Hook up audio for DMA sound channels

src/gba/gba-audio.c

@@ -3,7 +3,7 @@
 #include "gba.h"
 #include "gba-io.h"
 
-const unsigned GBA_AUDIO_SAMPLES = 4096 * sizeof(int32_t);
+const unsigned GBA_AUDIO_SAMPLES = 1024;
 const unsigned GBA_AUDIO_FIFO_SIZE = 8 * sizeof(int32_t);
 
 static void _sample(struct GBAAudio* audio);
@@ -15,8 +15,8 @@ void GBAAudioInit(struct GBAAudio* audio) {
 	audio->sampleRate = 0x8000;
 	audio->sampleInterval = GBA_ARM7TDMI_FREQUENCY / audio->sampleRate;
 
-	CircleBufferInit(&audio->left, GBA_AUDIO_SAMPLES);
+	CircleBufferInit(&audio->left, GBA_AUDIO_SAMPLES * sizeof(int32_t));
-	CircleBufferInit(&audio->right, GBA_AUDIO_SAMPLES);
+	CircleBufferInit(&audio->right, GBA_AUDIO_SAMPLES * sizeof(int32_t));
 	CircleBufferInit(&audio->chA.fifo, GBA_AUDIO_FIFO_SIZE);
 	CircleBufferInit(&audio->chB.fifo, GBA_AUDIO_FIFO_SIZE);
 }
@@ -148,13 +148,29 @@ void GBAAudioSampleFIFO(struct GBAAudio* audio, int fifoId) {
 		dma->nextCount = 4;
 		GBAMemoryServiceDMA(&audio->p->memory, channel->dmaSource, dma);
 	}
-	CircleBufferRead32(&channel->fifo, &channel->sample);
+	CircleBufferRead8(&channel->fifo, &channel->sample);
 }
 
 static void _sample(struct GBAAudio* audio) {
 	int32_t sampleLeft = 0;
 	int32_t sampleRight = 0;
 
+	if (audio->chALeft) {
+		sampleLeft += audio->chA.sample;
+	}
+
+	if (audio->chARight) {
+		sampleRight += audio->chA.sample;
+	}
+
+	if (audio->chBLeft) {
+		sampleLeft += audio->chB.sample;
+	}
+
+	if (audio->chBRight) {
+		sampleRight += audio->chB.sample;
+	}
+
 	CircleBufferWrite32(&audio->left, sampleLeft);
 	CircleBufferWrite32(&audio->right, sampleRight);
 }

src/gba/gba-audio.h

@@ -7,6 +7,8 @@
 
 struct GBADMA;
 
+const unsigned GBA_AUDIO_SAMPLES;
+
 union GBAAudioWave {
 	struct {
 		unsigned length : 6;
@@ -100,7 +102,7 @@ struct GBAAudioChannel4 {
 struct GBAAudioFIFO {
 	struct CircleBuffer fifo;
 	int dmaSource;
-	int32_t sample;
+	int8_t sample;
 };
 
 struct GBAAudio {

src/gl-main.c

@@ -1,6 +1,7 @@
 #include "debugger.h"
 #include "gba-thread.h"
 #include "gba.h"
+#include "sdl-audio.h"
 #include "sdl-events.h"
 #include "renderers/video-software.h"
 
@@ -19,6 +20,8 @@
 
 struct GLSoftwareRenderer {
 	struct GBAVideoSoftwareRenderer d;
+	struct GBASDLAudio audio;
+	struct GBASDLEvents events;
 
 	GLuint tex;
 };
@@ -69,6 +72,7 @@ int main(int argc, char** argv) {
 	context.useDebugger = 1;
 	context.renderer = &renderer.d.d;
 	GBAThreadStart(&context);
+	renderer.audio.audio = &context.gba->audio;
 
 	_GBASDLRunloop(&context, &renderer);
 
@@ -85,7 +89,8 @@ static int _GBASDLInit(struct GLSoftwareRenderer* renderer) {
 		return 0;
 	}
 
