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- added snd_pcm_mmap_begin_avail function; it is optimized for use after

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snd_pcm_avail_update() call
- fixed broken hw_ptr management inside snd_pcm_plugin code
This commit is contained in:
Jaroslav Kysela 2001-12-09 18:41:23 +00:00
parent b63e44aab0
commit b7b11c3558
4 changed files with 187 additions and 69 deletions
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63
src/pcm/pcm.c
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@ -4845,7 +4845,7 @@ int snd_pcm_mmap_begin(snd_pcm_t *pcm,
snd_pcm_uframes_t *frames)
{
snd_pcm_uframes_t cont;
snd_pcm_uframes_t avail;
snd_pcm_sframes_t avail;
snd_pcm_uframes_t f;
assert(pcm && areas && offset && frames);
if (pcm->stopped_areas &&
@ -4855,7 +4855,43 @@ int snd_pcm_mmap_begin(snd_pcm_t *pcm,
*areas = pcm->running_areas;
*offset = *pcm->appl_ptr % pcm->buffer_size;
cont = pcm->buffer_size - *offset;
avail = snd_pcm_mmap_avail(pcm);
avail = snd_pcm_avail_update(pcm);
if (avail < 0)
return avail;
f = *frames;
if (f > (snd_pcm_uframes_t)avail)
f = avail;
if (f > cont)
f = cont;
*frames = f;
return 0;
}
/**
* \brief Application request to access a portion of direct (mmap) area
* \param pcm PCM handle
* \param areas Returned mmap channel areas
* \param offset Returned mmap area offset in area steps (== frames)
* \param size mmap area portion size in frames (wanted on entry, contiguous available on exit)
* \param avail available frames (result from snd_pcm_avail_update())
* \return 0 on success otherwise a negative error code
*/
int snd_pcm_mmap_begin_avail(snd_pcm_t *pcm,
const snd_pcm_channel_area_t **areas,
snd_pcm_uframes_t *offset,
snd_pcm_uframes_t *frames,
snd_pcm_uframes_t avail)
{
snd_pcm_uframes_t cont;
snd_pcm_uframes_t f;
assert(pcm && areas && offset && frames && avail <= pcm->buffer_size);
if (pcm->stopped_areas &&
snd_pcm_state(pcm) != SND_PCM_STATE_RUNNING)
*areas = pcm->stopped_areas;
else
*areas = pcm->running_areas;
*offset = *pcm->appl_ptr % pcm->buffer_size;
cont = pcm->buffer_size - *offset;
f = *frames;
if (f > avail)
f = avail;
@ -4879,7 +4915,7 @@ int snd_pcm_mmap_begin(snd_pcm_t *pcm,
* count that snd_pcm_mmap_begin() returned. Each call to snd_pcm_mmap_begin()
* must be followed by a call to snd_pcm_mmap_commit().
*
* Example:
* Example #1:
\code
double phase = 0;
const snd_pcm_area_t *areas;
@ -4894,6 +4930,27 @@ int snd_pcm_mmap_begin(snd_pcm_t *pcm,
err = snd_pcm_mmap_commit(pcm_handle, offset, frames);
if (err < 0)
error(err);
\endcode
*
* Example #2 (determine available frame count at beginning):
\code
double phase = 0;
const snd_pcm_area_t *areas;
snd_pcm_sframes_t avail;
snd_pcm_uframes_t offset, frames;
avail = snd_pcm_avail_update(pcm);
if (avail < 0)
error(avail);
frames = frame_buffer_size > avail ? avail : frame_buffer_size;
err = snd_pcm_mmap_begin_avail(pcm_handle, &areas, &offset, &frames, avail);
if (err < 0)
error(err);
// this function fills the areas from offset with count of frames
generate_sine(areas, offset, frames, &phase);
err = snd_pcm_mmap_commit(pcm_handle, offset, frames);
if (err < 0)
error(err);
\endcode
*
* Look to the \ref example_test_pcm "Sine-wave generator" example