chore(ui): rewrite channel implementation

lib/zba-util

@@ -1 +1 @@
-Subproject commit 72349459ec29ee2d910a3dd3274be00254a7acd4
+Subproject commit 77d11c9903d7f4a3a31ef59fc954421d7dfa0eb1

src/core/emu.zig

@@ -5,7 +5,9 @@ const config = @import("../config.zig");
 const Scheduler = @import("scheduler.zig").Scheduler;
 const Arm7tdmi = @import("cpu.zig").Arm7tdmi;
 const Tracker = @import("../util.zig").FpsTracker;
-const TwoWayChannel = @import("zba-util").TwoWayChannel;
+const Channel = @import("zba-util").Channel(Message, 0x100);
+
+pub const Message = enum { Pause, Resume, Quit };
 
 const Timer = std.time.Timer;
 
@@ -35,18 +37,18 @@ const RunKind = enum {
     LimitedFPS,
 };
 
-pub fn run(cpu: *Arm7tdmi, scheduler: *Scheduler, tracker: *Tracker, channel: *TwoWayChannel) void {
+pub fn run(cpu: *Arm7tdmi, scheduler: *Scheduler, tracker: *Tracker, rx: Channel.Receiver) void {
     const audio_sync = config.config().guest.audio_sync and !config.config().host.mute;
     if (audio_sync) log.info("Audio sync enabled", .{});
 
     if (config.config().guest.video_sync) {
-        inner(.LimitedFPS, audio_sync, cpu, scheduler, tracker, channel);
+        inner(.LimitedFPS, audio_sync, cpu, scheduler, tracker, rx);
     } else {
-        inner(.UnlimitedFPS, audio_sync, cpu, scheduler, tracker, channel);
+        inner(.UnlimitedFPS, audio_sync, cpu, scheduler, tracker, rx);
     }
 }
 
-fn inner(comptime kind: RunKind, audio_sync: bool, cpu: *Arm7tdmi, scheduler: *Scheduler, tracker: ?*Tracker, channel: *TwoWayChannel) void {
+fn inner(comptime kind: RunKind, audio_sync: bool, cpu: *Arm7tdmi, scheduler: *Scheduler, tracker: ?*Tracker, rx: Channel.Receiver) void {
     if (kind == .UnlimitedFPS or kind == .LimitedFPS) {
         std.debug.assert(tracker != null);
         log.info("FPS tracking enabled", .{});
@@ -59,13 +61,9 @@ fn inner(comptime kind: RunKind, audio_sync: bool, cpu: *Arm7tdmi, scheduler: *S
             log.info("Emulation w/out video sync", .{});
 
             while (true) {
-                if (channel.emu.pop()) |e| switch (e) {
+                if (rx.recv()) |m| switch (m) {
                     .Quit => break,
-                    .Resume => paused = false,
-                    .Pause => {
-                        paused = true;
-                        channel.gui.push(.Paused);
-                    },
+                    .Resume, .Pause => paused = m == .Pause,
                 };
 
                 if (paused) continue;
@@ -82,13 +80,9 @@ fn inner(comptime kind: RunKind, audio_sync: bool, cpu: *Arm7tdmi, scheduler: *S
             var wake_time: u64 = frame_period;
 
             while (true) {
-                if (channel.emu.pop()) |e| switch (e) {
+                if (rx.recv()) |m| switch (m) {
                     .Quit => break,
-                    .Resume => paused = false,
-                    .Pause => {
-                        paused = true;
-                        channel.gui.push(.Paused);
-                    },
+                    .Resume, .Pause => paused = m == .Pause,
                 };
 
                 if (paused) continue;

src/imgui.zig

@@ -56,7 +56,7 @@ pub const State = struct {
 
         return .{
             .title = handleTitle(title_opt),
-            .emulation = if (title_opt == null) .Inactive else .Active,
+            .emulation = if (title_opt == null) .Inactive else .{ .Transition = .Active },
             .fps_hist = RingBuffer(u32).init(history),
         };
     }

src/main.zig

@@ -6,7 +6,7 @@ const clap = @import("clap");
 const config = @import("config.zig");
 const emu = @import("core/emu.zig");
 
-const TwoWayChannel = @import("zba-util").TwoWayChannel;
+const Channel = @import("zba-util").Channel(emu.Message, 0x100);
 const Gui = @import("platform.zig").Gui;
 const Bus = @import("core/Bus.zig");
 const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
@@ -98,8 +98,8 @@ pub fn main() void {
 
     var quit = std.atomic.Atomic(bool).init(false);
 
-    var items: [0x100]u8 = undefined;
-    var channel = TwoWayChannel.init(&items);
+    var ch = Channel.init(allocator) catch |e| exitln("failed to initialize ui -> emu thread message channel: {}", .{e});
+    defer ch.deinit(allocator);
 
     if (result.args.gdb != 0) {
         const Server = @import("gdbstub").Server;
@@ -122,22 +122,22 @@ pub fn main() void {
         gui.run(.Debug, .{
             .cpu = &cpu,
             .scheduler = &scheduler,
-            .channel = &channel,
+            .ch = ch.tx,
         }) catch |e| exitln("main thread panicked: {}", .{e});
     } else {
         var tracker = FpsTracker.init();
 
