README.md

@@ -2,7 +2,7 @@
 An in-progress Gameboy Advance Emulator written in Zig ⚡!
 
 ## Tests 
-- [ ] [jsmolka's GBA Test Collection](https://github.com/jsmolka/gba-tests)
+- [ ] [jsmolka GBA Test Collection](https://github.com/jsmolka/gba-tests)
     - [x] `arm.gba` and `thumb.gba`
     - [x] `flash64.gba`, `flash128.gba`, `none.gba`, and `sram.gba`
     - [x] `hello.gba`, `shades.gba`, and `stripes.gba`

src/apu.zig

@@ -31,6 +31,7 @@ pub const Apu = struct {
 
     sampling_cycle: u2,
 
+    // TODO: Research whether we can have Atomic Pointers
     stream: *SDL.SDL_AudioStream,
     sched: *Scheduler,
 
@@ -206,6 +207,83 @@ pub const Apu = struct {
         self.sched.push(.SampleAudio, self.sampleTicks() -| late);
     }
 
+    // pub fn sampleAudio(self: *Self, late: u64) void {
+    //     // zig fmt: off
+    //     const any_ch_enabled = self.ch1.enabled
+    //         or self.ch2.enabled
+    //         or self.ch3.enabled
+    //         or self.ch4.enabled;
+    //     // zig fmt: on
+
+    //     const ch_left: u4 = self.psg_cnt.ch_left.read();
+    //     const ch_right: u4 = self.psg_cnt.ch_right.read();
+
+    //     // FIXME: Obscure behaviour?
+    //     // Apply NR50 Volume Modifications
+    //     const left_master_vol = (@intToFloat(f32, self.psg_cnt.left_vol.read()) + 1.0) / 7.0;
+    //     const right_master_vol = (@intToFloat(f32, self.psg_cnt.right_vol.read()) + 1.0) / 7.0;
+
+    //     // Apply SOUNDCNT_H Volume Modifications
+    //     const gba_vol: f32 = switch (self.dma_cnt.ch_vol.read()) {
+    //         0b00 => 0.25,
+    //         0b01 => 0.5,
+    //         else => 1.0,
+    //     };
+
+    //     // Sample Channel 1
+    //     const ch1_sample = self.highPass(self.ch1.amplitude(), any_ch_enabled);
+    //     const ch1_left = if (ch_left & 1 == 1) ch1_sample else 0;
+    //     const ch1_right = if (ch_right & 1 == 1) ch1_sample else 0;
+
+    //     // Sample Channel 2
+    //     const ch2_sample = self.highPass(self.ch2.amplitude(), any_ch_enabled);
+    //     const ch2_left = if (ch_left >> 1 & 1 == 1) ch2_sample else 0;
+    //     const ch2_right = if (ch_right >> 1 & 1 == 1) ch2_sample else 0;
+
+    //     // Sample Channel 3
+    //     const ch3_sample = self.highPass(self.ch3.amplitude(), any_ch_enabled);
+    //     const ch3_left = if (ch_left >> 2 & 1 == 1) ch3_sample else 0;
+    //     const ch3_right = if (ch_right >> 2 & 1 == 1) ch3_sample else 0;
+
+    //     // Sample Channel 4
+    //     const ch4_sample = self.highPass(self.ch4.amplitude(), any_ch_enabled);
+    //     const ch4_left = if (ch_left >> 3 == 1) ch4_sample else 0;
+    //     const ch4_right = if (ch_right >> 3 == 1) ch4_sample else 0;
+
+    //     const psg_left = (ch1_left + ch2_left + ch3_left + ch4_left) * left_master_vol * gba_vol;
+    //     const psg_right = (ch1_right + ch2_right + ch3_right + ch4_right) * right_master_vol * gba_vol;
+
+    //     // Sample Dma Channels
+    //     const chA_sample = if (self.dma_cnt.chA_vol.read()) self.chA.amplitude() * 4 else self.chA.amplitude() * 2;
+    //     const chA_left = if (self.dma_cnt.chA_left.read()) chA_sample else 0;
+    //     const chA_right = if (self.dma_cnt.chA_right.read()) chA_sample else 0;
+
+    //     const chB_sample = if (self.dma_cnt.chB_vol.read()) self.chB.amplitude() * 4 else self.chB.amplitude() * 2;
+    //     const chB_left = if (self.dma_cnt.chB_left.read()) chB_sample else 0;
+    //     const chB_right = if (self.dma_cnt.chB_right.read()) chB_sample else 0;
+
+    //     // Mix all Channels
+    //     const left = (chA_left + chB_left + psg_left) / 6.0;
+    //     const right = (chA_right + chB_right + psg_right) / 6.0;
+
+    //     if (self.sampling_cycle != self.bias.sampling_cycle.read()) {
+    //         log.info("Sampling Cycle changed from {} to {}", .{ self.sampling_cycle, self.bias.sampling_cycle.read() });
+
+    //         // Sample Rate Changed, Create a new Resampler since i can't figure out how to change
+    //         // the parameters of the old one
+    //         const old = self.stream;
+    //         defer SDL.SDL_FreeAudioStream(old);
+
+    //         self.sampling_cycle = self.bias.sampling_cycle.read();
+    //         self.stream = SDL.SDL_NewAudioStream(SDL.AUDIO_F32, 2, @intCast(c_int, self.sampleRate()), SDL.AUDIO_F32, 2, host_sample_rate) orelse unreachable;
+    //     }
+
+    //     while (SDL.SDL_AudioStreamAvailable(self.stream) > (@sizeOf(f32) * 2 * 0x800)) {}
+
+    //     _ = SDL.SDL_AudioStreamPut(self.stream, &[2]f32{ left, right }, 2 * @sizeOf(f32));
+    //     self.sched.push(.SampleAudio, self.sampleTicks() -| late);
+    // }
+
     fn sampleTicks(self: *const Self) u64 {
         return (1 << 24) / self.sampleRate();
     }

