1 files changed, 129 insertions, 0 deletions
diff --git a/backends/mixer/doublebuffersdl/doublebuffersdl-mixer.cpp b/backends/mixer/doublebuffersdl/doublebuffersdl-mixer.cpp
new file mode 100644
index 0000000000..6b0074862e
--- /dev/null
+++ b/backends/mixer/doublebuffersdl/doublebuffersdl-mixer.cpp
@@ -0,0 +1,129 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#if defined(MACOSX) || defined(GP2X)
+
+#include "backends/mixer/doublebuffersdl/doublebuffersdl-mixer.h"
+
+DoubleBufferSDLMixerManager::DoubleBufferSDLMixerManager()
+	:
+	_soundMutex(0), _soundCond(0), _soundThread(0),
+	_soundThreadIsRunning(false), _soundThreadShouldQuit(false) {
+	
+}
+
+DoubleBufferSDLMixerManager::~DoubleBufferSDLMixerManager() {
+	deinitThreadedMixer();
+}
+
+void DoubleBufferSDLMixerManager::startAudio() {
+	_soundThreadIsRunning = false;
+	_soundThreadShouldQuit = false;
+
+	// Create mutex and condition variable
+	_soundMutex = SDL_CreateMutex();
+	_soundCond = SDL_CreateCond();
+
+	// Create two sound buffers
+	_activeSoundBuf = 0;
+	uint bufSize = _obtainedRate.samples * 4;
+	_soundBufSize = bufSize;
+	_soundBuffers[0] = (byte *)calloc(1, bufSize);
+	_soundBuffers[1] = (byte *)calloc(1, bufSize);
+
+	_soundThreadIsRunning = true;
+
+	// Finally start the thread
+	_soundThread = SDL_CreateThread(mixerProducerThreadEntry, this);
+
+	SdlMixerManager::startAudio();
+}
+
+void DoubleBufferSDLMixerManager::mixerProducerThread() {
+	byte nextSoundBuffer;
+
+	SDL_LockMutex(_soundMutex);
+	while (true) {
+		// Wait till we are allowed to produce data
+		SDL_CondWait(_soundCond, _soundMutex);
+
+		if (_soundThreadShouldQuit)
+			break;
+
+		// Generate samples and put them into the next buffer
+		nextSoundBuffer = _activeSoundBuf ^ 1;
+		_mixer->mixCallback(_soundBuffers[nextSoundBuffer], _soundBufSize);
+
+		// Swap buffers
+		_activeSoundBuf = nextSoundBuffer;
+	}
+	SDL_UnlockMutex(_soundMutex);
+}
+
+int SDLCALL DoubleBufferSDLMixerManager::mixerProducerThreadEntry(void *arg) {
+	DoubleBufferSDLMixerManager *mixer = (DoubleBufferSDLMixerManager *)arg;
+	assert(mixer);
+	mixer->mixerProducerThread();
+	return 0;
+}
+
+void DoubleBufferSDLMixerManager::deinitThreadedMixer() {
+	// Kill thread?? _soundThread
+
+	if (_soundThreadIsRunning) {
+		// Signal the producer thread to end, and wait for it to actually finish.
+		_soundThreadShouldQuit = true;
+		SDL_CondBroadcast(_soundCond);
+		SDL_WaitThread(_soundThread, NULL);
+
+		// Kill the mutex & cond variables.
+		// Attention: AT this point, the mixer callback must not be running
+		// anymore, else we will crash!
+		SDL_DestroyMutex(_soundMutex);
+		SDL_DestroyCond(_soundCond);
+
+		_soundThreadIsRunning = false;
+
+		free(_soundBuffers[0]);
+		free(_soundBuffers[1]);
+	}
+}
+
+void DoubleBufferSDLMixerManager::callbackHandler(byte *samples, int len) {
+	assert(_mixer);
+	assert((int)_soundBufSize == len);
+
+	// Lock mutex, to ensure our data is not overwritten by the producer thread
+	SDL_LockMutex(_soundMutex);
+
+	// Copy data from the current sound buffer
+	memcpy(samples, _soundBuffers[_activeSoundBuf], len);
+
+	// Unlock mutex and wake up the produced thread
+	SDL_UnlockMutex(_soundMutex);
+	SDL_CondSignal(_soundCond);
+}
+
+#endif