BACKENDS: Switch to a common base class for threaded audio CD streams

backends/audiocd/audiocd-stream.cpp

@@ -0,0 +1,174 @@
+/* Cabal - Legacy Game Implementations
+ *
+ * Cabal 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.
+ *
+ */
+
+#include "backends/audiocd/audiocd-stream.h"
+#include "common/textconsole.h"
+
+AudioCDStream::AudioCDStream() : _buffer(), _frame(0), _bufferPos(0), _bufferFrame(0), _forceStop(false) {
+}
+
+AudioCDStream::~AudioCDStream() {
+	// Stop the timer; the subclass needs to do this,
+	// so this is just a last resort.
+	stopTimer();
+
+	// Clear any buffered frames
+	emptyQueue();
+}
+
+int AudioCDStream::readBuffer(int16 *buffer, const int numSamples) {
+	int samples = 0;
+
+	// See if any data is left first
+	while (_bufferPos < kSamplesPerFrame && samples < numSamples)
+		buffer[samples++] = _buffer[_bufferPos++];
+
+	// Bail out if done
+	if (endOfData())
+		return samples;
+
+	while (samples < numSamples && !endOfData()) {
+		if (!readNextFrame())
+			return samples;
+
+		// Copy the samples over
+		for (_bufferPos = 0; _bufferPos < kSamplesPerFrame && samples < numSamples; )
+			buffer[samples++] = _buffer[_bufferPos++];
+	}
+
+	return samples;
+}
+
+bool AudioCDStream::readNextFrame() {
+	// Fetch a frame from the queue
+	int16 *buffer;
+
+	{
+		Common::StackLock lock(_mutex);
+
+		// Nothing we can do if it's empty
+		if (_bufferQueue.empty())
+			return false;
+
+		buffer = _bufferQueue.pop();
+	}
+
+	memcpy(_buffer, buffer, kSamplesPerFrame * 2);
+	delete[] buffer;
+	_frame++;
+	return true;
+}
+
+bool AudioCDStream::endOfData() const {
+	return !shouldForceStop() && getStartFrame() + _frame >= getEndFrame() && _bufferPos == kSamplesPerFrame;
+}
+
+bool AudioCDStream::seek(const Audio::Timestamp &where) {
+	// Stop the timer
+	stopTimer();
+
+	// Clear anything out of the queue
+	emptyQueue();
+
+	// Convert to the frame number
+	// Really not much else needed
+	_bufferPos = kSamplesPerFrame;
+	_frame = where.convertToFramerate(kFramesPerSecond).totalNumberOfFrames();
+	_bufferFrame = _frame;
+
+	// Start the timer again
+	startTimer();
+	return true;
+}
+
+Audio::Timestamp AudioCDStream::getLength() const {
+	return Audio::Timestamp(0, getEndFrame() - getStartFrame(), kFramesPerSecond);
+}
+
+void AudioCDStream::timerProc(void *refCon) {
+	static_cast<AudioCDStream *>(refCon)->onTimer();
+}
+
+void AudioCDStream::onTimer() {
+	// The goal here is to do as much work in this timer instead
+	// of doing it in the readBuffer() call, which is the mixer.
+
+	// If we're done, bail.
+	if (shouldForceStop() || getStartFrame() + _bufferFrame >= getEndFrame())
+		return;
+
+	// Get a quick count of the number of items in the queue
+	// We don't care that much; we only need a quick estimate
+	_mutex.lock();
+	uint32 queueCount = _bufferQueue.size();
+	_mutex.unlock();
+
+	// If we have enough audio buffered, bail out
+	if (queueCount >= kBufferThreshold)
+		return;
+
+	while (!shouldForceStop() && queueCount < kBufferThreshold && getStartFrame() + _bufferFrame < getEndFrame()) {
+		int16 *buffer = new int16[kSamplesPerFrame];
+
+		// Figure out the MSF of the frame we're looking for
+		int frame = _bufferFrame + getStartFrame();
+
+		// Request to read that frame
+		if (!readFrame(frame, buffer)) {
+			warning("Failed to read CD audio");
+			forceStop();
+			return;
+		}
+
+		_bufferFrame++;
+
+		// Now push the buffer onto the queue
+		Common::StackLock lock(_mutex);
+		_bufferQueue.push(buffer);
+		queueCount = _bufferQueue.size();
+	}
+}
+
+void AudioCDStream::startTimer() {
+	_forceStop = false;
+	g_system->getTimerManager()->installTimerProc(timerProc, 10 * 1000, this, "AudioCDStream");
+}
+
+void AudioCDStream::stopTimer() {
+	forceStop();
+	g_system->getTimerManager()->removeTimerProc(timerProc);
+}
+
+void AudioCDStream::emptyQueue() {
+	while (!_bufferQueue.empty())
+		delete[] _bufferQueue.pop();
+}
+
+bool AudioCDStream::shouldForceStop() const {
+	Common::StackLock lock(_forceStopMutex);
+	return _forceStop;
+}
+
+void AudioCDStream::forceStop() {
+	Common::StackLock lock(_forceStopMutex);
+	_forceStop = true;
+}

backends/audiocd/audiocd-stream.h

@@ -0,0 +1,86 @@
+/* Cabal - Legacy Game Implementations
+ *
+ * Cabal 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.
+ *
+ */
+
+#ifndef BACKENDS_AUDIOCD_AUDIOCD_STREAM_H
+#define BACKENDS_AUDIOCD_AUDIOCD_STREAM_H
+
+#include "audio/audiostream.h"
+#include "common/mutex.h"
+#include "common/queue.h"
+#include "common/timer.h"
+
+class AudioCDStream : public Audio::SeekableAudioStream {
+public:
+	AudioCDStream();
+	~AudioCDStream();
+
+	int readBuffer(int16 *buffer, const int numSamples);
+	bool isStereo() const { return true; }
+	int getRate() const { return 44100; }
+	bool endOfData() const;
+	bool seek(const Audio::Timestamp &where);
+	Audio::Timestamp getLength() const;
+
+protected:
+	virtual uint getStartFrame() const = 0;
+	virtual uint getEndFrame() const = 0;
+	virtual bool readFrame(int frame, int16 *buffer) = 0;
+
+	void startTimer();
+	void stopTimer();
+
+	enum {
+		kBytesPerFrame = 2352,
+		kSamplesPerFrame = kBytesPerFrame / 2
+	};
+
+	enum {
+		kSecondsPerMinute = 60,
+		kFramesPerSecond = 75
+	};
+
+	enum {
+		// Keep about a second's worth of audio in the buffer
+		kBufferThreshold = kFramesPerSecond
+	};
+
+private:
+	int16 _buffer[kSamplesPerFrame];
+	int _frame;
+	uint _bufferPos;
+
+	Common::Queue<int16 *> _bufferQueue;
+	int _bufferFrame;
+        Common::Mutex _mutex;
+
+        bool _forceStop;
+        bool shouldForceStop() const;
+        void forceStop();
+        Common::Mutex _forceStopMutex;
+
+        bool readNextFrame();
+        static void timerProc(void *refCon);
+        void onTimer();
+        void emptyQueue();
+};
+
+#endif