
+            0x0400_0130 => bus.io.keyinput.load(.Monotonic),
 
             // Serial Communication 2
             0x0400_0134 => util.io.read.todo(log, "Read {} from RCNT", .{T}),
@@ -366,7 +366,7 @@ const InterruptEnable = extern union {
 
 /// Read Only
 /// 0 = Pressed, 1 = Released
-const KeyInput = extern union {
+pub const KeyInput = extern union {
     a: Bit(u16, 0),
     b: Bit(u16, 1),
     select: Bit(u16, 2),
@@ -390,18 +390,19 @@ const AtomicKeyInput = struct {
         return .{ .inner = value };
     }
 
-    pub inline fn load(self: *const Self, comptime ordering: Ordering) KeyInput {
+    pub inline fn load(self: *const Self, comptime ordering: Ordering) u16 {
-        return .{ .raw = switch (ordering) {
+        return switch (ordering) {
             .AcqRel, .Release => @compileError("not supported for atomic loads"),
             else => @atomicLoad(u16, &self.inner.raw, ordering),
-        } };
+        };
     }
 
-    pub inline fn store(self: *Self, value: u16, comptime ordering: Ordering) void {
+    pub inline fn fetchOr(self: *Self, value: u16, comptime ordering: Ordering) void {
-        switch (ordering) {
+        _ = @atomicRmw(u16, &self.inner.raw, .Or, value, ordering);
-            .AcqRel, .Acquire => @compileError("not supported for atomic stores"),
-            else => @atomicStore(u16, &self.inner.raw, value, ordering),
     }
+
+    pub inline fn fetchAnd(self: *Self, value: u16, comptime ordering: Ordering) void {
+        _ = @atomicRmw(u16, &self.inner.raw, .And, value, ordering);
     }
 };
 

src/core/cpu.zig

@@ -39,7 +39,7 @@ pub const arm = struct {
     }
 
     fn populate() [0x1000]InstrFn {
-        comptime {
+        return comptime comptime_blk: {
             @setEvalBranchQuota(0xE000);
             var table = [_]InstrFn{und} ** 0x1000;
 
@@ -106,8 +106,8 @@ pub const arm = struct {
                 };
             }
 
-            return table;
+            break :comptime_blk table;
-        }
+        };
     }
 };
 
@@ -135,7 +135,7 @@ pub const thumb = struct {
     }
 
     fn populate() [0x400]InstrFn {
-        comptime {
+        return comptime comptime_blk: {
             @setEvalBranchQuota(5025); // This is exact
             var table = [_]InstrFn{und} ** 0x400;
 
@@ -228,8 +228,8 @@ pub const thumb = struct {
                 };
             }
 
-            return table;
+            break :comptime_blk table;
-        }
+        };
     }
 };
 

src/core/emu.zig

@@ -140,6 +140,10 @@ fn audioSync(audio_sync: bool, stream: *SDL.SDL_AudioStream, is_buffer_full: *bo
     // If Busy is false, there's no need to sync here
     if (!still_full) return;
 
+    // TODO: Refactor!!!!
+    // while (SDL.SDL_AudioStreamAvailable(stream) > sample_size * max_buf_size >> 1)
+    //     std.atomic.spinLoopHint();
+
     while (true) {
         still_full = SDL.SDL_AudioStreamAvailable(stream) > sample_size * max_buf_size >> 1;
         if (!audio_sync or !still_full) break;
@@ -184,7 +188,8 @@ fn sleep(timer: *Timer, wake_time: u64) ?u64 {
 }
 
 fn spinLoop(timer: *Timer, wake_time: u64) void {
-    while (true) if (timer.read() > wake_time) break;
+    while (timer.read() < wake_time)
+        std.atomic.spinLoopHint();
 }
 
 pub const EmuThing = struct {

src/core/ppu.zig

@@ -266,7 +266,7 @@ pub const Ppu = struct {
         sched.push(.Draw, 240 * 4); // Add first PPU Event to Scheduler
 
         const sprites = try allocator.create([128]?Sprite);
-        std.mem.set(?Sprite, sprites, null);
+        @memset(sprites, null);
 
         return Self{
             .vram = try Vram.init(allocator),
@@ -307,7 +307,7 @@ pub const Ppu = struct {
         self.vcount = .{ .raw = 0x0000 };
 
         self.scanline.reset();
-        std.mem.set(?Sprite, self.scanline_sprites, null);
+        @memset(self.scanline_sprites, null);
     }
 
     pub fn deinit(self: *Self) void {
@@ -744,7 +744,7 @@ pub const Ppu = struct {
         // Reset Current Scanline Pixel Buffer and list of fetched sprites
         // in prep for next scanline
         self.scanline.reset();
-        std.mem.set(?Sprite, self.scanline_sprites, null);
+        @memset(self.scanline_sprites, null);
     }
 
     fn getBgr555(self: *Self, maybe_top: Scanline.Pixel, maybe_btm: Scanline.Pixel) u16 {
@@ -1554,7 +1554,7 @@ const Scanline = struct {
 
     fn init(allocator: Allocator) !Self {
         const buf = try allocator.alloc(Pixel, width * 2); // Top & Bottom Scanline
-        std.mem.set(Pixel, buf, .unset);
+        @memset(buf, .unset);
 
         return .{
             // Top & Bototm Layers
@@ -1565,7 +1565,7 @@ const Scanline = struct {
     }
 
     fn reset(self: *Self) void {
-        std.mem.set(Pixel, self.buf, .unset);
+        @memset(self.buf, .unset);
     }
 
     fn deinit(self: *Self) void {

src/core/ppu/Oam.zig

@@ -29,13 +29,13 @@ pub fn write(self: *Self, comptime T: type, address: usize, value: T) void {
 
 pub fn init(allocator: Allocator) !Self {
     const buf = try allocator.alloc(u8, buf_len);
-    std.mem.set(u8, buf, 0);
+    @memset(buf, 0);
 
