chore: move imgui-specific code to its own file

src/imgui.zig

@@ -0,0 +1,298 @@
+//! Namespace for dealing with ZBA's immediate-mode GUI
+//! Currently, ZBA uses zgui from https://github.com/michal-z/zig-gamedev
+//! which provides Zig bindings for https://github.com/ocornut/imgui under the hood
+
+const std = @import("std");
+const zgui = @import("zgui");
+const gl = @import("gl");
+const nfd = @import("nfd");
+const config = @import("config.zig");
+const emu = @import("core/emu.zig");
+
+const Gui = @import("platform.zig").Gui;
+const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
+const RingBuffer = @import("util.zig").RingBuffer;
+
+const Allocator = std.mem.Allocator;
+const GLuint = gl.GLuint;
+
+const gba_width = @import("core/ppu.zig").width;
+const gba_height = @import("core/ppu.zig").height;
+
+const log = std.log.scoped(.Imgui);
+
+// TODO: Document how I decided on this value (I forgot 😅)
+const histogram_len = 0x400;
+
+/// Immediate-Mode GUI State
+pub const State = struct {
+    title: [:0]const u8,
+
+    fps_hist: RingBuffer(u32),
+    should_quit: bool = false,
+
+    pub fn init(allocator: Allocator, title: [12]u8) !@This() {
+        const history = try allocator.alloc(u32, histogram_len);
+
+        return .{
+            .title = try allocator.dupeZ(u8, &title),
+            .fps_hist = RingBuffer(u32).init(history),
+        };
+    }
+
+    pub fn deinit(self: *@This(), allocator: Allocator) void {
+        allocator.free(self.title);
+        self.fps_hist.deinit(allocator);
+
+        self.* = undefined;
+    }
+};
+
+pub fn draw(state: *State, tex_id: GLuint, cpu: *const Arm7tdmi) void {
+    const win_scale = config.config().host.win_scale;
+
+    {
+        _ = zgui.beginMainMenuBar();
+        defer zgui.endMainMenuBar();
+
+        if (zgui.beginMenu("File", true)) {
+            defer zgui.endMenu();
+
+            if (zgui.menuItem("Quit", .{})) state.should_quit = true;
+            if (zgui.menuItem("Insert ROM", .{})) blk: {
+                const maybe_path = nfd.openFileDialog("gba", null) catch |e| {
+                    log.err("failed to open file dialog: {?}", .{e});
+                    break :blk;
+                };
+
+                if (maybe_path) |file_path| {
+                    defer nfd.freePath(file_path);
+                    log.info("user chose: \"{s}\"", .{file_path});
+
+                    // emu.loadRom(cpu, file_path);
+                }
+            }
+        }
+
+        if (zgui.beginMenu("Emulation", true)) {
+            defer zgui.endMenu();
+
+            if (zgui.menuItem("Restart", .{})) log.warn("TODO: Restart Emulator", .{});
+        }
+    }
+
+    {
+        const w = @intToFloat(f32, gba_width * win_scale);
+        const h = @intToFloat(f32, gba_height * win_scale);
+
+        _ = zgui.begin(state.title, .{ .flags = .{ .no_resize = true, .always_auto_resize = true } });
+        defer zgui.end();
+
+        zgui.image(@intToPtr(*anyopaque, tex_id), .{ .w = w, .h = h, .uv0 = .{ 0, 1 }, .uv1 = .{ 1, 0 } });
+    }
+
+    {
+        _ = zgui.begin("Information", .{});
+        defer zgui.end();
+
+        for (0..8) |i| {
+            zgui.text("R{}: 0x{X:0>8}", .{ i, cpu.r[i] });
+
+            zgui.sameLine(.{});
+
+            const padding = if (8 + i < 10) " " else "";
