TITANIC: Simplify implementation of CAudioBuffer

4 files changed, 63 insertions, 85 deletions

diff --git a/engines/titanic/sound/audio_buffer.cpp b/engines/titanic/sound/audio_buffer.cpp
index 029e7f0d9c..1f0693181a 100644
--- a/engines/titanic/sound/audio_buffer.cpp
+++ b/engines/titanic/sound/audio_buffer.cpp
@@ -21,62 +21,49 @@
  */
 
 #include "titanic/sound/audio_buffer.h"
+#include "common/algorithm.h"
 
 namespace Titanic {
 
-CAudioBuffer::CAudioBuffer(int bufferSize) : _flag(true), _disabled(false) {
-	_buffer.resize(bufferSize);
-	reset();
-}
-
-CAudioBuffer::~CAudioBuffer() {
-	_buffer.clear();
+CAudioBuffer::CAudioBuffer(int maxSize) : _finished(false) {
+	_data.resize(maxSize);
 }
 
 void CAudioBuffer::reset() {
-	_flag = true;
-	_readBytesLeft = _writeBytesLeft = _buffer.size() / 2;
+	_frontP = _backP = &_data[0];
 }
 
-byte *CAudioBuffer::getBegin() {
-	return _flag ? &_buffer[_buffer.size() / 2] : &_buffer[0];
-}
+void CAudioBuffer::push(int16 value) {
+	assert(!full());
+	compact();
 
-byte *CAudioBuffer::getEnd() {
-	return _flag ? &_buffer[0] : &_buffer[_buffer.size() / 2];
+	*_backP++ = value;
 }
 
-int16 *CAudioBuffer::getReadPtr() {
-	byte *ptr = getBegin();
-	return (int16 *)(ptr + (_buffer.size() / 2 - _readBytesLeft));
-}
+void CAudioBuffer::push(int16 *values, int count) {
+	compact();
+	assert(freeSize() >= count);
 
-int16 *CAudioBuffer::getWritePtr() {
-	byte *ptr = getEnd();
-	return (int16 *)(ptr + (_buffer.size() / 2 - _writeBytesLeft));
+	Common::copy(values, values + count, _backP);
+	_backP += count;
 }
 
-void CAudioBuffer::advanceRead(int size) {
-	_readBytesLeft -= size;
-	if (_readBytesLeft < 0) {
-		_readBytesLeft = 0;
-	} else if (size && !_writeBytesLeft) {
-		reverse();
-	}
+int16 CAudioBuffer::pop() {
+	assert(!empty());
+	return *_frontP++;
 }
 
-void CAudioBuffer::advanceWrite(int size) {
-	_writeBytesLeft -= size;
-	if (_writeBytesLeft < 0) {
-		_writeBytesLeft = 0;
-	} else if (size && !_readBytesLeft) {
-		reverse();
+void CAudioBuffer::compact() {
+	if (_frontP != &_data[0]) {
+		Common::copy(_frontP, _backP, &_data[0]);
+		_backP -= _frontP - &_data[0];
+		_frontP = &_data[0];
 	}
 }
 
-void CAudioBuffer::reverse() {
-	_flag = !_flag;
-	_readBytesLeft = _writeBytesLeft = _buffer.size() / 2;
+int CAudioBuffer::freeSize() {
+	compact();
+	return &_data[0] + _data.size() - _backP;
 }
 
 void CAudioBuffer::enterCriticalSection() {
diff --git a/engines/titanic/sound/audio_buffer.h b/engines/titanic/sound/audio_buffer.h
index 54dd807250..8d27667e93 100644
--- a/engines/titanic/sound/audio_buffer.h
+++ b/engines/titanic/sound/audio_buffer.h
@@ -31,30 +31,18 @@ namespace Titanic {
 class CAudioBuffer {
 private:
 	Common::Mutex _mutex;
-private:
-	/**
-	 * Gets the beginning of stored audio data
-	 */
-	byte *getBegin();
-
-	/**
-	 * Gets the end of the stored audio data
-	 */
-	byte *getEnd();
+	Common::Array<int16> _data;
+	int16 *_frontP, *_backP;
 
 	/**
-	 * Reverses the audio buffer
+	 * Reclaims any space at the start of the array resulting from
+	 * having read values off the font
 	 */
-	void reverse();
+	void compact();
 public:
-	Common::Array<byte> _buffer;
-	int _readBytesLeft;
-	int _writeBytesLeft;
-	bool _flag;
-	bool _disabled;
+	bool _finished;
 public:
-	CAudioBuffer(int bufferSize);
-	~CAudioBuffer();
+	CAudioBuffer(int maxSize);
 
 	/**
 	 * Resets the audio buffer
@@ -62,36 +50,39 @@ public:
 	void reset();
 
 	/**
-	 * Gets a pointer to the start of previously written data
+	 * Returns true if the buffer is empty
 	 */
-	int16 *getReadPtr();
+	bool empty() const { return _data.empty(); }
 
 	/**
-	 * Returns the number of bytes that can be read
+	 * Returns the number of 16-bit entries in the buffer
 	 */
-	int getBytesToRead() const { return _readBytesLeft; }
+	int size() const { return _backP - _frontP; }
 
