feat: allow gui and gdbstub to run in parallel

lib/zba-gdbstub

@@ -1 +1 @@
-Subproject commit c1158b547e54d82f5ac7aba4cf372c6e061b1eab
+Subproject commit 6d6a109a086361d300da675db8445ede74be58f6

src/core/emu.zig

@@ -200,15 +200,18 @@ pub const EmuThing = struct {
         const cpu = self.cpu;
         const sched = self.scheduler;
 
+        // Is true when we have executed one (1) instruction
+        var did_step: bool = false;
+
         // TODO: How can I make it easier to keep this in lock-step with runFrame?
-        while (true) {
+        while (!did_step) {
             if (!cpu.stepDmaTransfer()) {
                 if (cpu.isHalted()) {
                     // Fast-forward to next Event
                     sched.tick = sched.queue.peek().?.tick;
                 } else {
                     cpu.step();
-                    break; // this function won't return until we've actually stepped once
+                    did_step = true;
                 }
             }
 

src/core/ppu.zig

@@ -990,8 +990,7 @@ pub const Ppu = struct {
             cpu.handleInterrupt();
         }
 
-        // See if HBlank DMA is present and not enabled
-
+        // If we're not also in VBlank, attempt to run any pending DMA Reqs
         if (!self.dispstat.vblank.read())
             dma.onBlanking(cpu.bus, .HBlank);
 

src/main.zig

@@ -4,14 +4,17 @@ const known_folders = @import("known_folders");
 const clap = @import("clap");
 
 const config = @import("config.zig");
+const emu = @import("core/emu.zig");
 
 const Gui = @import("platform.zig").Gui;
 const Bus = @import("core/Bus.zig");
 const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
 const Scheduler = @import("core/scheduler.zig").Scheduler;
 const FilePaths = @import("util.zig").FilePaths;
-
+const FpsTracker = @import("util.zig").FpsTracker;
 const Allocator = std.mem.Allocator;
+const Atomic = std.atomic.Atomic;
+
 const log = std.log.scoped(.Cli);
 const width = @import("core/ppu.zig").width;
 const height = @import("core/ppu.zig").height;
@@ -88,6 +91,10 @@ pub fn main() void {
         cpu.fastBoot();
     }
 
+    var quit = Atomic(bool).init(false);
+    var gui = Gui.init(&bus.pak.title, &bus.apu, width, height) catch |e| exitln("failed to init gui: {}", .{e});
+    defer gui.deinit();
+
     if (result.args.gdb) {
         const Server = @import("gdbstub").Server;
         const EmuThing = @import("core/emu.zig").EmuThing;
@@ -96,29 +103,33 @@ pub fn main() void {
         var emulator = wrapper.interface(allocator);
         defer emulator.deinit();
 
-        {
-            const frames_per_second: usize = 60;
-            const emu = @import("core/emu.zig");
-
-            var i: usize = 0;
-            while (i < frames_per_second * 120) : (i += 1) {
-                emu.runFrame(&scheduler, &cpu);
-
-                std.debug.print("Frame {:0>3}/{:0>3}\r", .{ i, frames_per_second * 120 });
-            }
-        }
-
         log.info("Ready to connect", .{});
 
         var server = Server.init(emulator) catch |e| exitln("failed to init gdb server: {}", .{e});
         defer server.deinit(allocator);
 
-        server.run(allocator) catch |e| exitln("gdb server crashed: {}", .{e});
-    } else {
-        var gui = Gui.init(&bus.pak.title, &bus.apu, width, height) catch |e| exitln("failed to init gui: {}", .{e});
-        defer gui.deinit();
+        log.info("Starting GDB Server Thread", .{});
 
-        gui.run(&cpu, &scheduler) catch |e| exitln("failed to run gui thread: {}", .{e});
+        const thread = std.Thread.spawn(.{}, Server.run, .{ &server, allocator, &quit }) catch |e| exitln("gdb server thread crashed: {}", .{e});
+        defer thread.join();
+
+        gui.run(.{
+            .cpu = &cpu,
+            .scheduler = &scheduler,
+            .quit = &quit,
+        }) catch |e| exitln("main thread panicked: {}", .{e});
+    } else {
+        var tracker = FpsTracker.init();
+
+        const thread = std.Thread.spawn(.{}, emu.run, .{ &quit, &scheduler, &cpu, &tracker }) catch |e| exitln("emu thread panicked: {}", .{e});
+        defer thread.join();
+
+        gui.run(.{
+            .cpu = &cpu,
+            .scheduler = &scheduler,
+            .tracker = &tracker,
+            .quit = &quit,
+        }) catch |e| exitln("main thread panicked: {}", .{e});
     }
 }
 

src/platform.zig

@@ -154,9 +154,17 @@ pub const Gui = struct {
         return tex_id;
     }
 
-    pub fn run(self: *Self, cpu: *Arm7tdmi, scheduler: *Scheduler) !void {
-        var quit = std.atomic.Atomic(bool).init(false);
-        var tracker = FpsTracker.init();
+    const RunOptions = struct {
+        quit: *std.atomic.Atomic(bool),
+        tracker: ?*FpsTracker = null,
+        cpu: *Arm7tdmi,
+        scheduler: *Scheduler,
+    };
+
+    pub fn run(self: *Self, opt: RunOptions) !void {
+        const cpu = opt.cpu;
+        const tracker = opt.tracker;
+        const quit = opt.quit;
 
         var buffer_ids = Self.generateBuffers();
         defer {
@@ -169,13 +177,15 @@ pub const Gui = struct {
         const tex_id = Self.generateTexture(cpu.bus.ppu.framebuf.get(.Renderer));
         defer gl.deleteTextures(1, &tex_id);
 
-        const thread = try std.Thread.spawn(.{}, emu.run, .{ &quit, scheduler, cpu, &tracker });
-        defer thread.join();
-
         var title_buf: [0x100]u8 = undefined;
 
         emu_loop: while (true) {
             var event: SDL.SDL_Event = undefined;
+
+            // This might be true if the emu is running via a gdbstub server
+            // and the gdb stub exits first
+            if (quit.load(.Monotonic)) break :emu_loop;
+
             while (SDL.SDL_PollEvent(&event) != 0) {
                 switch (event.type) {
                     SDL.SDL_QUIT => break :emu_loop,
@@ -238,8 +248,10 @@ pub const Gui = struct {
             gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_INT, null);
             SDL.SDL_GL_SwapWindow(self.window);
 
-            const dyn_title = std.fmt.bufPrintZ(&title_buf, "ZBA | {s} [Emu: {}fps] ", .{ self.title, tracker.value() }) catch unreachable;
-            SDL.SDL_SetWindowTitle(self.window, dyn_title.ptr);
+            if (tracker) |t| {
+                const dyn_title = std.fmt.bufPrintZ(&title_buf, "ZBA | {s} [Emu: {}fps] ", .{ self.title, t.value() }) catch unreachable;
+                SDL.SDL_SetWindowTitle(self.window, dyn_title.ptr);
+            }
         }
 
         quit.store(true, .Monotonic); // Terminate Emulator Thread