         // emu should start paused if there's no ROM to run
         if (paths.rom == null)
-            channel.emu.push(.Pause);
+            ch.tx.send(.Pause);
 
-        const thread = std.Thread.spawn(.{}, emu.run, .{ &cpu, &scheduler, &tracker, &channel }) catch |e| exitln("emu thread panicked: {}", .{e});
+        const thread = std.Thread.spawn(.{}, emu.run, .{ &cpu, &scheduler, &tracker, ch.rx }) catch |e| exitln("emu thread panicked: {}", .{e});
         defer thread.join();
 
         gui.run(.Standard, .{
             .cpu = &cpu,
             .scheduler = &scheduler,
-            .channel = &channel,
+            .ch = ch.tx,
             .tracker = &tracker,
         }) catch |e| exitln("main thread panicked: {}", .{e});
     }

src/platform.zig

@@ -11,7 +11,7 @@ const Apu = @import("core/apu.zig").Apu;
 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 Channel = @import("zba-util").Channel(emu.Message, 0x100);
 const KeyInput = @import("core/bus/io.zig").KeyInput;
 
 const gba_width = @import("core/ppu.zig").width;
@@ -94,7 +94,7 @@ pub const Gui = struct {
     }
 
     const RunOptions = struct {
-        channel: *TwoWayChannel,
+        ch: Channel.Sender,
         tracker: ?*FpsTracker = null,
         cpu: *Arm7tdmi,
         scheduler: *Scheduler,
@@ -105,7 +105,7 @@ pub const Gui = struct {
     pub fn run(self: *Self, comptime mode: RunMode, opt: RunOptions) !void {
         const cpu = opt.cpu;
         const tracker = opt.tracker;
-        const channel = opt.channel;
+        const ch = opt.ch;
 
         const objects = opengl_impl.createObjects();
         defer gl.deleteBuffers(3, @as(*const [3]GLuint, &.{ objects.vao, objects.vbo, objects.ebo }));
@@ -193,50 +193,50 @@ pub const Gui = struct {
             switch (self.state.emulation) {
                 .Transition => |inner| switch (inner) {
                     .Active => {
-                        _ = channel.gui.pop();
+                        ch.send(.Resume);
+                        if (!config.config().host.mute) SDL.SDL_PauseAudioDevice(self.audio.device, 0);
 
-                        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);
+                        SDL.SDL_PauseAudioDevice(self.audio.device, 1);
+                        ch.send(.Pause);
+
                         self.state.emulation = .Inactive;
                     },
                 },
-                .Active => skip_draw: {
+                .Active => {
                     const is_std = mode == .Standard;
 
-                    if (is_std) channel.emu.push(.Pause);
-                    defer if (is_std) channel.emu.push(.Resume);
+                    if (is_std) ch.send(.Pause);
+                    defer if (is_std) ch.send(.Resume);
 
-                    switch (mode) {
-                        .Standard => blk: {
-                            const limit = 15; // TODO: What should this be?
+                    // 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;
+                    //         // TODO: learn more about std.atomic.spinLoopHint();
+                    //         for (0..limit) |_| {
+                    //             const message = channel.gui.pop() orelse continue;
 
-                                switch (message) {
-                                    .Paused => break :blk,
-                                    .Quit => unreachable,
-                                }
-                            }
+                    //             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...
-                            }
-                        },
-                    }
+                    //         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 {};
@@ -251,6 +251,12 @@ pub const Gui = struct {
                         opengl_impl.drawScreenTexture(emu_tex, prog_id, objects, buf);
                     }
 
+                    // FIXME: We only really care about locking the audio device (and therefore writing silence)
+                    // since if nfd-zig is used the emu may be paused for way too long. Perhaps we should try and limit
+                    // spurious calls to SDL_LockAudioDevice?
+                    SDL.SDL_LockAudioDevice(self.audio.device);
+                    defer SDL.SDL_UnlockAudioDevice(self.audio.device);
+
                     zgui_redraw = imgui.draw(&self.state, win_dim, out_tex, cpu);
                 },
                 .Inactive => zgui_redraw = imgui.draw(&self.state, win_dim, out_tex, cpu),
@@ -269,7 +275,7 @@ pub const Gui = struct {
             SDL.SDL_GL_SwapWindow(self.window);
         }
 
-        channel.emu.push(.Quit);
+        ch.send(.Quit);
     }
 
     fn glGetProcAddress(ctx: SDL.SDL_GLContext, proc: [:0]const u8) ?*anyopaque {
@@ -300,11 +306,6 @@ const Audio = struct {
         const device = SDL.SDL_OpenAudioDevice(null, 0, &want, &have, 0);
         if (device == 0) panic();
 
-        if (!config.config().host.mute) {
-            SDL.SDL_PauseAudioDevice(device, 0); // Unpause Audio
-            log.info("Unpaused Device", .{});
-        }
-
         return .{ .device = device };
     }