1/* Copyright (c) 2013-2014 Jeffrey Pfau
  2 *
  3 * This Source Code Form is subject to the terms of the Mozilla Public
  4 * License, v. 2.0. If a copy of the MPL was not distributed with this
  5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
  6#include "sdl-audio.h"
  7
  8#include "gba.h"
  9#include "gba-thread.h"
 10
 11#if RESAMPLE_LIBRARY == RESAMPLE_BLIP_BUF
 12#include "third-party/blip_buf/blip_buf.h"
 13#endif
 14
 15#define BUFFER_SIZE (GBA_AUDIO_SAMPLES >> 2)
 16
 17static void _GBASDLAudioCallback(void* context, Uint8* data, int len);
 18
 19bool GBASDLInitAudio(struct GBASDLAudio* context, struct GBAThread* threadContext) {
 20	if (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0) {
 21		GBALog(0, GBA_LOG_ERROR, "Could not initialize SDL sound system");
 22		return false;
 23	}
 24
 25	context->desiredSpec.freq = 44100;
 26	context->desiredSpec.format = AUDIO_S16SYS;
 27	context->desiredSpec.channels = 2;
 28	context->desiredSpec.samples = context->samples;
 29	context->desiredSpec.callback = _GBASDLAudioCallback;
 30	context->desiredSpec.userdata = context;
 31#if RESAMPLE_LIBRARY == RESAMPLE_NN
 32	context->drift = 0.f;
 33#endif
 34	if (SDL_OpenAudio(&context->desiredSpec, &context->obtainedSpec) < 0) {
 35		GBALog(0, GBA_LOG_ERROR, "Could not open SDL sound system");
 36		return false;
 37	}
 38	context->thread = threadContext;
 39	context->samples = context->obtainedSpec.samples;
 40	float ratio = GBAAudioCalculateRatio(0x8000, threadContext->fpsTarget, 44100);
 41	threadContext->audioBuffers = context->samples / ratio;
 42	if (context->samples > threadContext->audioBuffers) {
 43		threadContext->audioBuffers = context->samples * 2;
 44	}
 45
 46	SDL_PauseAudio(0);
 47	return true;
 48}
 49
 50void GBASDLDeinitAudio(struct GBASDLAudio* context) {
 51	UNUSED(context);
 52	SDL_PauseAudio(1);
 53	SDL_CloseAudio();
 54	SDL_QuitSubSystem(SDL_INIT_AUDIO);
 55}
 56
 57void GBASDLPauseAudio(struct GBASDLAudio* context) {
 58	UNUSED(context);
 59	SDL_PauseAudio(1);
 60}
 61
 62void GBASDLResumeAudio(struct GBASDLAudio* context) {
 63	UNUSED(context);
 64	SDL_PauseAudio(0);
 65}
 66
 67static void _GBASDLAudioCallback(void* context, Uint8* data, int len) {
 68	struct GBASDLAudio* audioContext = context;
 69	if (!context || !audioContext->thread || !audioContext->thread->gba) {
 70		memset(data, 0, len);
 71		return;
 72	}
 73#if RESAMPLE_LIBRARY == RESAMPLE_NN
 74	audioContext->ratio = GBAAudioCalculateRatio(audioContext->thread->gba->audio.sampleRate, audioContext->thread->fpsTarget, audioContext->obtainedSpec.freq);
 75	if (audioContext->ratio == INFINITY) {
 76		memset(data, 0, len);
 77		return;
 78	}
 79	struct GBAStereoSample* ssamples = (struct GBAStereoSample*) data;
 80	len /= 2 * audioContext->obtainedSpec.channels;
 81	if (audioContext->obtainedSpec.channels == 2) {
 82		GBAAudioResampleNN(&audioContext->thread->gba->audio, audioContext->ratio, &audioContext->drift, ssamples, len);
 83	}
 84#elif RESAMPLE_LIBRARY == RESAMPLE_BLIP_BUF
 85	double fauxClock = GBAAudioCalculateRatio(1, audioContext->thread->fpsTarget, 1);
 86	GBASyncLockAudio(&audioContext->thread->sync);
 87	blip_set_rates(audioContext->thread->gba->audio.left, GBA_ARM7TDMI_FREQUENCY, audioContext->obtainedSpec.freq * fauxClock);
 88	blip_set_rates(audioContext->thread->gba->audio.right, GBA_ARM7TDMI_FREQUENCY, audioContext->obtainedSpec.freq * fauxClock);
 89	len /= 2 * audioContext->obtainedSpec.channels;
 90	int available = blip_samples_avail(audioContext->thread->gba->audio.left);
 91	if (available > len) {
 92		available = len;
 93	}
 94	blip_read_samples(audioContext->thread->gba->audio.left, (short*) data, available, audioContext->obtainedSpec.channels == 2);
 95	if (audioContext->obtainedSpec.channels == 2) {
 96		blip_read_samples(audioContext->thread->gba->audio.right, ((short*) data) + 1, available, 1);
 97	}
 98	GBASyncConsumeAudio(&audioContext->thread->sync);
 99	if (available < len) {
100		memset(((short*) data) + audioContext->obtainedSpec.channels * available, 0, len - available);
101	}
102#endif
103}