 	/**
-	 * Advances the read index
+	 * Returns true if the buffer is full
 	 */
-	void advanceRead(int size);
+	bool full() const { return (_backP - _frontP) == (int)_data.size(); }
 
 	/**
-	 * Gets a pointer to the remainder of the audio buffer that
-	 * can be written to
+	 * Returns the number of entries free in the buffer
 	 */
-	int16 *getWritePtr();
+	int freeSize();
 
 	/**
-	 * Returns how many bytes can be written before hitting the
-	 * end of the audio buffer
+	 * Adds a value to the buffer
 	 */
-	int getWriteBytesLeft() const { return _writeBytesLeft; }
-	
+	void push(int16 value);
+
+	/**
+	 * Adds a value to the buffer
+	 */
+	void push(int16 *values, int count);
+
 	/**
-	 * Advances the write pointer by the specified number of bytes
+	 * Removes a value from the buffer
 	 */
-	void advanceWrite(int size);
+	int16 pop();
 
 	/**
 	 * Enters a critical section
diff --git a/engines/titanic/sound/music_room_handler.cpp b/engines/titanic/sound/music_room_handler.cpp
index e50384e0f8..d464a1d95d 100644
--- a/engines/titanic/sound/music_room_handler.cpp
+++ b/engines/titanic/sound/music_room_handler.cpp
@@ -40,7 +40,7 @@ CMusicRoomHandler::CMusicRoomHandler(CProjectItem *project, CSoundManager *sound
 	Common::fill(&_array5[0], &_array5[4], 0.0);
 	Common::fill(&_position[0], &_position[4], 0);
 
-	_audioBuffer = new CAudioBuffer(176400);
+	_audioBuffer = new CAudioBuffer(88200);
 }
 
 CMusicRoomHandler::~CMusicRoomHandler() {
@@ -96,7 +96,6 @@ void CMusicRoomHandler::setup(int volume) {
 	update();
 
 	_waveFile = _soundManager->loadMusic(_audioBuffer, DisposeAfterUse::NO);
-	_audioBuffer->advanceRead(_audioBuffer->getBytesToRead());
 	update();
 }
 
@@ -203,14 +202,15 @@ bool CMusicRoomHandler::update() {
 
 void CMusicRoomHandler::updateAudio() {
 	_audioBuffer->enterCriticalSection();
-	int size = _audioBuffer->getWriteBytesLeft();
+
+	int size = _audioBuffer->freeSize();
 	int count;
 	int16 *ptr;
 
 	if (size > 0) {
-		// Null out the destination write area
-		int16 *audioPtr = _audioBuffer->getWritePtr();
-		Common::fill(audioPtr, audioPtr + size / sizeof(uint16), 0);
+		// Create a temporary buffer for merging the instruments into
+		int16 *audioData = new int16[size];
+		Common::fill(audioData, audioData + size, 0);
 
 		for (MusicInstrument instrument = BELLS; instrument <= BASS;
 				instrument = (MusicInstrument)((int)instrument + 1)) {
@@ -218,7 +218,7 @@ void CMusicRoomHandler::updateAudio() {
 
 			// Iterate through each of the four instruments and do an additive
 			// read that will merge their data onto the output buffer
-			for (count = size, ptr = audioPtr; count > 0; ) {
+			for (count = size, ptr = audioData; count > 0; ) {
 				int amount = musicWave->read(ptr, count);
 				if (amount > 0) {
 					count -= amount;
@@ -230,7 +230,8 @@ void CMusicRoomHandler::updateAudio() {
 			}
 		}
 		
-		_audioBuffer->advanceWrite(size);
+		_audioBuffer->push(audioData, size);
+		delete[] audioData;
 	}
 
 	_audioBuffer->leaveCriticalSection();
diff --git a/engines/titanic/sound/wave_file.cpp b/engines/titanic/sound/wave_file.cpp
index a4cd9d3e3f..b094adbafe 100644
--- a/engines/titanic/sound/wave_file.cpp
+++ b/engines/titanic/sound/wave_file.cpp
@@ -49,18 +49,17 @@ public:
 
 int AudioBufferStream::readBuffer(int16 *buffer, const int numSamples) {
 	_audioBuffer->enterCriticalSection();
-	int samplesToRead = MIN((const int)numSamples, (const int)(_audioBuffer->getBytesToRead() / sizeof(uint16)));
-	
-	const int16 *src = _audioBuffer->getReadPtr();
-	Common::copy(src, src + samplesToRead, buffer);
-	_audioBuffer->advanceRead(samplesToRead * 2);
+	int samplesToRead = MIN((const int)numSamples, (const int)_audioBuffer->size());
+
+	for (int idx = 0; idx < samplesToRead; ++idx)
+		*buffer++ = _audioBuffer->pop();
 
 	_audioBuffer->leaveCriticalSection();
 	return samplesToRead;
 }
 
 bool AudioBufferStream::endOfData() const {
-	return _audioBuffer->_disabled;
+	return _audioBuffer->_finished;
 }
 
 /*------------------------------------------------------------------------*/