-	GBASDLInitEvents();
+	GBASDLInitEvents(&renderer->events);
+	GBASDLInitAudio(&renderer->audio);
 
 	SDL_GL_SetAttribute(SDL_GL_SWAP_CONTROL, 1);
 	SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
@@ -155,6 +160,7 @@ static void _GBASDLRunloop(struct GBAThread* context, struct GLSoftwareRenderer*
 static void _GBASDLDeinit(struct GLSoftwareRenderer* renderer) {
 	free(renderer->d.outputBuffer);
 
-	GBASDLDeinitEvents();
+	GBASDLDeinitEvents(&renderer->events);
+	GBASDLDeinitAudio(&renderer->audio);
 	SDL_Quit();
 }

src/sdl/sdl-audio.c

@@ -0,0 +1,70 @@
+#include "sdl-audio.h"
+
+#include "gba.h"
+
+static void _GBASDLAudioCallback(void* context, Uint8* data, int len);
+
+int GBASDLInitAudio(struct GBASDLAudio* context) {
+	if (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0) {
+		GBALog(0, GBA_LOG_ERROR, "Could not initialize SDL sound system");
+		return 0;
+	}
+
+	context->desiredSpec.freq = 44100;
+	context->desiredSpec.format = AUDIO_S16SYS;
+	context->desiredSpec.channels = 2;
+	context->desiredSpec.samples = GBA_AUDIO_SAMPLES >> 1;
+	context->desiredSpec.callback = _GBASDLAudioCallback;
+	context->desiredSpec.userdata = context;
+	context->audio = 0;
+	context->drift = 0.f;
+	if (SDL_OpenAudio(&context->desiredSpec, &context->obtainedSpec) < 0) {
+		GBALog(0, GBA_LOG_ERROR, "Could not open SDL sound system");
+		return 0;
+	}
+	SDL_PauseAudio(0);
+	return 1;
+}
+
+void GBASDLDeinitAudio(struct GBASDLAudio* context) {
+	(void)(context);
+	SDL_CloseAudio();
+	SDL_QuitSubSystem(SDL_INIT_AUDIO);
+}
+
+static void _pulldownResample(struct GBASDLAudio* context) {
+	int32_t value;
+	if (CircleBufferRead32(&context->audio->left, &value)) {
+		context->currentSample.left = value << 7;
+	} else {
+		context->currentSample.left = 0;
+	}
+	if (CircleBufferRead32(&context->audio->right, &value)) {
+		context->currentSample.right = value << 7;
+	} else {
+		context->currentSample.right = 0;
+	}
+}
+
+static void _GBASDLAudioCallback(void* context, Uint8* data, int len) {
+	struct GBASDLAudio* audioContext = context;
+	int i;
+	if (!context || !audioContext->audio) {
+		for (i = 0; i < len; ++i) {
+			data[i] = 0;
+		}
+		return;
+	}
+	struct StereoSample* ssamples = (struct StereoSample*) data;
+	len /= 2 * audioContext->obtainedSpec.channels;
+	if (audioContext->obtainedSpec.channels == 2) {
+		for (i = 0; i < len; ++i) {
+			audioContext->drift += audioContext->audio->sampleRate / (float) audioContext->obtainedSpec.freq;
+			while (audioContext->drift >= 0) {
+				_pulldownResample(audioContext);
+				audioContext->drift -= 1.f;
+			}
+			ssamples[i] = audioContext->currentSample;
+		}
+	}
+}

src/sdl/sdl-audio.h

@@ -0,0 +1,22 @@
+#ifndef SDL_AUDIO_H
+#define SDL_AUDIO_H
+
+#include <SDL.h>
+
+struct StereoSample {
+	Sint16 left;
+	Sint16 right;
+};
+
+struct GBASDLAudio {
+	SDL_AudioSpec desiredSpec;
+	SDL_AudioSpec obtainedSpec;
+	float drift;
+	struct GBAAudio* audio;
+	struct StereoSample currentSample;
+};
+
+int GBASDLInitAudio(struct GBASDLAudio* context);
+void GBASDLDeinitAudio(struct GBASDLAudio* context);
+
+#endif