Replace SDL2 audio with XAudio2 on Windows

Makefile

@@ -17,9 +17,11 @@ ifeq ($(PLATFORM),windows32)
 _ := $(shell chcp 65001)
 EXESUFFIX:=.exe
 NATIVE_CC = clang -IWindows -Wno-deprecated-declarations --target=i386-pc-windows
+SDL_AUDIO_DRIVER ?= xaudio2
 else
 EXESUFFIX:=
 NATIVE_CC := cc
+SDL_AUDIO_DRIVER ?= sdl
 endif
 
 PB12_COMPRESS := build/pb12$(EXESUFFIX)
@@ -47,7 +49,6 @@ endif
 include version.mk
 export VERSION
 CONF ?= debug
-SDL_AUDIO_DRIVER ?= sdl
 
 BIN := build/bin
 OBJ := build/obj

SDL/audio/xaudio2.c

@@ -0,0 +1,110 @@
+#include "audio.h"
+#include <Windows.h>
+#include <xaudio2.h>
+
+#define AUDIO_FREQUENCY 96000
+static IXAudio2 *xaudio2 = NULL;
+static IXAudio2MasteringVoice *master_voice = NULL;
+static IXAudio2SourceVoice *source_voice = NULL;
+static bool playing = false;
+static GB_sample_t sample_pool[0x2000];
+static unsigned pos = 0;
+
+#define BATCH_SIZE 256
+
+static const WAVEFORMATEX wave_format = {
+    .wFormatTag = WAVE_FORMAT_PCM,
+    .nChannels = 2,
+    .nSamplesPerSec = AUDIO_FREQUENCY,
+    .nAvgBytesPerSec = AUDIO_FREQUENCY * 4,
+    .nBlockAlign = 4,
+    .wBitsPerSample = 16,
+    .cbSize = 0
+};
+
+bool GB_audio_is_playing(void)
+{
+    return playing;
+}
+
+void GB_audio_set_paused(bool paused)
+{
+    if (paused) {
+        playing = false;
+        IXAudio2SourceVoice_Stop(source_voice, 0, XAUDIO2_COMMIT_NOW);
+        GB_audio_clear_queue();
+    }
+    else {
+        playing = true;
+        IXAudio2SourceVoice_Start(source_voice, 0, XAUDIO2_COMMIT_NOW);
+    }
+    
+}
+
+void GB_audio_clear_queue(void)
+{
+    pos = 0;
+    IXAudio2SourceVoice_FlushSourceBuffers(source_voice);
+}
+
+unsigned GB_audio_get_frequency(void)
+{
+    return AUDIO_FREQUENCY;
+}
+
+size_t GB_audio_get_queue_length(void)
+{
+    static XAUDIO2_VOICE_STATE state;
+    IXAudio2SourceVoice_GetState(source_voice, &state, XAUDIO2_VOICE_NOSAMPLESPLAYED);
+    
+    return state.BuffersQueued * BATCH_SIZE + (pos & (BATCH_SIZE - 1));
+}
+
+void GB_audio_queue_sample(GB_sample_t *sample)
+{
+    if (!playing) return;
+        
+    static XAUDIO2_BUFFER buffer = {.AudioBytes = sizeof(*sample) * BATCH_SIZE, };
+    sample_pool[pos] = *sample;
+    buffer.pAudioData = (void *)&sample_pool[pos & ~(BATCH_SIZE - 1)];
+    pos++;
+    pos &= 0x1fff;
+    if ((pos & (BATCH_SIZE - 1)) == 0) {
+        IXAudio2SourceVoice_SubmitSourceBuffer(source_voice, &buffer, NULL);
+    }
+}
+
+void GB_audio_init(void)
+{
+    HRESULT hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
+    if (FAILED(hr)) {
+        fprintf(stderr, "CoInitializeEx failed: %lx\n", hr);
+        return;
+    }
+    
+    hr = XAudio2Create(&xaudio2, 0, XAUDIO2_DEFAULT_PROCESSOR);
+    if (FAILED(hr)) {
+        fprintf(stderr, "XAudio2Create failed: %lx\n", hr);
+        return;
+    }
+    
+    hr = IXAudio2_CreateMasteringVoice(xaudio2, &master_voice,
+                                       2, // 2 channels
+                                       AUDIO_FREQUENCY,
+                                       0, // Flags
+                                       0, // Device index
+                                       NULL, // Effect chain
+                                       AudioCategory_GameMedia // Category
+                                      );
+    if (FAILED(hr)) {
+        fprintf(stderr, "CreateMasteringVoice failed: %lx\n", hr);
+        return;
+    }
+    
+    hr = IXAudio2_CreateSourceVoice(xaudio2, &source_voice, &wave_format, 0, XAUDIO2_DEFAULT_FREQ_RATIO, NULL, NULL, NULL);
+    
+    if (FAILED(hr)) {
+        fprintf(stderr, "CreateSourceVoice failed: %lx\n", hr);
+        return;
+    }
+}