     return Self{ .buf = buf, .allocator = allocator };
 }
 
 pub fn reset(self: *Self) void {
-    std.mem.set(u8, self.buf, 0);
+    @memset(self.buf, 0);
 }
 
 pub fn deinit(self: *Self) void {

src/core/ppu/Palette.zig

@@ -32,13 +32,13 @@ pub fn write(self: *Self, comptime T: type, address: usize, value: T) void {
 
 pub fn init(allocator: Allocator) !Self {
     const buf = try allocator.alloc(u8, buf_len);
-    std.mem.set(u8, buf, 0);
+    @memset(buf, 0);
 
     return Self{ .buf = buf, .allocator = allocator };
 }
 
 pub fn reset(self: *Self) void {
-    std.mem.set(u8, self.buf, 0);
+    @memset(self.buf, 0);
 }
 
 pub fn deinit(self: *Self) void {

src/core/ppu/Vram.zig

@@ -40,13 +40,13 @@ pub fn write(self: *Self, comptime T: type, dispcnt: io.DisplayControl, address:
 
 pub fn init(allocator: Allocator) !Self {
     const buf = try allocator.alloc(u8, buf_len);
-    std.mem.set(u8, buf, 0);
+    @memset(buf, 0);
 
     return Self{ .buf = buf, .allocator = allocator };
 }
 
 pub fn reset(self: *Self) void {
-    std.mem.set(u8, self.buf, 0);
+    @memset(self.buf, 0);
 }
 
 pub fn deinit(self: *Self) void {

src/imgui.zig

@@ -12,6 +12,7 @@ const emu = @import("core/emu.zig");
 const Gui = @import("platform.zig").Gui;
 const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
 const RingBuffer = @import("zba-util").RingBuffer;
+const Dimensions = @import("platform.zig").Dimensions;
 
 const Allocator = std.mem.Allocator;
 const GLuint = gl.GLuint;
@@ -30,14 +31,34 @@ pub const State = struct {
 
     fps_hist: RingBuffer(u32),
     should_quit: bool = false,
+    emulation: Emulation,
+
+    win_stat: WindowStatus = .{},
+
+    const WindowStatus = struct {
+        show_deps: bool = false,
+        show_regs: bool = false,
+        show_schedule: bool = false,
+        show_perf: bool = false,
+        show_palette: bool = false,
+    };
+
+    const Emulation = union(enum) {
+        Active,
+        Inactive,
+        Transition: enum { Active, Inactive },
+    };
 
     /// if zba is initialized with a ROM already provided, this initializer should be called
     /// with `title_opt` being non-null
     pub fn init(allocator: Allocator, title_opt: ?*const [12]u8) !@This() {
         const history = try allocator.alloc(u32, histogram_len);
 
-        const title: [12:0]u8 = if (title_opt) |t| t.* ++ [_:0]u8{} else "[No Title]\x00\x00".*;
+        return .{
-        return .{ .title = title, .fps_hist = RingBuffer(u32).init(history) };
+            .title = handleTitle(title_opt),
+            .emulation = if (title_opt == null) .Inactive else .Active,
+            .fps_hist = RingBuffer(u32).init(history),
+        };
     }
 
     pub fn deinit(self: *@This(), allocator: Allocator) void {
@@ -46,8 +67,10 @@ pub const State = struct {
     }
 };
 
-pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
+pub fn draw(state: *State, win_dim: Dimensions, tex_id: GLuint, cpu: *Arm7tdmi) bool {
-    const win_scale = config.config().host.win_scale;
+    const scn_scale = config.config().host.win_scale;
+
+    zgui.backend.newFrame(@intToFloat(f32, win_dim.width), @intToFloat(f32, win_dim.height));
 
     {
         _ = zgui.beginMainMenuBar();
@@ -56,7 +79,8 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
         if (zgui.beginMenu("File", true)) {
             defer zgui.endMenu();
 
-            if (zgui.menuItem("Quit", .{})) state.should_quit = true;
+            if (zgui.menuItem("Quit", .{}))
+                state.should_quit = true;
 
             if (zgui.menuItem("Insert ROM", .{})) blk: {
                 const maybe_path = nfd.openFileDialog("gba", null) catch |e| {
@@ -76,22 +100,53 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
                     break :blk;
                 };
 
-                state.title = cpu.bus.pak.title ++ [_:0]u8{};
+                state.title = handleTitle(&cpu.bus.pak.title);
+                state.emulation = .{ .Transition = .Active };
             }
         }
 
         if (zgui.beginMenu("Emulation", true)) {
             defer zgui.endMenu();
 
-            if (zgui.menuItem("Restart", .{})) {
+            if (zgui.menuItem("Registers", .{ .selected = state.win_stat.show_regs }))
+                state.win_stat.show_regs = true;
+
+            if (zgui.menuItem("Palette", .{ .selected = state.win_stat.show_palette }))
+                state.win_stat.show_palette = true;
+
+            if (zgui.menuItem("Schedule", .{ .selected = state.win_stat.show_schedule }))
+                state.win_stat.show_schedule = true;
+
+            if (zgui.menuItem("Paused", .{ .selected = state.emulation == .Inactive })) {
+                state.emulation = switch (state.emulation) {
+                    .Active => .{ .Transition = .Inactive },
+                    .Inactive => .{ .Transition = .Active },
+                    else => state.emulation,
+                };
+            }
+
+            if (zgui.menuItem("Restart", .{}))
                 emu.reset(cpu);
         }
+
+        if (zgui.beginMenu("Stats", true)) {
+            defer zgui.endMenu();
+
+            if (zgui.menuItem("Performance", .{ .selected = state.win_stat.show_perf }))
+                state.win_stat.show_perf = true;
+        }
+
+        if (zgui.beginMenu("Help", true)) {
+            defer zgui.endMenu();
+
+            if (zgui.menuItem("Dependencies", .{ .selected = state.win_stat.show_deps }))
+                state.win_stat.show_deps = true;
         }
     }
 
