1/* Copyright (c) 2013-2015 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 "core/thread.h"
  9#include "gba/gba.h"
 10
 11#include "third-party/blip_buf/blip_buf.h"
 12
 13#define BUFFER_SIZE (GBA_AUDIO_SAMPLES >> 2)
 14
 15mLOG_DEFINE_CATEGORY(SDL_AUDIO, "SDL Audio");
 16
 17static void _mSDLAudioCallback(void* context, Uint8* data, int len);
 18
 19bool mSDLInitAudio(struct mSDLAudio* context, struct mCoreThread* threadContext) {
 20	if (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0) {
 21		mLOG(SDL_AUDIO, ERROR, "Could not initialize SDL sound system: %s", SDL_GetError());
 22		return false;
 23	}
 24
 25	context->desiredSpec.freq = context->sampleRate;
 26	context->desiredSpec.format = AUDIO_S16SYS;
 27	context->desiredSpec.channels = 2;
 28	context->desiredSpec.samples = context->samples;
 29	context->desiredSpec.callback = _mSDLAudioCallback;
 30	context->desiredSpec.userdata = context;
 31
 32#if SDL_VERSION_ATLEAST(2, 0, 0)
 33	context->deviceId = SDL_OpenAudioDevice(0, 0, &context->desiredSpec, &context->obtainedSpec, SDL_AUDIO_ALLOW_FREQUENCY_CHANGE);
 34	if (context->deviceId == 0) {
 35#else
 36	if (SDL_OpenAudio(&context->desiredSpec, &context->obtainedSpec) < 0) {
 37#endif
 38		mLOG(SDL_AUDIO, ERROR, "Could not open SDL sound system");
 39		return false;
 40	}
 41	context->samples = context->obtainedSpec.samples;
 42	context->core = 0;
 43
 44	if (threadContext) {
 45		context->core = threadContext->core;
 46		context->sync = &threadContext->sync;
 47
 48#if SDL_VERSION_ATLEAST(2, 0, 0)
 49		SDL_PauseAudioDevice(context->deviceId, 0);
 50#else
 51		SDL_PauseAudio(0);
 52#endif
 53	}
 54
 55	return true;
 56}
 57
 58void mSDLDeinitAudio(struct mSDLAudio* context) {
 59	UNUSED(context);
 60#if SDL_VERSION_ATLEAST(2, 0, 0)
 61	SDL_PauseAudioDevice(context->deviceId, 1);
 62	SDL_CloseAudioDevice(context->deviceId);
 63#else
 64	SDL_PauseAudio(1);
 65	SDL_CloseAudio();
 66#endif
 67	SDL_QuitSubSystem(SDL_INIT_AUDIO);
 68}
 69
 70void mSDLPauseAudio(struct mSDLAudio* context) {
 71#if SDL_VERSION_ATLEAST(2, 0, 0)
 72	SDL_PauseAudioDevice(context->deviceId, 1);
 73#else
 74	UNUSED(context);
 75	SDL_PauseAudio(1);
 76#endif
 77}
 78
 79void mSDLResumeAudio(struct mSDLAudio* context) {
 80#if SDL_VERSION_ATLEAST(2, 0, 0)
 81	SDL_PauseAudioDevice(context->deviceId, 0);
 82#else
 83	UNUSED(context);
 84	SDL_PauseAudio(0);
 85#endif
 86}
 87
 88static void _mSDLAudioCallback(void* context, Uint8* data, int len) {
 89	struct mSDLAudio* audioContext = context;
 90	if (!context || !audioContext->core) {
 91		memset(data, 0, len);
 92		return;
 93	}
 94	blip_t* left = NULL;
 95	blip_t* right = NULL;
 96	int32_t clockRate = GBA_ARM7TDMI_FREQUENCY;
 97	if (audioContext->core) {
 98		left = audioContext->core->getAudioChannel(audioContext->core, 0);
 99		right = audioContext->core->getAudioChannel(audioContext->core, 1);
100		clockRate = audioContext->core->frequency(audioContext->core);
101	}
102	double fauxClock = 1;
103	if (audioContext->sync) {
104		if (audioContext->sync->fpsTarget > 0) {
105			fauxClock = GBAAudioCalculateRatio(1, audioContext->sync->fpsTarget, 1);
106		}
107		mCoreSyncLockAudio(audioContext->sync);
108	}
109	blip_set_rates(left, clockRate, audioContext->obtainedSpec.freq * fauxClock);
110	blip_set_rates(right, clockRate, audioContext->obtainedSpec.freq * fauxClock);
111	len /= 2 * audioContext->obtainedSpec.channels;
112	int available = blip_samples_avail(left);
113	if (available > len) {
114		available = len;
115	}
116	blip_read_samples(left, (short*) data, available, audioContext->obtainedSpec.channels == 2);
117	if (audioContext->obtainedSpec.channels == 2) {
118		blip_read_samples(right, ((short*) data) + 1, available, 1);
119	}
120
121	if (audioContext->sync) {
122		mCoreSyncConsumeAudio(audioContext->sync);
123	}
124	if (available < len) {
125		memset(((short*) data) + audioContext->obtainedSpec.channels * available, 0, (len - available) * audioContext->obtainedSpec.channels * sizeof(short));
126	}
127}