src/bus/Bios.zig

@@ -33,7 +33,9 @@ pub fn deinit(self: Self) void {
 
 pub fn checkedRead(self: *Self, comptime T: type, r15: u32, addr: u32) T {
     if (r15 < Self.size) {
+        // FIXME: Just give up on *const Self on bus reads, Rekai
         self.addr_latch = addr;
+
         return self.read(T, addr);
     }
 

src/bus/backup.zig

@@ -411,18 +411,10 @@ const Eeprom = struct {
                     .Large => {
                         if (self.writer.len() == 14) {
                             const addr = @intCast(u10, self.writer.finish());
-                            const value_buf = buf[@as(u13, addr) * 8 ..][0..8];
 
-                            // zig fmt: off
-                            const value = @as(u64, value_buf[7]) << 56
-                                | @as(u64, value_buf[6]) << 48
-                                | @as(u64, value_buf[5]) << 40
-                                | @as(u64, value_buf[4]) << 32
-                                | @as(u64, value_buf[3]) << 24
-                                | @as(u64, value_buf[2]) << 16
-                                | @as(u64, value_buf[1]) << 8
-                                | @as(u64, value_buf[0]) << 0;
-                            // zig fmt: on
+                            // TODO: Bit Verbose eh?
+                            const value_buf = buf[@as(u13, addr) * 8 ..][0..8];
+                            const value = @as(u64, value_buf[7]) << 56 | @as(u64, value_buf[6]) << 48 | @as(u64, value_buf[5]) << 40 | @as(u64, value_buf[4]) << 32 | @as(u64, value_buf[3]) << 24 | @as(u64, value_buf[2]) << 16 | @as(u64, value_buf[1]) << 8 | @as(u64, value_buf[0]) << 0;
 
                             self.reader.configure(value);
                             self.state = .RequestEnd;
@@ -430,20 +422,11 @@ const Eeprom = struct {
                     },
                     .Small => {
                         if (self.writer.len() == 6) {
-                            // FIXME: Duplicated code from above
                             const addr = @intCast(u6, self.writer.finish());
-                            const value_buf = buf[@as(u13, addr) * 8 ..][0..8];
 
-                            // zig fmt: off
-                            const value = @as(u64, value_buf[7]) << 56
-                                | @as(u64, value_buf[6]) << 48
-                                | @as(u64, value_buf[5]) << 40
-                                | @as(u64, value_buf[4]) << 32
-                                | @as(u64, value_buf[3]) << 24
-                                | @as(u64, value_buf[2]) << 16
-                                | @as(u64, value_buf[1]) << 8
-                                | @as(u64, value_buf[0]) << 0;
-                            // zig fmt: on
+                            // TODO: Bit Verbose eh?, also duplicate code
+                            const value_buf = buf[@as(u13, addr) * 8 ..][0..8];
+                            const value = @as(u64, value_buf[7]) << 56 | @as(u64, value_buf[6]) << 48 | @as(u64, value_buf[5]) << 40 | @as(u64, value_buf[4]) << 32 | @as(u64, value_buf[3]) << 24 | @as(u64, value_buf[2]) << 16 | @as(u64, value_buf[1]) << 8 | @as(u64, value_buf[0]) << 0;
 
                             self.reader.configure(value);
                             self.state = .RequestEnd;

src/cpu.zig

@@ -451,6 +451,7 @@ inline fn thumbIdx(opcode: u16) u10 {
 }
 
 pub fn checkCond(cpsr: PSR, cond: u4) bool {
+    // TODO: Should I implement an enum?
     return switch (cond) {
         0x0 => cpsr.z.read(), // EQ - Equal
         0x1 => !cpsr.z.read(), // NE - Not equal

src/emu.zig

@@ -79,7 +79,7 @@ pub fn runUnsynchronized(quit: *Atomic(bool), sched: *Scheduler, cpu: *Arm7tdmi,
             runFrame(sched, cpu);
             if (audio_sync) syncToAudio(cpu);
 
-            tracker.tick();
+            tracker.completeFrame();
         }
     } else {
         while (!quit.load(.SeqCst)) {
@@ -108,7 +108,7 @@ pub fn runSynchronized(quit: *Atomic(bool), sched: *Scheduler, cpu: *Arm7tdmi, f
             if (audio_sync) syncToAudio(cpu) else spinLoop(&timer, wake_time);
             wake_time = new_wake_time;
 
-            tracker.tick();
+            tracker.completeFrame();
         }
     } else {
         while (!quit.load(.SeqCst)) {

src/util.zig

@@ -37,12 +37,16 @@ pub const FpsTracker = struct {
         };
     }
 
-    pub fn tick(self: *Self) void {
+    // TODO: Rename
+    pub fn completeFrame(self: *Self) void {
         _ = self.count.fetchAdd(1, .Monotonic);
     }
 
     pub fn value(self: *Self) u32 {
-        if (self.timer.read() >= std.time.ns_per_s) {
+        const expected = @intToFloat(f64, std.time.ns_per_s);
+        const actual = @intToFloat(f64, self.timer.read());
+
+        if (actual >= expected) {
             self.fps = self.count.swap(0, .SeqCst);
             self.timer.reset();
         }