// A C version of mix_mmx
// mix_mmx is 2.5 times as fast on Pentium 4
// NOTE : we always want this defined, even when using MMX, for the purpose of
// testing (see releasetest)
void mix_c()
{
unsigned int uSamplesToMix = g_uBytesToMix >> 1;
Uint8 *stream = g_pSampleDst;
unsigned int sample = 0, val_to_store = 0;
for (sample = 0; sample < uSamplesToMix; sample += 2) {
int mixed_sample_1 = 0, mixed_sample_2 = 0; // left/right channels
struct mix_s *cur = g_pMixBufs;
// mix all sound chips
while (cur) {
mixed_sample_1 += LOAD_LIL_SINT16(((short *)cur->pMixBuf) + sample);
mixed_sample_2 += LOAD_LIL_SINT16(((short *)cur->pMixBuf) + sample + 1);
cur = cur->pNext;
}
DO_CLIP(mixed_sample_1);
DO_CLIP(mixed_sample_2);
// note: sample2 needs to be on top because this is little endian, hence
// LSB
val_to_store = (((unsigned short)mixed_sample_2) << 16) |
((unsigned short)mixed_sample_1);
STORE_LIL_UINT32(stream, val_to_store);
stream += 4;
}
}
// called from sound mixer to get audio stream
void samples_get_stream(Uint8 *stream, int length, int unused)
{
#ifdef DEBUG
assert (length % 4 == 0); // make sure it's divisible by 4
#endif
// (each sample is 4 bytes, which is why we divide length by 4)
unsigned int uTotalSamples = length >> 2;
// clear buffer so that our addition will work
memset(stream, 0, length);
unsigned int u = 0;
// check to see if any sample is playing ...
for (u = 0; u < MAX_DYNAMIC_SAMPLES; ++u)
{
sample_data_s *data = &g_SampleStates[u];
if (data->bActive)
{
Uint8 *ptrStream = stream;
// do each sample
for (unsigned int uSample = 0; uSample < uTotalSamples; ++uSample)
{
// if there is still some sample data to be mixed to this stream
if (data->uPos < data->uLength)
{
int iMixedSample1 = LOAD_LIL_SINT16((Sint16 *) ptrStream);
int iMixedSample2 = LOAD_LIL_SINT16(((Sint16 *) ptrStream) + 1);
Sint16 i16Sample1 = LOAD_LIL_SINT16(data->pu8Buf + data->uPos);
iMixedSample1 += i16Sample1;
data->uPos += 2;
// if this is a stereo sample
if (data->uChannels == 2)
{
iMixedSample2 += LOAD_LIL_SINT16(data->pu8Buf + data->uPos);
data->uPos += 2;
}
// else this is a mono sample, so just duplicate the last sample we read in
else
{
iMixedSample2 += i16Sample1;
}
DO_CLIP(iMixedSample1); // prevent overflow
DO_CLIP(iMixedSample2);
// yes, sample2 should be the most significant, sample1 least significant.. releasetest tests this
unsigned int val_to_store = (((Uint16) iMixedSample2) << 16) | (Uint16) iMixedSample1;
STORE_LIL_UINT32(ptrStream, val_to_store);
ptrStream += 4;
}
// else this sample is done, so get rid of the entry ...
else
{
data->bActive = false;
// if caller has requested to be notified when this sample is done ...
if (data->finishedCallback != NULL)
{
data->finishedCallback(data->pu8Buf, u);
}
break;
}
} // end going through stream buffer
} // end while we have states to be addressed
} // end looping through all sample slots
}