     {
-        const w = @intToFloat(f32, gba_width * win_scale);
+        const w = @intToFloat(f32, gba_width * scn_scale);
-        const h = @intToFloat(f32, gba_height * win_scale);
+        const h = @intToFloat(f32, gba_height * scn_scale);
 
         const window_title = std.mem.sliceTo(&state.title, 0);
         _ = zgui.begin(window_title, .{ .flags = .{ .no_resize = true, .always_auto_resize = true } });
@@ -100,8 +155,51 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
         zgui.image(@intToPtr(*anyopaque, tex_id), .{ .w = w, .h = h, .uv0 = .{ 0, 1 }, .uv1 = .{ 1, 0 } });
     }
 
+    // TODO: Any other steps to respect the copyright of the libraries I use?
+    if (state.win_stat.show_deps) {
+        _ = zgui.begin("Dependencies", .{ .popen = &state.win_stat.show_deps });
+        defer zgui.end();
+
+        zgui.bulletText("SDL.zig by Felix Queißner", .{});
         {
-        _ = zgui.begin("Information", .{});
+            zgui.indent(.{});
+            defer zgui.unindent(.{});
+
+            zgui.bulletText("SDL by Sam Lantinga", .{});
+        }
+
+        zgui.bulletText("known-folders by ziglibs", .{});
+        zgui.bulletText("nfd-zig by Fabio Arnold", .{});
+        {
+            zgui.indent(.{});
+            defer zgui.unindent(.{});
+
+            zgui.bulletText("nativefiledialog by Michael Labbe", .{});
+        }
+        zgui.bulletText("zba-gdbstub by Rekai Musuka", .{});
+        zgui.bulletText("zba-util by Rekai Musuka", .{});
+        zgui.bulletText("zgui by Michal Ziulek", .{});
+        {
+            zgui.indent(.{});
+            defer zgui.unindent(.{});
+
+            zgui.bulletText("DearImGui by Omar Cornut", .{});
+        }
+        zgui.bulletText("zig-clap by Jimmi Holst Christensen", .{});
+        zgui.bulletText("zig-datetime by Jairus Martin", .{});
+        zgui.bulletText("zig-opengl by Felix Queißner", .{});
+        {
+            zgui.indent(.{});
+            defer zgui.unindent(.{});
+
+            zgui.bulletText("OpenGL-Registry by The Khronos Group", .{});
+        }
+        zgui.bulletText("zig-toml by Aeron Avery", .{});
+        zgui.bulletText("bitfield.zig by Hannes Bredberg and FlorenceOS contributors", .{});
+    }
+
+    if (state.win_stat.show_regs) {
+        _ = zgui.begin("Guest Registers", .{ .popen = &state.win_stat.show_regs });
         defer zgui.end();
 
         for (0..8) |i| {
@@ -124,8 +222,8 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
         widgets.interrupts("IRQ", cpu.bus.io.irq);
     }
 
-    {
+    if (state.win_stat.show_perf) {
-        _ = zgui.begin("Performance", .{});
+        _ = zgui.begin("Performance", .{ .popen = &state.win_stat.show_perf });
         defer zgui.end();
 
         const tmp = blk: {
@@ -142,7 +240,7 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
         const sorted = blk: {
             var buf: @TypeOf(values) = undefined;
 
-            std.mem.copy(u32, buf[0..len], values[0..len]);
+            @memcpy(buf[0..len], values[0..len]);
             std.sort.sort(u32, buf[0..len], {}, std.sort.asc(u32));
 
             break :blk buf;
@@ -187,8 +285,8 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
         zgui.text(" 1% Low: {:0>3} fps", .{stats[2]});
     }
 
-    {
+    if (state.win_stat.show_schedule) {
-        _ = zgui.begin("Scheduler", .{});
+        _ = zgui.begin("Schedule", .{ .popen = &state.win_stat.show_schedule });
         defer zgui.end();
 
         const scheduler = cpu.sched;
@@ -201,7 +299,7 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
         var items: [20]Event = undefined;
         const len = scheduler.queue.len;
 
-        std.mem.copy(Event, &items, scheduler.queue.items);
+        @memcpy(&items, scheduler.queue.items);
         std.sort.sort(Event, items[0..len], {}, widgets.eventDesc(Event));
 
         for (items[0..len]) |event| {
@@ -209,12 +307,61 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
         }
     }
 
-    // {
+    if (state.win_stat.show_palette) {
-    //     zgui.showDemoWindow(null);
+        _ = zgui.begin("Palette", .{ .popen = &state.win_stat.show_palette });
-    // }
+        defer zgui.end();
+
+        widgets.paletteGrid(.Background, cpu);
+
+        zgui.sameLine(.{ .spacing = 20.0 });
+
+        widgets.paletteGrid(.Object, cpu);
+    }
+
+    {
+        zgui.showDemoWindow(null);
+    }
+
+    return true; // request redraw
 }
 