+            zgui.text("{s}R{}: 0x{X:0>8}", .{ padding, 8 + i, cpu.r[8 + i] });
+        }
+
+        zgui.separator();
+
+        widgets.psr("CPSR", cpu.cpsr);
+        widgets.psr("SPSR", cpu.spsr);
+
+        zgui.separator();
+
+        widgets.interrupts(" IE", cpu.bus.io.ie);
+        widgets.interrupts("IRQ", cpu.bus.io.irq);
+    }
+
+    {
+        _ = zgui.begin("Performance", .{});
+        defer zgui.end();
+
+        const tmp = blk: {
+            var buf: [0x400]u32 = undefined;
+            const len = state.fps_hist.copy(&buf);
+
+            break :blk .{ buf, len };
+        };
+        const values = tmp[0];
+        const len = tmp[1];
+
+        if (len == values.len) _ = state.fps_hist.pop();
+
+        const sorted = blk: {
+            var buf: @TypeOf(values) = undefined;
+
+            std.mem.copy(u32, buf[0..len], values[0..len]);
+            std.sort.sort(u32, buf[0..len], {}, std.sort.asc(u32));
+
+            break :blk buf;
+        };
+
+        const y_max = 2 * if (len != 0) @intToFloat(f64, sorted[len - 1]) else emu.frame_rate;
+        const x_max = @intToFloat(f64, values.len);
+
+        const y_args = .{ .flags = .{ .no_grid_lines = true } };
+        const x_args = .{ .flags = .{ .no_grid_lines = true, .no_tick_labels = true, .no_tick_marks = true } };
+
+        if (zgui.plot.beginPlot("Emulation FPS", .{ .w = 0.0, .flags = .{ .no_title = true, .no_frame = true } })) {
+            defer zgui.plot.endPlot();
+
+            zgui.plot.setupLegend(.{ .north = true, .east = true }, .{});
+            zgui.plot.setupAxis(.x1, x_args);
+            zgui.plot.setupAxis(.y1, y_args);
+            zgui.plot.setupAxisLimits(.y1, .{ .min = 0.0, .max = y_max, .cond = .always });
+            zgui.plot.setupAxisLimits(.x1, .{ .min = 0.0, .max = x_max, .cond = .always });
+            zgui.plot.setupFinish();
+
+            zgui.plot.plotLineValues("FPS", u32, .{ .v = values[0..len] });
+        }
+
+        const stats: struct { u32, u32, u32 } = blk: {
+            if (len == 0) break :blk .{ 0, 0, 0 };
+
+            const average = average: {
+                var sum: u32 = 0;
+                for (sorted[0..len]) |value| sum += value;
+
+                break :average @intCast(u32, sum / len);
+            };
+            const median = sorted[len / 2];
+            const low = sorted[len / 100]; // 1% Low
+
+            break :blk .{ average, median, low };
+        };
+
+        zgui.text("Average: {:0>3} fps", .{stats[0]});
+        zgui.text(" Median: {:0>3} fps", .{stats[1]});
+        zgui.text(" 1% Low: {:0>3} fps", .{stats[2]});
+    }
+
+    {
+        _ = zgui.begin("Scheduler", .{});
+        defer zgui.end();
+
+        const scheduler = cpu.sched;
+
+        zgui.text("tick: {X:0>16}", .{scheduler.tick});
+        zgui.separator();
+
+        const Event = std.meta.Child(@TypeOf(scheduler.queue.items));
+
+        var items: [20]Event = undefined;
+        const len = scheduler.queue.len;
+
+        std.mem.copy(Event, &items, scheduler.queue.items);
+        std.sort.sort(Event, items[0..len], {}, widgets.eventDesc(Event));
+
+        for (items[0..len]) |event| {
+            zgui.text("{X:0>16} | {?}", .{ event.tick, event.kind });
+        }
+    }
+
+    // {
+    //     zgui.showDemoWindow(null);
+    // }
+}
+
+const widgets = struct {
