mixer_soft.cpp

/*
 * Bermuda Syndrome engine rewrite
 * Copyright (C) 2007-2011 Gregory Montoir
 */

#include "file.h"
#include "mixer.h"
#include "systemstub.h"
#ifdef BERMUDA_VORBIS
#include <vorbis/vorbisfile.h>
#endif

static const int _fracStepBits = 8;
static const int _sfxVolume = 256;
static const int _musicVolume = 192;

struct LockAudioStack {
	LockAudioStack(SystemStub *stub) : _stub(stub) {
		_stub->lockAudio();
	}
	~LockAudioStack() {
		_stub->unlockAudio();
	}
	SystemStub *_stub;
};

static void mixSample(int16_t &dst, int sample, int volume) {
	int pcm = dst + ((sample * volume) >> 8);
	if (pcm < -32768) {
		pcm = -32768;
	} else if (pcm > 32767) {
		pcm = 32767;
	}
	dst = (int16_t)pcm;
}

struct MixerChannel {
	virtual ~MixerChannel() {}
	virtual bool load(File *f, int mixerSampleRate) = 0;
	virtual int read(int16_t *dst, int samples) = 0;
	int id;
};

struct MixerChannel_Wav : MixerChannel {
	MixerChannel_Wav()
		: _buf(0), _bufSize(0), _bufReadOffset(0), _bufReadStep(0) {
	}

	virtual ~MixerChannel_Wav() {
		if (_buf) {
			free(_buf);
			_buf = 0;
		}
	}

	virtual bool load(File *f, int mixerSampleRate) {
		char buf[8];
		f->seek(8); // skip RIFF header
		f->read(buf, 8);
		if (memcmp(buf, "WAVEfmt ", 8) == 0) {
			f->readUint32LE(); // fmtLength
			int compression = f->readUint16LE();
			int channels = f->readUint16LE();
			int sampleRate = f->readUint32LE();
			f->readUint32LE(); // averageBytesPerSec
			f->readUint16LE(); // blockAlign
			_bitsPerSample = f->readUint16LE();
			if (compression != 1 ||
			    (channels != 1 && channels != 2) ||
			    (sampleRate != 11025 && sampleRate != 22050 && sampleRate != 44100) ||
			    (_bitsPerSample != 8 && _bitsPerSample != 16)) {
				warning("Unhandled wav/pcm format compression %d channels %d rate %d bits %d", compression, channels, sampleRate, _bitsPerSample);
				return false;
			}
			_stereo = (channels == 2);
			_bufReadStep = (sampleRate << _fracStepBits) / mixerSampleRate;
			f->read(buf, 4);
			if (memcmp(buf, "data", 4) == 0) {
				_bufSize = f->readUint32LE();
				_buf = (uint8_t *)malloc(_bufSize);
				if (_buf) {
					f->read(_buf, _bufSize);
					return true;
				}
			}
		}
		return false;
	}

	bool readSample(int16_t &sample) {
		switch (_bitsPerSample) {
		case 8:
			if ((_bufReadOffset >> _fracStepBits) >= _bufSize) { // end of buffer
				return false;
			}
			sample = (_buf[_bufReadOffset >> _fracStepBits] << 8) ^ 0x8000;
			break;
		case 16:
			if ((_bufReadOffset >> _fracStepBits) * 2 >= _bufSize) { // end of buffer
				return false;
			}
			sample = READ_LE_UINT16(&_buf[(_bufReadOffset >> _fracStepBits) * 2]);
			break;
		}
		_bufReadOffset += _bufReadStep;
		return true;
	}

	virtual int read(int16_t *dst, int samples) {
		for (int i = 0; i < samples; ++i) {
			int16_t sampleL = 0, sampleR;
			if (!readSample(sampleL)) {
				return i;
			}
			sampleR = sampleL;
			if (_stereo && !readSample(sampleR)) {
				return i;
			}
			mixSample(*dst++, sampleL, _sfxVolume);
			mixSample(*dst++, sampleR, _sfxVolume);
		}
		return samples;
	}

	uint8_t *_buf;
	int _bufSize;
	int _bufReadOffset;
	int _bufReadStep;
	int _bitsPerSample;
	bool _stereo;
};

