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/* 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.
*
* $URL$
* $Id$
*
*/
#include "sound/mods/paula.h"
namespace Audio {
Paula::Paula(bool stereo, int rate, int interruptFreq) :
_stereo(stereo), _rate(rate), _intFreq(interruptFreq) {
clearVoices();
_voice[0].panning = 63;
_voice[1].panning = 191;
_voice[2].panning = 191;
_voice[3].panning = 63;
if (_intFreq <= 0)
_intFreq = _rate;
_curInt = _intFreq;
_playing = false;
_end = true;
}
Paula::~Paula() {
}
void Paula::clearVoice(byte voice) {
assert(voice < NUM_VOICES);
_voice[voice].data = 0;
_voice[voice].dataRepeat = 0;
_voice[voice].length = 0;
_voice[voice].lengthRepeat = 0;
_voice[voice].period = 0;
_voice[voice].volume = 0;
_voice[voice].offset = 0;
}
int Paula::readBuffer(int16 *buffer, const int numSamples) {
Common::StackLock lock(_mutex);
memset(buffer, 0, numSamples * 2);
if (!_playing) {
return numSamples;
}
if (_stereo)
return readBufferIntern<true>(buffer, numSamples);
else
return readBufferIntern<false>(buffer, numSamples);
}
template<bool stereo>
inline void mixBuffer(int16 *&buf, const int8 *data, double &offset, double rate, int end, byte volume, byte panning) {
for (int i = 0; i < end; i++) {
// FIXME: We should avoid using floating point arithmetic here, since
// FP calculations and int<->FP conversions are very expensive on many
// architectures.
// So consider replacing offset and rate with fixed point values...
const int32 tmp = ((int32) data[(int)offset]) * volume;
if (stereo) {
*buf++ += (tmp * (255 - panning)) >> 7;
*buf++ += (tmp * (panning)) >> 7;
} else
*buf++ += tmp;
offset += rate;
}
}
template<bool stereo>
int Paula::readBufferIntern(int16 *buffer, const int numSamples) {
int voice;
int samples;
int nSamples;
samples = _stereo ? numSamples / 2 : numSamples;
while (samples > 0) {
if (_curInt == _intFreq) {
interrupt();
_curInt = 0;
}
nSamples = MIN(samples, _intFreq - _curInt);
for (voice = 0; voice < NUM_VOICES; voice++) {
if (!_voice[voice].data || (_voice[voice].period <= 0))
continue;
double frequency = (7093789.2 / 2.0) / _voice[voice].period;
double rate = frequency / _rate;
double offset = _voice[voice].offset;
int sLen = _voice[voice].length;
const int8 *data = _voice[voice].data;
int16 *p = buffer;
int end = 0;
_voice[voice].volume = MIN((byte) 0x40, _voice[voice].volume);
// If looping has been enabled and we see that we will have to loop
// to generate enough samples, then use the "loop" branch.
if ((_voice[voice].lengthRepeat > 2) &&
((int)(offset + nSamples * rate) >= sLen)) {
int neededSamples = nSamples;
while (neededSamples > 0) {
end = MIN(neededSamples, (int)((sLen - offset) / rate));
if (end == 0) {
// This means that "rate" is too high, bigger than the sample size.
// So we scale it down according to the euclidean algorithm.
while (rate > (sLen - offset))
rate -= (sLen - offset);
end = MIN(neededSamples, (int)((sLen - offset) / rate));
}
mixBuffer<stereo>(p, data, offset, rate, end, _voice[voice].volume, _voice[voice].panning);
_voice[voice].offset = offset;
neededSamples -= end;
// If we read beyond the sample end, loop back to the start.
if (ceil(_voice[voice].offset) >= sLen) {
_voice[voice].data = data = _voice[voice].dataRepeat;
_voice[voice].length = sLen = _voice[voice].lengthRepeat;
_voice[voice].offset = offset = 0;
}
}
} else {
if (offset < sLen) { // Sample data left?
end = MIN(nSamples, (int)((sLen - offset) / rate));
mixBuffer<stereo>(p, data, offset, rate, end, _voice[voice].volume, _voice[voice].panning);
_voice[voice].offset = offset;
}
}
}
buffer += _stereo ? nSamples * 2 : nSamples;
_curInt += nSamples;
samples -= nSamples;
}
return numSamples;
}
} // End of namespace Audio
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