+    fn interrupts(comptime label: []const u8, int: anytype) void {
+        const h = 15.0;
+        const w = 9.0 * 2 + 3.5;
+        const ww = 9.0 * 3;
+
+        {
+            zgui.text(label ++ ":", .{});
+
+            zgui.sameLine(.{});
+            _ = zgui.selectable("VBL", .{ .w = w, .h = h, .selected = int.vblank.read() });
+
+            zgui.sameLine(.{});
+            _ = zgui.selectable("HBL", .{ .w = w, .h = h, .selected = int.hblank.read() });
+
+            zgui.sameLine(.{});
+            _ = zgui.selectable("VCT", .{ .w = w, .h = h, .selected = int.coincidence.read() });
+
+            {
+                zgui.sameLine(.{});
+                _ = zgui.selectable("TIM0", .{ .w = ww, .h = h, .selected = int.tim0.read() });
+
+                zgui.sameLine(.{});
+                _ = zgui.selectable("TIM1", .{ .w = ww, .h = h, .selected = int.tim1.read() });
+
+                zgui.sameLine(.{});
+                _ = zgui.selectable("TIM2", .{ .w = ww, .h = h, .selected = int.tim2.read() });
+
+                zgui.sameLine(.{});
+                _ = zgui.selectable("TIM3", .{ .w = ww, .h = h, .selected = int.tim3.read() });
+            }
+
+            zgui.sameLine(.{});
+            _ = zgui.selectable("SRL", .{ .w = w, .h = h, .selected = int.serial.read() });
+
+            {
+                zgui.sameLine(.{});
+                _ = zgui.selectable("DMA0", .{ .w = ww, .h = h, .selected = int.dma0.read() });
+
+                zgui.sameLine(.{});
+                _ = zgui.selectable("DMA1", .{ .w = ww, .h = h, .selected = int.dma1.read() });
+
+                zgui.sameLine(.{});
+                _ = zgui.selectable("DMA2", .{ .w = ww, .h = h, .selected = int.dma2.read() });
+
+                zgui.sameLine(.{});
+                _ = zgui.selectable("DMA3", .{ .w = ww, .h = h, .selected = int.dma3.read() });
+            }
+
+            zgui.sameLine(.{});
+            _ = zgui.selectable("KPD", .{ .w = w, .h = h, .selected = int.keypad.read() });
+
+            zgui.sameLine(.{});
+            _ = zgui.selectable("GPK", .{ .w = w, .h = h, .selected = int.game_pak.read() });
+        }
+    }
+
+    fn psr(comptime label: []const u8, register: anytype) void {
+        const Mode = @import("core/cpu.zig").Mode;
+
+        const maybe_mode = std.meta.intToEnum(Mode, register.mode.read()) catch null;
+        const mode = if (maybe_mode) |mode| mode.toString() else "???";
+        const w = 9.0;
+        const h = 15.0;
+
+        zgui.text(label ++ ": 0x{X:0>8}", .{register.raw});
+
+        zgui.sameLine(.{});
+        _ = zgui.selectable("N", .{ .w = w, .h = h, .selected = register.n.read() });
+
+        zgui.sameLine(.{});
+        _ = zgui.selectable("Z", .{ .w = w, .h = h, .selected = register.z.read() });
+
+        zgui.sameLine(.{});
+        _ = zgui.selectable("C", .{ .w = w, .h = h, .selected = register.c.read() });
+
+        zgui.sameLine(.{});
+        _ = zgui.selectable("V", .{ .w = w, .h = h, .selected = register.v.read() });
+
+        zgui.sameLine(.{});
+        zgui.text("{s}", .{mode});
+    }
+
+    fn eventDesc(comptime T: type) fn (void, T, T) bool {
+        return struct {
+            fn inner(_: void, left: T, right: T) bool {
+                return left.tick > right.tick;
+            }
+        }.inner;
+    }
+};