 const widgets = struct {
+    const PaletteKind = enum { Background, Object };
+
+    fn paletteGrid(comptime kind: PaletteKind, cpu: *const Arm7tdmi) void {
+        _ = zgui.beginGroup();
+        defer zgui.endGroup();
+
+        const address: u32 = switch (kind) {
+            .Background => 0x0500_0000,
+            .Object => 0x0500_0200,
+        };
+
+        for (0..0x100) |i| {
+            const offset = @truncate(u32, i);
+            const bgr555 = cpu.bus.dbgRead(u16, address + offset * @sizeOf(u16));
+            widgets.colourSquare(bgr555);
+
+            if ((i + 1) % 0x10 != 0) zgui.sameLine(.{});
+        }
+        zgui.text(@tagName(kind), .{});
+    }
+
+    fn colourSquare(bgr555: u16) void {
+        // FIXME: working with the packed struct enum is currently broken :pensive:
+        const ImguiColorEditFlags_NoInputs: u32 = 1 << 5;
+        const ImguiColorEditFlags_NoPicker: u32 = 1 << 2;
+        const flags = @bitCast(zgui.ColorEditFlags, ImguiColorEditFlags_NoInputs | ImguiColorEditFlags_NoPicker);
+
+        const b = @intToFloat(f32, bgr555 >> 10 & 0x1f);
+        const g = @intToFloat(f32, bgr555 >> 5 & 0x1F);
+        const r = @intToFloat(f32, bgr555 & 0x1F);
+
+        var col = [_]f32{ r / 31.0, g / 31.0, b / 31.0 };
+
+        _ = zgui.colorEdit3("", .{ .col = &col, .flags = flags });
+    }
+
     fn interrupts(comptime label: []const u8, int: anytype) void {
         const h = 15.0;
         const w = 9.0 * 2 + 3.5;
@@ -305,3 +452,13 @@ const widgets = struct {
         }.inner;
     }
 };
+
+fn handleTitle(title_opt: ?*const [12]u8) [12:0]u8 {
+    if (title_opt == null) return "[N/A Title]\x00".*; // No ROM present
+    const title = title_opt.?;
+
+    // ROM Title is an empty string (ImGui hates these)
+    if (title[0] == '\x00') return "[No Title]\x00\x00".*;
+
+    return title.* ++ [_:0]u8{};
+}

src/main.zig

@@ -31,7 +31,7 @@ const params = clap.parseParamsComptime(
 pub fn main() void {
     // Main Allocator for ZBA
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
-    defer std.debug.assert(!gpa.deinit());
+    defer std.debug.assert(gpa.deinit() == .ok);
 
     const allocator = gpa.allocator();
 
@@ -86,7 +86,7 @@ pub fn main() void {
     bus.init(allocator, &scheduler, &cpu, paths) catch |e| exitln("failed to init zba bus: {}", .{e});
     defer bus.deinit();
 
-    if (config.config().guest.skip_bios or result.args.skip or paths.bios == null) {
+    if (config.config().guest.skip_bios or result.args.skip != 0 or paths.bios == null) {
         cpu.fastBoot();
     }
 
@@ -101,7 +101,7 @@ pub fn main() void {
     var items: [0x100]u8 = undefined;
     var channel = TwoWayChannel.init(&items);
 
-    if (result.args.gdb) {
+    if (result.args.gdb != 0) {
         const Server = @import("gdbstub").Server;
         const EmuThing = @import("core/emu.zig").EmuThing;
 
@@ -119,7 +119,7 @@ pub fn main() void {
         const thread = std.Thread.spawn(.{}, Server.run, .{ &server, allocator, &quit }) catch |e| exitln("gdb server thread crashed: {}", .{e});
         defer thread.join();
 
-        gui.run(.{
+        gui.run(.Debug, .{
             .cpu = &cpu,
             .scheduler = &scheduler,
             .channel = &channel,
@@ -127,10 +127,14 @@ pub fn main() void {
     } else {
         var tracker = FpsTracker.init();
 
+        // emu should start paused if there's no ROM to run
+        if (paths.rom == null)
+            channel.emu.push(.Pause);
+
         const thread = std.Thread.spawn(.{}, emu.run, .{ &cpu, &scheduler, &tracker, &channel }) catch |e| exitln("emu thread panicked: {}", .{e});
         defer thread.join();
 
-        gui.run(.{
+        gui.run(.Standard, .{
             .cpu = &cpu,
             .scheduler = &scheduler,
             .channel = &channel,

src/platform.zig

@@ -12,6 +12,7 @@ const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
 const Scheduler = @import("core/scheduler.zig").Scheduler;
 const FpsTracker = @import("util.zig").FpsTracker;
 const TwoWayChannel = @import("zba-util").TwoWayChannel;
+const KeyInput = @import("core/bus/io.zig").KeyInput;
 
 const gba_width = @import("core/ppu.zig").width;
 const gba_height = @import("core/ppu.zig").height;
@@ -21,8 +22,8 @@ const GLsizei = gl.GLsizei;
 const SDL_GLContext = *anyopaque;
 const Allocator = std.mem.Allocator;
 
-const width = 1280;
+pub const Dimensions = struct { width: u32, height: u32 };
-const height = 720;
+const default_dim: Dimensions = .{ .width = 1280, .height = 720 };
 
 pub const sample_rate = 1 << 15;
 pub const sample_format = SDL.AUDIO_U16;
@@ -33,29 +34,12 @@ pub const Gui = struct {
     const Self = @This();
     const log = std.log.scoped(.Gui);
 
-    // zig fmt: off
-    const vertices: [32]f32 = [_]f32{
-        // Positions        // Colours      // Texture Coords
-         1.0, -1.0, 0.0,    1.0, 0.0, 0.0,  1.0, 1.0, // Top Right
-         1.0,  1.0, 0.0,    0.0, 1.0, 0.0,  1.0, 0.0, // Bottom Right
-        -1.0,  1.0, 0.0,    0.0, 0.0, 1.0,  0.0, 0.0, // Bottom Left
-        -1.0, -1.0, 0.0,    1.0, 1.0, 0.0,  0.0, 1.0, // Top Left
-    };
-
-    const indices: [6]u32 = [_]u32{
-        0, 1, 3, // First Triangle
-        1, 2, 3, // Second Triangle
-    };
-    // zig fmt: on
-
     window: *SDL.SDL_Window,
     ctx: SDL_GLContext,
     audio: Audio,
 
     state: imgui.State,
-
     allocator: Allocator,
-    program_id: gl.GLuint,
 
     pub fn init(allocator: Allocator, apu: *Apu, title_opt: ?*const [12]u8) !Self {
         if (SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_EVENTS | SDL.SDL_INIT_AUDIO) < 0) panic();
@@ -67,9 +51,9 @@ pub const Gui = struct {
             window_title,
             SDL.SDL_WINDOWPOS_CENTERED,
             SDL.SDL_WINDOWPOS_CENTERED,
-            width,
+            default_dim.width,
-            height,
+            default_dim.height,
-            SDL.SDL_WINDOW_OPENGL | SDL.SDL_WINDOW_SHOWN,
+            SDL.SDL_WINDOW_OPENGL | SDL.SDL_WINDOW_SHOWN | SDL.SDL_WINDOW_RESIZABLE,
         ) orelse panic();
 
         const ctx = SDL.SDL_GL_CreateContext(window) orelse panic();
@@ -87,7 +71,6 @@ pub const Gui = struct {
         return Self{
             .window = window,
             .ctx = ctx,
-            .program_id = try compileShaders(),
             .audio = Audio.init(apu),
 
