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/* REminiscence - Flashback interpreter
* Copyright (C) 2005-2011 Gregory Montoir
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "mixer.h"
#include "systemstub.h"
Mixer::Mixer(SystemStub *stub)
: _stub(stub) {
}
void Mixer::init() {
memset(_channels, 0, sizeof(_channels));
_premixHook = 0;
_stub->startAudio(Mixer::mixCallback, this);
}
void Mixer::free() {
stopAll();
_stub->stopAudio();
}
void Mixer::setPremixHook(PremixHook premixHook, void *userData) {
debug(DBG_SND, "Mixer::setPremixHook()");
LockAudioStack las(_stub);
_premixHook = premixHook;
_premixHookData = userData;
}
void Mixer::play(const MixerChunk *mc, uint16 freq, uint8 volume) {
debug(DBG_SND, "Mixer::play(%d, %d)", freq, volume);
LockAudioStack las(_stub);
MixerChannel *ch = 0;
for (int i = 0; i < NUM_CHANNELS; ++i) {
MixerChannel *cur = &_channels[i];
if (cur->active) {
if (cur->chunk.data == mc->data) {
cur->chunkPos = 0;
return;
}
} else {
ch = cur;
break;
}
}
if (ch) {
ch->active = true;
ch->volume = volume;
ch->chunk = *mc;
ch->chunkPos = 0;
ch->chunkInc = (freq << FRAC_BITS) / _stub->getOutputSampleRate();
}
}
uint32 Mixer::getSampleRate() const {
return _stub->getOutputSampleRate();
}
void Mixer::stopAll() {
debug(DBG_SND, "Mixer::stopAll()");
LockAudioStack las(_stub);
for (uint8 i = 0; i < NUM_CHANNELS; ++i) {
_channels[i].active = false;
}
}
void Mixer::mix(int8 *buf, int len) {
memset(buf, 0, len);
if (_premixHook) {
if (!_premixHook(_premixHookData, buf, len)) {
_premixHook = 0;
_premixHookData = 0;
}
}
for (uint8 i = 0; i < NUM_CHANNELS; ++i) {
MixerChannel *ch = &_channels[i];
if (ch->active) {
for (int pos = 0; pos < len; ++pos) {
if ((ch->chunkPos >> FRAC_BITS) >= (ch->chunk.len - 1)) {
ch->active = false;
break;
}
int out = resampleLinear(&ch->chunk, ch->chunkPos, ch->chunkInc, FRAC_BITS);
addclamp(buf[pos], out * ch->volume / Mixer::MAX_VOLUME);
ch->chunkPos += ch->chunkInc;
}
}
}
}
void Mixer::addclamp(int8& a, int b) {
int add = a + b;
if (add < -128) {
add = -128;
} else if (add > 127) {
add = 127;
}
a = add;
}
void Mixer::mixCallback(void *param, uint8 *buf, int len) {
((Mixer *)param)->mix((int8 *)buf, len);
}
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