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PCM: remove partial sample buffer. Not needed

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This commit is contained in:
Gregory Nutt 2014-07-27 21:00:19 -06:00
parent c1b8e87918
commit 2efb594f50
1 changed files with 61 additions and 86 deletions
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147
audio/pcm_decode.c
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@ -125,8 +125,7 @@ struct pcm_decode_s
uint8_t subsample; /* Fast forward rate: See AUDIO_SUBSAMPLE_* defns */ uint8_t subsample; /* Fast forward rate: See AUDIO_SUBSAMPLE_* defns */
uint8_t skip; /* Number of samples to be skipped */ uint8_t skip; /* Number of samples to be skipped */
uint8_t npartial; /* Size of the partial sample */ uint8_t npartial; /* Size of the partially copied sample */
uint8_t partial[4]; /* Holds the partial sample */
/* REVISIT: I think we could get rid of all of this special buffer /* REVISIT: I think we could get rid of all of this special buffer
* processing. It seems like we should be able to do the sub-sampling * processing. It seems like we should be able to do the sub-sampling
@ -817,7 +816,7 @@ static FAR struct ap_buffer_s *pcm_subsample(FAR struct pcm_decode_s *priv,
skipsize = priv->align * (priv->subsample - 1); skipsize = priv->align * (priv->subsample - 1);
/* Let's deal with any partial sample data from the last buffer */ /* Let's deal with any partial samples from the last buffer */
if (priv->npartial > 0) if (priv->npartial > 0)
{ {
@ -832,37 +831,28 @@ static FAR struct ap_buffer_s *pcm_subsample(FAR struct pcm_decode_s *priv,
if (priv->npartial + srcsize < priv->align) if (priv->npartial + srcsize < priv->align)
{ {
dest = &priv->partial[priv->npartial]; /* Update the partial sample size */
src = &apb->samp[apb->curbyte];
memcpy(dest, src, srcsize);
priv->npartial += srcsize; priv->npartial += srcsize;
apb->curbyte += srcsize;
goto exit_apb_empty; /* And just return the buffer with no modification */
return apb;
} }
/* No, we do at least have enough to complete the partial sample */ /* No, we do at least have enough to complete the sample. Copy copy data
/* Copy the first part of the partial sample that was saved from * from the new audio buffer to complete the sample.
* the last buffer.
*/ */
src = priv->partial;
for (i = 0; i < priv->npartial; i++)
{
*dest++ = *src++;
}
priv->npartial = 0;
/* Now copy data from new audio buffer to complete the sample */
src = &apb->samp[apb->curbyte]; src = &apb->samp[apb->curbyte];
for (i = 0; i < priv->align; i++) for (i = priv->npartial; i < priv->align; i++)
{ {
*dest++ = *src++; *dest++ = *src++;
apb->curbyte++; apb->curbyte++;
} }
priv->npartial = 0;
/* Update the number of bytes in the working buffer and reset the skip /* Update the number of bytes in the working buffer and reset the skip
* value * value
*/ */
@ -904,55 +894,41 @@ static FAR struct ap_buffer_s *pcm_subsample(FAR struct pcm_decode_s *priv,
} }
} }
/* We have skipped over the required number of bytes and we are ready /* Copy the sample from the audio buffer into the working buffer. */
* to take the next sample. Is there space for a whole sample in the
* buffer?
*/
else if (srcsize < priv->align)
{
/* No.. copy the partial sample to the partial sample buffer */
dest = priv->partial;
for (i = 0; i < srcsize; i++)
{
*dest++ = *src++;
}
priv->npartial = srcsize;
apb->curbyte += srcsize;
/* We are finished with this audio buffer. On the next buffer,
* the fact that skip == 0 and that priv->npartial > 0 will kick
* off the re-synchronization logic at the beginning of this
* function.
*/
goto exit_apb_empty;
}
/* Plenty of space! Copy the sample from the audio buffer into the
* working buffer.
*/
else else
{ {
unsigned int copysize;
/* Do we have space for the whole sample? */
if (srcsize < priv->align)
{
/* No.. this is a partial copy */
copysize = srcsize;
priv->npartial = srcsize;
}
else
{
copysize = priv->align;
priv->skip = skipsize;
}
/* Now copy the sample from new audio buffer to working buffer */ /* Now copy the sample from new audio buffer to working buffer */
for (i = 0; i < priv->align; i++) for (i = 0; i < copysize; i++)
{ {
*dest++ = *src++; *dest++ = *src++;
} }
/* Update indices and sizes and reset the skip value */ /* Update indices and sizes and reset the skip value */
apb->curbyte += priv->align; apb->curbyte += copysize;
srcsize -= priv->align; srcsize -= copysize;
work->nbytes += priv->align; work->nbytes += copysize;
destsize -= priv->align; destsize -= copysize;
priv->skip = skipsize;
} }
} }
@ -1001,43 +977,42 @@ static FAR struct ap_buffer_s *pcm_subsample(FAR struct pcm_decode_s *priv,
} }
} }
/* We have skipped over the required number of bytes and we are /* Copy the sample from the end of the audio buffer to the beginning. */
* ready to take the next sample. Is there space for a whole
* sample in the buffer?
*/
else if (srcsize < priv->align)
{
/* No.. copy the partial sample to the partial sample buffer */
dest = priv->partial;
for (i = 0; i < srcsize; i++)
{
*dest++ = *src++;
}
priv->npartial = srcsize;
break;
}
/* Plenty of space! Copy the sample from the end of the audio
* buffer to the beginning.
*/
else else
{ {
unsigned int copysize;
/* Do we have space for the whole sample? */
if (srcsize < priv->align)
{
/* No.. this is a partial copy */
copysize = srcsize;
priv->npartial = srcsize;
}
else
{
/* Copy the whole sample and re-arm the skip size */
copysize = priv->align;
priv->skip = skipsize;
}
/* Now copy the sample from new audio buffer to working buffer */ /* Now copy the sample from new audio buffer to working buffer */
for (i = 0; i < priv->align; i++) for (i = 0; i < copysize; i++)
{ {
*dest++ = *src++; *dest++ = *src++;
} }
/* Update indices and sizes and reset the skip value */ /* Updates bytes available in the source buffer and bytes
* remaining in the dest buffer.
*/
srcsize -= priv->align; srcsize -= copysize;
destsize -= priv->align; destsize -= copysize;
priv->skip = skipsize;
} }
} }