             .allocator = allocator,
@@ -103,7 +86,6 @@ pub const Gui = struct {
         zgui.plot.deinit();
         zgui.deinit();
 
-        gl.deleteProgram(self.program_id);
         SDL.SDL_GL_DeleteContext(self.ctx);
         SDL.SDL_DestroyWindow(self.window);
         SDL.SDL_Quit();
@@ -111,137 +93,6 @@ pub const Gui = struct {
         self.* = undefined;
     }
 
-    fn drawGbaTexture(self: *const Self, obj_ids: struct { GLuint, GLuint, GLuint }, tex_id: GLuint, buf: []const u8) void {
-        gl.bindTexture(gl.TEXTURE_2D, tex_id);
-        defer gl.bindTexture(gl.TEXTURE_2D, 0);
-
-        gl.texSubImage2D(gl.TEXTURE_2D, 0, 0, 0, gba_width, gba_height, gl.RGBA, gl.UNSIGNED_INT_8_8_8_8, buf.ptr);
-
-        // Bind VAO, EBO. VBO not bound
-        gl.bindVertexArray(obj_ids[0]); // VAO
-        defer gl.bindVertexArray(0);
-
-        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, obj_ids[2]); // EBO
-        defer gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, 0);
-
-        // Use compiled frag + vertex shader
-        gl.useProgram(self.program_id);
-        defer gl.useProgram(0);
-
-        gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_INT, null);
-    }
-
-    fn compileShaders() !GLuint {
-        const vert_shader = @embedFile("shader/pixelbuf.vert");
-        const frag_shader = @embedFile("shader/pixelbuf.frag");
-
-        const vs = gl.createShader(gl.VERTEX_SHADER);
-        defer gl.deleteShader(vs);
-
-        gl.shaderSource(vs, 1, &[_][*c]const u8{vert_shader}, 0);
-        gl.compileShader(vs);
-
-        if (!shader.didCompile(vs)) return error.VertexCompileError;
-
-        const fs = gl.createShader(gl.FRAGMENT_SHADER);
-        defer gl.deleteShader(fs);
-
-        gl.shaderSource(fs, 1, &[_][*c]const u8{frag_shader}, 0);
-        gl.compileShader(fs);
-
-        if (!shader.didCompile(fs)) return error.FragmentCompileError;
-
-        const program = gl.createProgram();
-        gl.attachShader(program, vs);
-        gl.attachShader(program, fs);
-        gl.linkProgram(program);
-
-        return program;
-    }
-
-    // Returns the VAO ID since it's used in run()
-    fn genBufferObjects() struct { GLuint, GLuint, GLuint } {
-        var vao_id: GLuint = undefined;
-        var vbo_id: GLuint = undefined;
-        var ebo_id: GLuint = undefined;
-
-        gl.genVertexArrays(1, &vao_id);
-        gl.genBuffers(1, &vbo_id);
-        gl.genBuffers(1, &ebo_id);
-
-        gl.bindVertexArray(vao_id);
-        defer gl.bindVertexArray(0);
-
-        gl.bindBuffer(gl.ARRAY_BUFFER, vbo_id);
-        defer gl.bindBuffer(gl.ARRAY_BUFFER, 0);
-
-        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ebo_id);
-        defer gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, 0);
-
-        gl.bufferData(gl.ARRAY_BUFFER, @sizeOf(@TypeOf(vertices)), &vertices, gl.STATIC_DRAW);
-        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, @sizeOf(@TypeOf(indices)), &indices, gl.STATIC_DRAW);
-
-        // Position
-        gl.vertexAttribPointer(0, 3, gl.FLOAT, gl.FALSE, 8 * @sizeOf(f32), null); // lmao
-        gl.enableVertexAttribArray(0);
-        // Colour
-        gl.vertexAttribPointer(1, 3, gl.FLOAT, gl.FALSE, 8 * @sizeOf(f32), @intToPtr(?*anyopaque, (3 * @sizeOf(f32))));
-        gl.enableVertexAttribArray(1);
-        // Texture Coord
-        gl.vertexAttribPointer(2, 2, gl.FLOAT, gl.FALSE, 8 * @sizeOf(f32), @intToPtr(?*anyopaque, (6 * @sizeOf(f32))));
-        gl.enableVertexAttribArray(2);
-
-        return .{ vao_id, vbo_id, ebo_id };
-    }
-
-    fn genGbaTexture(buf: []const u8) GLuint {
-        var tex_id: GLuint = undefined;
-        gl.genTextures(1, &tex_id);
-
-        gl.bindTexture(gl.TEXTURE_2D, tex_id);
-        defer gl.bindTexture(gl.TEXTURE_2D, 0);
-
-        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
-        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
-
-        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gba_width, gba_height, 0, gl.RGBA, gl.UNSIGNED_INT_8_8_8_8, buf.ptr);
-
-        return tex_id;
-    }
-
-    fn genOutTexture() GLuint {
-        var tex_id: GLuint = undefined;
-        gl.genTextures(1, &tex_id);
-
-        gl.bindTexture(gl.TEXTURE_2D, tex_id);
-        defer gl.bindTexture(gl.TEXTURE_2D, 0);
-
-        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
-        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
-
-        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gba_width, gba_height, 0, gl.RGBA, gl.UNSIGNED_INT_8_8_8_8, null);
-
-        return tex_id;
-    }
-
-    fn genFrameBufObject(tex_id: c_uint) !GLuint {
-        var fbo_id: GLuint = undefined;
-        gl.genFramebuffers(1, &fbo_id);
-
-        gl.bindFramebuffer(gl.FRAMEBUFFER, fbo_id);
-        defer gl.bindFramebuffer(gl.FRAMEBUFFER, 0);
-
-        gl.framebufferTexture(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, tex_id, 0);
-
-        const draw_buffers: [1]GLuint = .{gl.COLOR_ATTACHMENT0};
-        gl.drawBuffers(1, &draw_buffers);
-
-        if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE)
-            return error.FrameBufferObejctInitFailed;
-
-        return fbo_id;
-    }
-
     const RunOptions = struct {
         channel: *TwoWayChannel,
         tracker: ?*FpsTracker = null,
@@ -249,29 +100,30 @@ pub const Gui = struct {
         scheduler: *Scheduler,
     };
 