src/platform.zig

@@ -2,10 +2,10 @@ const std = @import("std");
 const SDL = @import("sdl2");
 const gl = @import("gl");
 const zgui = @import("zgui");
-const nfd = @import("nfd");
 
 const emu = @import("core/emu.zig");
 const config = @import("config.zig");
+const imgui = @import("imgui.zig");
 
 const Apu = @import("core/apu.zig").Apu;
 const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
@@ -27,27 +27,12 @@ const height = 720;
 pub const sample_rate = 1 << 15;
 pub const sample_format = SDL.AUDIO_U16;
 
-const default_title = "ZBA";
+const window_title = "ZBA";
 
 pub const Gui = struct {
     const Self = @This();
     const log = std.log.scoped(.Gui);
 
-    const State = struct {
-        fps_hist: RingBuffer(u32),
-        should_quit: bool = false,
-
-        pub fn init(allocator: Allocator) !@This() {
-            const history = try allocator.alloc(u32, 0x400);
-            return .{ .fps_hist = RingBuffer(u32).init(history) };
-        }
-
-        fn deinit(self: *@This(), allocator: Allocator) void {
-            self.fps_hist.deinit(allocator);
-            self.* = undefined;
-        }
-    };
-
     // zig fmt: off
     const vertices: [32]f32 = [_]f32{
         // Positions        // Colours      // Texture Coords
@@ -65,10 +50,9 @@ pub const Gui = struct {
 
     window: *SDL.SDL_Window,
     ctx: SDL_GLContext,
-    title: [:0]const u8,
     audio: Audio,
 
-    state: State,
+    state: imgui.State,
 
     allocator: Allocator,
     program_id: gl.GLuint,
@@ -80,7 +64,7 @@ pub const Gui = struct {
         if (SDL.SDL_GL_SetAttribute(SDL.SDL_GL_CONTEXT_MAJOR_VERSION, 3) < 0) panic();
 
         const window = SDL.SDL_CreateWindow(
-            default_title,
+            window_title,
             SDL.SDL_WINDOWPOS_CENTERED,
             SDL.SDL_WINDOWPOS_CENTERED,
             width,
@@ -102,13 +86,12 @@ pub const Gui = struct {
 
         return Self{
             .window = window,
-            .title = try allocator.dupeZ(u8, &title),
             .ctx = ctx,
             .program_id = try compileShaders(),
             .audio = Audio.init(apu),
 
             .allocator = allocator,
-            .state = try State.init(allocator),
+            .state = try imgui.State.init(allocator, title),
         };
     }
 
@@ -125,7 +108,6 @@ pub const Gui = struct {
         SDL.SDL_DestroyWindow(self.window);
         SDL.SDL_Quit();
 