#ifdef BERMUDA_VORBIS
static size_t file_vorbis_read_helper(void *ptr, size_t size, size_t nmemb, void *datasource) {
	if (size != 0 && nmemb != 0) {
		int n = ((File *)datasource)->read(ptr, size * nmemb);
		if (n > 0) {
			return n / size;
		}
	}
	return 0;
}

static int file_vorbis_seek_helper(void *datasource, ogg_int64_t offset, int whence) {
	((File *)datasource)->seek(offset, whence);
	return 0;
}

static int file_vorbis_close_helper(void *datasource) {
	((File *)datasource)->close();
	delete ((File *)datasource);
	return 0;
}

static long file_vorbis_tell_helper(void *datasource) {
	return ((File *)datasource)->tell();
}

struct MixerChannel_Vorbis : MixerChannel {
	MixerChannel_Vorbis()
		: _loop(true), _open(false), _readBuf(0), _readBufSize(0) {
	}

	virtual ~MixerChannel_Vorbis() {
		if (_open) {
			ov_clear(&_ovf);
		}
		free(_readBuf);
	}

	virtual bool load(File *f, int mixerSampleRate) {
		ov_callbacks ovcb;
		ovcb.read_func  = file_vorbis_read_helper;
		ovcb.seek_func  = file_vorbis_seek_helper;
		ovcb.close_func = file_vorbis_close_helper;
		ovcb.tell_func  = file_vorbis_tell_helper;
		if (ov_open_callbacks(f, &_ovf, 0, 0, ovcb) < 0) {
			warning("Invalid .ogg file");
			return false;
		}
		_open = true;
		vorbis_info *vi = ov_info(&_ovf, -1);
		if (vi->channels != 2 || vi->rate != mixerSampleRate) {
			warning("Unhandled ogg/pcm format ch %d rate %d", vi->channels, vi->rate);
			return false;
		}
		return true;
	}

	virtual int read(int16_t *dst, int samples) {
		int dstSize = samples * sizeof(int16_t) * 2;
		if (dstSize > _readBufSize) {
			_readBufSize = dstSize;
			free(_readBuf);
			_readBuf = (char *)malloc(_readBufSize);
			if (!_readBuf) {
				return 0;
			}
		}
		int readSize = 0;
		while (dstSize > 0) {
			int len = ov_read(&_ovf, _readBuf, dstSize, 0, 2, 1, 0);
			if (len < 0) {
				// error in decoder
				return 0;
			}
			if (len == 0) {
				if (_loop) {
					ov_raw_seek(&_ovf, 0);
					continue;
				}
				break;
			}
			// mix pcm data
			for (unsigned int i = 0; i < len / sizeof(int16_t); ++i) {
				const int16_t sample = (int16_t)READ_LE_UINT16(&_readBuf[i * 2]);
				mixSample(dst[readSize + i], sample, _musicVolume);
			}
			readSize += len / sizeof(int16_t);
			dstSize -= len;
		}
		return readSize;
	}

	OggVorbis_File _ovf;
	bool _loop;
	bool _open;
	char *_readBuf;
	int _readBufSize;
};
#endif

struct MixerSoftware: Mixer {
	static const int kMaxChannels = 4;

	SystemStub *_stub;
	int _channelIdSeed;
	bool _open;
	MixerChannel *_channels[kMaxChannels];

