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mlpdec: Simplify filtering code by using only one counter variable.

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Originally committed as revision 18695 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Ramiro Polla 2009-04-26 20:37:40 +00:00
parent 60294c593e
commit 77b12f809b
1 changed files with 12 additions and 13 deletions
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25
libavcodec/mlpdec.c
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@ -700,17 +700,18 @@ static void filter_channel(MLPDecodeContext *m, unsigned int substr,
unsigned int channel)
{
SubStream *s = &m->substream[substr];
int32_t firbuf[MAX_BLOCKSIZE + MAX_FIR_ORDER];
int32_t iirbuf[MAX_BLOCKSIZE + MAX_IIR_ORDER];
int32_t fir_state_buffer[MAX_BLOCKSIZE + MAX_FIR_ORDER];
int32_t iir_state_buffer[MAX_BLOCKSIZE + MAX_IIR_ORDER];
int32_t *firbuf = fir_state_buffer + MAX_BLOCKSIZE;
int32_t *iirbuf = iir_state_buffer + MAX_BLOCKSIZE;
FilterParams *fir = &m->channel_params[channel].filter_params[FIR];
FilterParams *iir = &m->channel_params[channel].filter_params[IIR];
unsigned int filter_shift = fir->shift;
int32_t mask = MSB_MASK(s->quant_step_size[channel]);
int index = MAX_BLOCKSIZE;
int i;
memcpy(&firbuf[index], fir->state, MAX_FIR_ORDER * sizeof(int32_t));
memcpy(&iirbuf[index], iir->state, MAX_IIR_ORDER * sizeof(int32_t));
memcpy(firbuf, fir->state, MAX_FIR_ORDER * sizeof(int32_t));
memcpy(iirbuf, iir->state, MAX_IIR_ORDER * sizeof(int32_t));
for (i = 0; i < s->blocksize; i++) {
int32_t residual = m->sample_buffer[i + s->blockpos][channel];
@ -721,23 +722,21 @@ static void filter_channel(MLPDecodeContext *m, unsigned int substr,
/* TODO: Move this code to DSPContext? */
for (order = 0; order < fir->order; order++)
accum += (int64_t) firbuf[index + order] * fir->coeff[order];
accum += (int64_t) firbuf[order] * fir->coeff[order];
for (order = 0; order < iir->order; order++)
accum += (int64_t) iirbuf[index + order] * iir->coeff[order];
accum += (int64_t) iirbuf[order] * iir->coeff[order];
accum = accum >> filter_shift;
result = (accum + residual) & mask;
--index;
firbuf[index] = result;
iirbuf[index] = result - accum;
*--firbuf = result;
*--iirbuf = result - accum;
m->sample_buffer[i + s->blockpos][channel] = result;
}
memcpy(fir->state, &firbuf[index], MAX_FIR_ORDER * sizeof(int32_t));
memcpy(iir->state, &iirbuf[index], MAX_IIR_ORDER * sizeof(int32_t));
memcpy(fir->state, firbuf, MAX_FIR_ORDER * sizeof(int32_t));
memcpy(iir->state, iirbuf, MAX_IIR_ORDER * sizeof(int32_t));
}
/** Read a block of PCM residual data (or actual if no filtering active). */