-        self.allocator.free(self.title);
         self.* = undefined;
     }
 
@@ -260,163 +242,6 @@ pub const Gui = struct {
         return fbo_id;
     }
 
-    fn draw(self: *Self, tex_id: GLuint, cpu: *const Arm7tdmi) void {
-        const win_scale = config.config().host.win_scale;
-
-        {
-            _ = zgui.beginMainMenuBar();
-            defer zgui.endMainMenuBar();
-
-            if (zgui.beginMenu("File", true)) {
-                defer zgui.endMenu();
-
-                if (zgui.menuItem("Quit", .{})) self.state.should_quit = true;
-                if (zgui.menuItem("Insert ROM", .{})) blk: {
-                    const maybe_path = nfd.openFileDialog("gba", null) catch |e| {
-                        log.err("failed to open file dialog: {?}", .{e});
-                        break :blk;
-                    };
-
-                    if (maybe_path) |file_path| {
-                        defer nfd.freePath(file_path);
-                        log.info("user chose: \"{s}\"", .{file_path});
-
-                        // emu.loadRom(cpu, file_path);
-                    }
-                }
-            }
-
-            if (zgui.beginMenu("Emulation", true)) {
-                defer zgui.endMenu();
-
-                if (zgui.menuItem("Restart", .{})) log.warn("TODO: Restart Emulator", .{});
-            }
-        }
-
-        {
-            const w = @intToFloat(f32, gba_width * win_scale);
-            const h = @intToFloat(f32, gba_height * win_scale);
-
-            _ = zgui.begin(self.title, .{ .flags = .{ .no_resize = true, .always_auto_resize = true } });
-            defer zgui.end();
-
-            zgui.image(@intToPtr(*anyopaque, tex_id), .{ .w = w, .h = h, .uv0 = .{ 0, 1 }, .uv1 = .{ 1, 0 } });
-        }
-
-        {
-            _ = zgui.begin("Information", .{});
-            defer zgui.end();
-
-            for (0..8) |i| {
-                zgui.text("R{}: 0x{X:0>8}", .{ i, cpu.r[i] });
-
-                zgui.sameLine(.{});
-
-                const prefix = if (8 + i < 10) " " else "";
-                zgui.text("{s}R{}: 0x{X:0>8}", .{ prefix, 8 + i, cpu.r[8 + i] });
-            }
-
-            zgui.separator();
-
-            widgets.psr("CPSR", cpu.cpsr);
-            widgets.psr("SPSR", cpu.spsr);
-
-            zgui.separator();
-
-            widgets.interrupts(" IE", cpu.bus.io.ie); // space is for padding
-            widgets.interrupts("IRQ", cpu.bus.io.irq);
-        }
-
-        {
-            _ = zgui.begin("Performance", .{});
-            defer zgui.end();
-
-            const tmp = blk: {
-                var buf: [0x400]u32 = undefined;
-                const len = self.state.fps_hist.copy(&buf);
-
-                break :blk .{ buf, len };
-            };
-            const values = tmp[0];
-            const len = tmp[1];
-
-            if (len == values.len) _ = self.state.fps_hist.pop();
-
-            const sorted = blk: {
-                var buf: @TypeOf(values) = undefined;
-
-                std.mem.copy(u32, buf[0..len], values[0..len]);
-                std.sort.sort(u32, buf[0..len], {}, std.sort.asc(u32));
-
-                break :blk buf;
-            };
-
-            const y_max = 2 * if (len != 0) @intToFloat(f64, sorted[len - 1]) else emu.frame_rate;
-            const x_max = @intToFloat(f64, values.len);
-
-            const y_args = .{ .flags = .{ .no_grid_lines = true } };
-            const x_args = .{ .flags = .{ .no_grid_lines = true, .no_tick_labels = true, .no_tick_marks = true } };
-
-            if (zgui.plot.beginPlot("Emulation FPS", .{ .w = 0.0, .flags = .{ .no_title = true, .no_frame = true } })) {
-                defer zgui.plot.endPlot();
-
-                zgui.plot.setupLegend(.{ .north = true, .east = true }, .{});
-                zgui.plot.setupAxis(.x1, x_args);
-                zgui.plot.setupAxis(.y1, y_args);
-                zgui.plot.setupAxisLimits(.y1, .{ .min = 0.0, .max = y_max, .cond = .always });
-                zgui.plot.setupAxisLimits(.x1, .{ .min = 0.0, .max = x_max, .cond = .always });
-                zgui.plot.setupFinish();
-
-                zgui.plot.plotLineValues("FPS", u32, .{ .v = values[0..len] });
-            }
-
-            const stats: struct { u32, u32, u32 } = blk: {
-                if (len == 0) break :blk .{ 0, 0, 0 };
-
-                const average = average: {
-                    var sum: u32 = 0;
-                    for (sorted[0..len]) |value| sum += value;
-
-                    break :average @intCast(u32, sum / len);
-                };
-                const median = sorted[len / 2];
-                const low = sorted[len / 100]; // 1% Low
-
-                break :blk .{ average, median, low };
-            };
-
-            zgui.text("Average: {:0>3} fps", .{stats[0]});
-            zgui.text(" Median: {:0>3} fps", .{stats[1]});
-            zgui.text(" 1% Low: {:0>3} fps", .{stats[2]});
-        }
-
-        {
-            _ = zgui.begin("Scheduler", .{});
-            defer zgui.end();
-
-            const scheduler = cpu.sched;
-
-            zgui.text("tick: {X:0>16}", .{scheduler.tick});
-            zgui.separator();
-
-            const Event = std.meta.Child(@TypeOf(scheduler.queue.items));
-
-            var items: [20]Event = undefined;
-            const len = scheduler.queue.len;
-
-            std.mem.copy(Event, &items, scheduler.queue.items);
-            std.sort.sort(Event, items[0..len], {}, widgets.eventDesc(Event));
-
-            for (items[0..len]) |event| {
-                zgui.text("{X:0>16} | {?}", .{ event.tick, event.kind });
-            }
-        }
-
-        // {
-        //     zgui.showDemoWindow(null);
-        // }
-    }
-
     const RunOptions = struct {
         quit: *std.atomic.Atomic(bool),
         pause: ?*std.atomic.Atomic(bool) = null,
@@ -529,7 +354,7 @@ pub const Gui = struct {
                 gl.clear(gl.COLOR_BUFFER_BIT);
 
                 zgui.backend.newFrame(width, height);
-                self.draw(out_tex, cpu);
+                imgui.draw(&self.state, out_tex, cpu);
                 zgui.backend.draw();
             }
 