	MixerSoftware(SystemStub *stub)
		: _stub(stub), _channelIdSeed(0), _open(false) {
		memset(_channels, 0, sizeof(_channels));
	}

	virtual ~MixerSoftware() {
		for (int i = 0; i < kMaxChannels; ++i) {
			if (_channels[i]) {
				delete _channels[i];
			}
		}
	}

	virtual void open() {
		if (!_open) {
			_stub->startAudio(MixerSoftware::mixCallback, this);
			_open = true;
		}
	}

	virtual void close() {
		if (_open) {
			_stub->stopAudio();
			_open = false;
		}
	}

	void startSound(File *f, int *id, MixerChannel *mc) {
		if (mc->load(f, _stub->getOutputSampleRate()) && bindChannel(mc, id)) {
			return;
		}
		*id = kDefaultSoundId;
		delete mc;
	}

	virtual void playSound(File *f, int *id) {
		debug(DBG_MIXER, "Mixer::playSound()");
		LockAudioStack las(_stub);
		startSound(f, id, new MixerChannel_Wav);
	}

	virtual void playMusic(File *f, int *id) {
		debug(DBG_MIXER, "Mixer::playMusic()");
#ifdef BERMUDA_VORBIS
		LockAudioStack las(_stub);
		startSound(f, id, new MixerChannel_Vorbis);
#endif
	}

	virtual bool isSoundPlaying(int id) {
		debug(DBG_MIXER, "Mixer::isSoundPlaying() 0x%X", id);
		if (id == kDefaultSoundId) {
			return false;
		}
		LockAudioStack las(_stub);
		const int channel = getChannelFromSoundId(id);
		assert(channel >= 0 && channel < kMaxChannels);
		MixerChannel *mc = _channels[channel];
		return (mc && mc->id == id);
	}

	virtual void stopSound(int id) {
		debug(DBG_MIXER, "Mixer::stopSound() 0x%X", id);
		if (id == kDefaultSoundId) {
			return;
		}
		LockAudioStack las(_stub);
		const int channel = getChannelFromSoundId(id);
		assert(channel >= 0 && channel < kMaxChannels);
		MixerChannel *mc = _channels[channel];
		if (mc && mc->id == id) {
			delete mc;
			_channels[channel] = 0;
		}
	}

	virtual void stopAll() {
		debug(DBG_MIXER, "Mixer::stopAll()");
		LockAudioStack las(_stub);
		for (int i = 0; i < kMaxChannels; ++i) {
			if (_channels[i]) {
				delete _channels[i];
				_channels[i] = 0;
			}
		}
	}

	virtual void setMusicMix(void *param, void (*mix)(void *, uint8_t *, int)) {
		if (mix) {
			_stub->startAudio(mix, param);
		} else {
			_stub->startAudio(mixCallback, this);
		}
	}

	void mix(int16_t *buf, int len) {
		assert((len & 1) == 0);
		memset(buf, 0, len * sizeof(int16_t));
		for (int i = 0; i < kMaxChannels; ++i) {
			MixerChannel *mc = _channels[i];
			if (mc) {
				if (mc->read(buf, len / 2) <= 0) {
					delete mc;
					_channels[i] = 0;
				}
			}
		}
	}

	static void mixCallback(void *param, uint8_t *buf, int len) {
		assert((len & 1) == 0);
		((MixerSoftware *)param)->mix((int16_t *)buf, len / 2);
	}

	int generateSoundId(int channel) {
		++_channelIdSeed;
		_channelIdSeed &= 0xFFFF;
		assert(channel >= 0 && channel < 16);
		return (_channelIdSeed << 4) | channel;
	}

	int getChannelFromSoundId(int id) {
		return id & 15;
	}

	bool bindChannel(MixerChannel *mc, int *id) {
		for (int i = 0; i < kMaxChannels; ++i) {
			if (!_channels[i]) {
				_channels[i] = mc;
				*id = mc->id = generateSoundId(i);
				return true;
			}
		}
		return false;
	}

	void unbindChannel(int channel) {
		assert(channel >= 0 && channel < kMaxChannels);
		if (_channels[channel]) {
			delete _channels[channel];
			_channels[channel] = 0;
		}
	}
};

Mixer *Mixer_Software_create(SystemStub *stub) {
	return new MixerSoftware(stub);
}