-    pub fn run(self: *Self, opt: RunOptions) !void {
+    const RunMode = enum { Standard, Debug };
+
+    pub fn run(self: *Self, comptime mode: RunMode, opt: RunOptions) !void {
         const cpu = opt.cpu;
         const tracker = opt.tracker;
         const channel = opt.channel;
 
-        const obj_ids = Self.genBufferObjects();
+        const objects = opengl_impl.createObjects();
-        defer gl.deleteBuffers(3, @as(*const [3]c_uint, &obj_ids));
+        defer gl.deleteBuffers(3, @as(*const [3]GLuint, &.{ objects.vao, objects.vbo, objects.ebo }));
 
-        const emu_tex = Self.genGbaTexture(cpu.bus.ppu.framebuf.get(.Renderer));
+        const emu_tex = opengl_impl.createScreenTexture(cpu.bus.ppu.framebuf.get(.Renderer));
-        const out_tex = Self.genOutTexture();
+        const out_tex = opengl_impl.createOutputTexture();
-        defer gl.deleteTextures(2, &[_]c_uint{ emu_tex, out_tex });
+        defer gl.deleteTextures(2, &[_]GLuint{ emu_tex, out_tex });
 
-        const fbo_id = try Self.genFrameBufObject(out_tex);
+        const fbo_id = try opengl_impl.createFrameBuffer(out_tex);
         defer gl.deleteFramebuffers(1, &fbo_id);
 
-        emu_loop: while (true) {
+        // TODO: Support dynamically switching shaders?
-            // `quit` from RunOptions may be modified by the GDBSTUB thread,
+        const prog_id = try opengl_impl.compileShaders();
-            // so we want to recognize that it may change to `true` and exit the GUI thread
+        defer gl.deleteProgram(prog_id);
-            if (channel.gui.pop()) |event| switch (event) {
-                .Quit => break :emu_loop,
-                .Paused => @panic("TODO: We want to peek (and then pop if it's .Quit), not always pop"),
-            };
 
+        var win_dim: Dimensions = default_dim;
+
+        emu_loop: while (true) {
             // Outside of `SDL.SDL_QUIT` below, the DearImgui UI might signal that the program
             // should exit, in which case we should also handle this
             if (self.state.should_quit) break :emu_loop;
@@ -283,28 +135,9 @@ pub const Gui = struct {
                 switch (event.type) {
                     SDL.SDL_QUIT => break :emu_loop,
                     SDL.SDL_KEYDOWN => {
+                        // TODO: Make use of compare_and_xor?
                         const key_code = event.key.keysym.sym;
-                        var keyinput = cpu.bus.io.keyinput.load(.Monotonic);
+                        var keyinput: KeyInput = .{ .raw = 0x0000 };
-
-                        switch (key_code) {
-                            SDL.SDLK_UP => keyinput.up.unset(),
-                            SDL.SDLK_DOWN => keyinput.down.unset(),
-                            SDL.SDLK_LEFT => keyinput.left.unset(),
-                            SDL.SDLK_RIGHT => keyinput.right.unset(),
-                            SDL.SDLK_x => keyinput.a.unset(),
-                            SDL.SDLK_z => keyinput.b.unset(),
-                            SDL.SDLK_a => keyinput.shoulder_l.unset(),
-                            SDL.SDLK_s => keyinput.shoulder_r.unset(),
-                            SDL.SDLK_RETURN => keyinput.start.unset(),
-                            SDL.SDLK_RSHIFT => keyinput.select.unset(),
-                            else => {},
-                        }
-
-                        cpu.bus.io.keyinput.store(keyinput.raw, .Monotonic);
-                    },
-                    SDL.SDL_KEYUP => {
-                        const key_code = event.key.keysym.sym;
-                        var keyinput = cpu.bus.io.keyinput.load(.Monotonic);
 
                         switch (key_code) {
                             SDL.SDLK_UP => keyinput.up.set(),
@@ -320,21 +153,90 @@ pub const Gui = struct {
                             else => {},
                         }
 
-                        cpu.bus.io.keyinput.store(keyinput.raw, .Monotonic);
+                        cpu.bus.io.keyinput.fetchAnd(~keyinput.raw, .Monotonic);
+                    },
+                    SDL.SDL_KEYUP => {
+                        // TODO: Make use of compare_and_xor?
+                        const key_code = event.key.keysym.sym;
+                        var keyinput: KeyInput = .{ .raw = 0x0000 };
+
+                        switch (key_code) {
+                            SDL.SDLK_UP => keyinput.up.set(),
+                            SDL.SDLK_DOWN => keyinput.down.set(),
+                            SDL.SDLK_LEFT => keyinput.left.set(),
+                            SDL.SDLK_RIGHT => keyinput.right.set(),
+                            SDL.SDLK_x => keyinput.a.set(),
+                            SDL.SDLK_z => keyinput.b.set(),
+                            SDL.SDLK_a => keyinput.shoulder_l.set(),
+                            SDL.SDLK_s => keyinput.shoulder_r.set(),
+                            SDL.SDLK_RETURN => keyinput.start.set(),
+                            SDL.SDLK_RSHIFT => keyinput.select.set(),
+                            else => {},
+                        }
+
+                        cpu.bus.io.keyinput.fetchOr(keyinput.raw, .Monotonic);
+                    },
+                    SDL.SDL_WINDOWEVENT => {
+                        if (event.window.event == SDL.SDL_WINDOWEVENT_RESIZED) {
+                            log.debug("window resized to: {}x{}", .{ event.window.data1, event.window.data2 });
+
+                            win_dim.width = @intCast(u32, event.window.data1);
+                            win_dim.height = @intCast(u32, event.window.data2);
+                        }
                     },
                     else => {},
                 }
             }
 
