chore: be more intentional in atomic ordering use

src/core/emu.zig

@@ -56,7 +56,7 @@ fn inner(comptime kind: RunKind, audio_sync: bool, quit: *Atomic(bool), schedule
         .Unlimited, .UnlimitedFPS => {
             log.info("Emulation w/out video sync", .{});
 
-            while (!quit.load(.SeqCst)) {
+            while (!quit.load(.Monotonic)) {
                 runFrame(scheduler, cpu);
                 audioSync(audio_sync, cpu.bus.apu.stream, &cpu.bus.apu.is_buffer_full);
 
@@ -68,7 +68,7 @@ fn inner(comptime kind: RunKind, audio_sync: bool, quit: *Atomic(bool), schedule
             var timer = Timer.start() catch @panic("failed to initalize std.timer.Timer");
             var wake_time: u64 = frame_period;
 
-            while (!quit.load(.SeqCst)) {
+            while (!quit.load(.Monotonic)) {
                 runFrame(scheduler, cpu);
                 const new_wake_time = videoSync(&timer, wake_time);
 

src/core/ppu.zig

@@ -1464,7 +1464,7 @@ const FrameBuffer = struct {
 
     layers: [2][]u8,
     buf: []u8,
-    current: u1,
+    current: std.atomic.Atomic(u8),
 
     allocator: Allocator,
 
@@ -1483,7 +1483,7 @@ const FrameBuffer = struct {
             // Front and Back Framebuffers
             .layers = [_][]u8{ buf[0..][0..framebuf_len], buf[framebuf_len..][0..framebuf_len] },
             .buf = buf,
-            .current = 0,
+            .current = std.atomic.Atomic(u8).init(0),
 
             .allocator = allocator,
         };
@@ -1495,10 +1495,12 @@ const FrameBuffer = struct {
     }
 
     pub fn swap(self: *Self) void {
-        self.current = ~self.current;
+        _ = self.current.fetchXor(1, .Release); // fetchNot(.Release)
     }
 
     pub fn get(self: *Self, comptime dev: Device) []u8 {
-        return self.layers[if (dev == .Emulator) self.current else ~self.current];
+        const current = @intCast(u1, self.current.load(.Acquire));
+
+        return self.layers[if (dev == .Emulator) current else ~current];
     }
 };