@@ -614,95 +439,3 @@ fn panic() noreturn {
     const str = @as(?[*:0]const u8, SDL.SDL_GetError()) orelse "unknown error";
     @panic(std.mem.sliceTo(str, 0));
 }
-
-const widgets = struct {
-    fn interrupts(comptime label: []const u8, int: anytype) void {
-        const h = 15.0;
-        const w = 9.0 * 2 + 3.5;
-        const ww = 9.0 * 3;
-
-        {
-            zgui.text(label ++ ":", .{});
-
-            zgui.sameLine(.{});
-            _ = zgui.selectable("VBL", .{ .w = w, .h = h, .selected = int.vblank.read() });
-
-            zgui.sameLine(.{});
-            _ = zgui.selectable("HBL", .{ .w = w, .h = h, .selected = int.hblank.read() });
-
-            zgui.sameLine(.{});
-            _ = zgui.selectable("VCT", .{ .w = w, .h = h, .selected = int.coincidence.read() });
-
-            {
-                zgui.sameLine(.{});
-                _ = zgui.selectable("TIM0", .{ .w = ww, .h = h, .selected = int.tim0.read() });
-
-                zgui.sameLine(.{});
-                _ = zgui.selectable("TIM1", .{ .w = ww, .h = h, .selected = int.tim1.read() });
-
-                zgui.sameLine(.{});
-                _ = zgui.selectable("TIM2", .{ .w = ww, .h = h, .selected = int.tim2.read() });
-
-                zgui.sameLine(.{});
-                _ = zgui.selectable("TIM3", .{ .w = ww, .h = h, .selected = int.tim3.read() });
-            }
-
-            zgui.sameLine(.{});
-            _ = zgui.selectable("SRL", .{ .w = w, .h = h, .selected = int.serial.read() });
-
-            {
-                zgui.sameLine(.{});
-                _ = zgui.selectable("DMA0", .{ .w = ww, .h = h, .selected = int.dma0.read() });
-
-                zgui.sameLine(.{});
-                _ = zgui.selectable("DMA1", .{ .w = ww, .h = h, .selected = int.dma1.read() });
-
-                zgui.sameLine(.{});
-                _ = zgui.selectable("DMA2", .{ .w = ww, .h = h, .selected = int.dma2.read() });
-
-                zgui.sameLine(.{});
-                _ = zgui.selectable("DMA3", .{ .w = ww, .h = h, .selected = int.dma3.read() });
-            }
-
-            zgui.sameLine(.{});
-            _ = zgui.selectable("KPD", .{ .w = w, .h = h, .selected = int.keypad.read() });
-
-            zgui.sameLine(.{});
-            _ = zgui.selectable("GPK", .{ .w = w, .h = h, .selected = int.game_pak.read() });
-        }
-    }
-
-    fn psr(comptime label: []const u8, register: anytype) void {
-        const Mode = @import("core/cpu.zig").Mode;
-
-        const maybe_mode = std.meta.intToEnum(Mode, register.mode.read()) catch null;
-        const mode = if (maybe_mode) |mode| mode.toString() else "???";
-        const w = 9.0;
-        const h = 15.0;
-
-        zgui.text(label ++ ": 0x{X:0>8}", .{register.raw});
-
-        zgui.sameLine(.{});
-        _ = zgui.selectable("N", .{ .w = w, .h = h, .selected = register.n.read() });
-
-        zgui.sameLine(.{});
-        _ = zgui.selectable("Z", .{ .w = w, .h = h, .selected = register.z.read() });
-
-        zgui.sameLine(.{});
-        _ = zgui.selectable("C", .{ .w = w, .h = h, .selected = register.c.read() });
-
-        zgui.sameLine(.{});
-        _ = zgui.selectable("V", .{ .w = w, .h = h, .selected = register.v.read() });
-
-        zgui.sameLine(.{});
-        zgui.text("{s}", .{mode});
-    }
-
-    fn eventDesc(comptime T: type) fn (void, T, T) bool {
-        return struct {
-            fn inner(_: void, left: T, right: T) bool {
-                return left.tick > right.tick;
-            }
-        }.inner;
-    }
-};