-            {
+            var zgui_redraw: bool = false;
-                channel.emu.push(.Pause);
-                defer channel.emu.push(.Resume);
 
-                // Spin Loop until we know that the emu is paused
+            switch (self.state.emulation) {
-                wait: while (true) switch (channel.gui.pop() orelse continue) {
+                .Transition => |inner| switch (inner) {
-                    .Paused => break :wait,
+                    .Active => {
-                    else => |any| std.debug.panic("[Gui/Channel]: Unhandled Event: {}", .{any}),
+                        _ = channel.gui.pop();
-                };
+
+                        channel.emu.push(.Resume);
+                        self.state.emulation = .Active;
+                    },
+                    .Inactive => {
+                        // Assert that double pausing is impossible
+                        if (channel.gui.peek()) |value|
+                            std.debug.assert(value != .Paused);
+
+                        channel.emu.push(.Pause);
+                        self.state.emulation = .Inactive;
+                    },
+                },
+                .Active => skip_draw: {
+                    const is_std = mode == .Standard;
+
+                    if (is_std) channel.emu.push(.Pause);
+                    defer if (is_std) channel.emu.push(.Resume);
+
+                    switch (mode) {
+                        .Standard => blk: {
+                            const limit = 15; // TODO: What should this be?
+
+                            // TODO: learn more about std.atomic.spinLoopHint();
+                            for (0..limit) |_| {
+                                const message = channel.gui.pop() orelse continue;
+
+                                switch (message) {
+                                    .Paused => break :blk,
+                                    .Quit => unreachable,
+                                }
+                            }
+
+                            log.info("timed out waiting for emu thread to pause (limit: {})", .{limit});
+                            break :skip_draw;
+                        },
+                        .Debug => blk: {
+                            switch (channel.gui.pop() orelse break :blk) {
+                                .Paused => unreachable, // only in standard mode
+                                .Quit => break :emu_loop, // FIXME: gdb side of emu is seriously out-of-date...
+                            }
+                        },
+                    }
 
                     // Add FPS count to the histogram
                     if (tracker) |t| self.state.fps_hist.push(t.value()) catch {};
@@ -346,17 +248,21 @@ pub const Gui = struct {
 
                         const buf = cpu.bus.ppu.framebuf.get(.Renderer);
                         gl.viewport(0, 0, gba_width, gba_height);
-                    self.drawGbaTexture(obj_ids, emu_tex, buf);
+                        opengl_impl.drawScreenTexture(emu_tex, prog_id, objects, buf);
                     }
 
+                    zgui_redraw = imgui.draw(&self.state, win_dim, out_tex, cpu);
+                },
+                .Inactive => zgui_redraw = imgui.draw(&self.state, win_dim, out_tex, cpu),
+            }
+
+            if (zgui_redraw) {
                 // Background Colour
                 const size = zgui.io.getDisplaySize();
-                gl.viewport(0, 0, @floatToInt(c_int, size[0]), @floatToInt(c_int, size[1]));
+                gl.viewport(0, 0, @floatToInt(GLsizei, size[0]), @floatToInt(GLsizei, size[1]));
                 gl.clearColor(0, 0, 0, 1.0);
                 gl.clear(gl.COLOR_BUFFER_BIT);
 
-                zgui.backend.newFrame(width, height);
-                imgui.draw(&self.state, out_tex, cpu);
                 zgui.backend.draw();
             }
 
@@ -415,7 +321,161 @@ const Audio = struct {
     }
 };
 
-const shader = struct {
+fn panic() noreturn {
+    const str = @as(?[*:0]const u8, SDL.SDL_GetError()) orelse "unknown error";
+    @panic(std.mem.sliceTo(str, 0));
+}
+
+const opengl_impl = struct {
+    // zig fmt: off
+    const vertices: [32]f32 = [_]f32{
+        // Positions        // Colours      // Texture Coords
+         1.0, -1.0, 0.0,    1.0, 0.0, 0.0,  1.0, 1.0, // Top Right
+         1.0,  1.0, 0.0,    0.0, 1.0, 0.0,  1.0, 0.0, // Bottom Right
+        -1.0,  1.0, 0.0,    0.0, 0.0, 1.0,  0.0, 0.0, // Bottom Left
+        -1.0, -1.0, 0.0,    1.0, 1.0, 0.0,  0.0, 1.0, // Top Left
+    };
+
+    const indices: [6]u32 = [_]u32{
+        0, 1, 3, // First Triangle
+        1, 2, 3, // Second Triangle
+    };
+    // zig fmt: on
+
+    const Objects = struct { vao: GLuint, vbo: GLuint, ebo: GLuint };
+
+    fn drawScreenTexture(tex_id: GLuint, prog_id: GLuint, ids: Objects, buf: []const u8) void {
+        gl.bindTexture(gl.TEXTURE_2D, tex_id);
+        defer gl.bindTexture(gl.TEXTURE_2D, 0);
+
+        gl.texSubImage2D(gl.TEXTURE_2D, 0, 0, 0, gba_width, gba_height, gl.RGBA, gl.UNSIGNED_INT_8_8_8_8, buf.ptr);
+
+        // Bind VAO, EBO. VBO not bound
+        gl.bindVertexArray(ids.vao); // VAO
+        defer gl.bindVertexArray(0);
+
+        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ids.ebo); // EBO
+        defer gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, 0);
+
+        // Use compiled frag + vertex shader
+        gl.useProgram(prog_id);
+        defer gl.useProgram(0);
+
+        gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_INT, null);
+    }
+
+    fn compileShaders() !GLuint {
+        const vert_shader = @embedFile("shader/pixelbuf.vert");
+        const frag_shader = @embedFile("shader/pixelbuf.frag");
+
+        const vs = gl.createShader(gl.VERTEX_SHADER);
+        defer gl.deleteShader(vs);
+
+        gl.shaderSource(vs, 1, &[_][*c]const u8{vert_shader}, 0);
+        gl.compileShader(vs);
+
+        if (!shader.didCompile(vs)) return error.VertexCompileError;
+
+        const fs = gl.createShader(gl.FRAGMENT_SHADER);
+        defer gl.deleteShader(fs);
+
+        gl.shaderSource(fs, 1, &[_][*c]const u8{frag_shader}, 0);
+        gl.compileShader(fs);
+
+        if (!shader.didCompile(fs)) return error.FragmentCompileError;
+
+        const program = gl.createProgram();
+        gl.attachShader(program, vs);
+        gl.attachShader(program, fs);
+        gl.linkProgram(program);
+
+        return program;
+    }
+
+    // Returns the VAO ID since it's used in run()
+    fn createObjects() Objects {
+        var vao_id: GLuint = undefined;
+        var vbo_id: GLuint = undefined;
+        var ebo_id: GLuint = undefined;
+
+        gl.genVertexArrays(1, &vao_id);
+        gl.genBuffers(1, &vbo_id);
+        gl.genBuffers(1, &ebo_id);
+
+        gl.bindVertexArray(vao_id);
+        defer gl.bindVertexArray(0);
+
+        gl.bindBuffer(gl.ARRAY_BUFFER, vbo_id);
+        defer gl.bindBuffer(gl.ARRAY_BUFFER, 0);
+
+        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ebo_id);
+        defer gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, 0);
+
+        gl.bufferData(gl.ARRAY_BUFFER, @sizeOf(@TypeOf(vertices)), &vertices, gl.STATIC_DRAW);
+        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, @sizeOf(@TypeOf(indices)), &indices, gl.STATIC_DRAW);
+
+        // Position
+        gl.vertexAttribPointer(0, 3, gl.FLOAT, gl.FALSE, 8 * @sizeOf(f32), null); // lmao
+        gl.enableVertexAttribArray(0);
+        // Colour
+        gl.vertexAttribPointer(1, 3, gl.FLOAT, gl.FALSE, 8 * @sizeOf(f32), @intToPtr(?*anyopaque, (3 * @sizeOf(f32))));
+        gl.enableVertexAttribArray(1);
+        // Texture Coord
+        gl.vertexAttribPointer(2, 2, gl.FLOAT, gl.FALSE, 8 * @sizeOf(f32), @intToPtr(?*anyopaque, (6 * @sizeOf(f32))));
+        gl.enableVertexAttribArray(2);
+
+        return .{ .vao = vao_id, .vbo = vbo_id, .ebo = ebo_id };
+    }
+
+    fn createScreenTexture(buf: []const u8) GLuint {
+        var tex_id: GLuint = undefined;
+        gl.genTextures(1, &tex_id);
+
+        gl.bindTexture(gl.TEXTURE_2D, tex_id);
+        defer gl.bindTexture(gl.TEXTURE_2D, 0);
+
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
+
+        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gba_width, gba_height, 0, gl.RGBA, gl.UNSIGNED_INT_8_8_8_8, buf.ptr);
+
+        return tex_id;
+    }
+
+    fn createOutputTexture() GLuint {
+        var tex_id: GLuint = undefined;
+        gl.genTextures(1, &tex_id);
+
+        gl.bindTexture(gl.TEXTURE_2D, tex_id);
+        defer gl.bindTexture(gl.TEXTURE_2D, 0);
+
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
+
+        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gba_width, gba_height, 0, gl.RGBA, gl.UNSIGNED_INT_8_8_8_8, null);
+
+        return tex_id;
+    }
+
+    fn createFrameBuffer(tex_id: GLuint) !GLuint {
+        var fbo_id: GLuint = undefined;
+        gl.genFramebuffers(1, &fbo_id);
+
+        gl.bindFramebuffer(gl.FRAMEBUFFER, fbo_id);
+        defer gl.bindFramebuffer(gl.FRAMEBUFFER, 0);
+
+        gl.framebufferTexture(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, tex_id, 0);
+
+        const draw_buffers: [1]GLuint = .{gl.COLOR_ATTACHMENT0};
+        gl.drawBuffers(1, &draw_buffers);
+
+        if (gl.checkFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE)
+            return error.FrameBufferObejctInitFailed;
+
+        return fbo_id;
+    }
+
+    const shader = struct {
         const Kind = enum { vertex, fragment };
         const log = std.log.scoped(.Shader);
 
@@ -435,9 +495,5 @@ const shader = struct {
             gl.getShaderInfoLog(id, buf_len, 0, &error_msg);
             log.err("{s}", .{std.mem.sliceTo(&error_msg, 0)});
         }
+    };
 };
-
-fn panic() noreturn {
-    const str = @as(?[*:0]const u8, SDL.SDL_GetError()) orelse "unknown error";
-    @panic(std.mem.sliceTo(str, 0));
-}

src/util.zig

@@ -260,7 +260,7 @@ pub const FrameBuffer = struct {
 
     pub fn init(allocator: Allocator, comptime len: comptime_int) !Self {
         const buf = try allocator.alloc(u8, len * 2);
-        std.mem.set(u8, buf, 0);
+        @memset(buf, 0);
 
         return .{
             // Front and Back Framebuffers
@@ -272,7 +272,7 @@ pub const FrameBuffer = struct {
     }
 
     pub fn reset(self: *Self) void {
-        std.mem.set(u8, self.buf, 0);
+        @memset(self.buf, 0);
         self.current = 0;
     }