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Added snd_pcm_mmap_commit_partial().

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This commit is contained in:
Jaroslav Kysela 2001-12-10 10:52:04 +00:00
parent b7b11c3558
commit bbcf77116d
2 changed files with 51 additions and 20 deletions
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7
include/pcm.h
View file

@ -795,8 +795,13 @@ int snd_pcm_mmap_begin_avail(snd_pcm_t *pcm,
snd_pcm_uframes_t *offset,
snd_pcm_uframes_t *frames,
snd_pcm_uframes_t avail);
int snd_pcm_mmap_commit(snd_pcm_t *pcm, snd_pcm_uframes_t offset,
int snd_pcm_mmap_commit(snd_pcm_t *pcm,
snd_pcm_uframes_t offset,
snd_pcm_uframes_t frames);
int snd_pcm_mmap_commit_partial(snd_pcm_t *pcm,
snd_pcm_uframes_t offset,
snd_pcm_uframes_t frames,
snd_pcm_uframes_t *commited);
snd_pcm_sframes_t snd_pcm_mmap_writei(snd_pcm_t *pcm, const void *buffer, snd_pcm_uframes_t size);
snd_pcm_sframes_t snd_pcm_mmap_readi(snd_pcm_t *pcm, void *buffer, snd_pcm_uframes_t size);
snd_pcm_sframes_t snd_pcm_mmap_writen(snd_pcm_t *pcm, void **bufs, snd_pcm_uframes_t size);

64
src/pcm/pcm.c
View file

@ -259,10 +259,9 @@ containing the direct pointers to memory and sample position description
in \link ::snd_pcm_channel_area_t \endlink structure. After application
transfers the data in the memory areas, then it must be acknowledged
the end of transfer via \link ::snd_pcm_mmap_commit() \endlink function
to allow the ALSA library update the pointers to ring buffer. This sort of
to allow the ALSA library update the pointers to ring buffer. This kind of
communication is also called "zero-copy", because the device does not require
to copy the samples from application to another place in system memory.
\par
If you like to use the compatibility functions in mmap mode, there are
@ -4844,27 +4843,12 @@ int snd_pcm_mmap_begin(snd_pcm_t *pcm,
snd_pcm_uframes_t *offset,
snd_pcm_uframes_t *frames)
{
snd_pcm_uframes_t cont;
snd_pcm_sframes_t avail;
snd_pcm_uframes_t f;
assert(pcm && areas && offset && frames);
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;
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;
return snd_pcm_mmap_begin_avail(pcm, areas, offset, frames, avail);
}
/**
@ -4875,6 +4859,12 @@ int snd_pcm_mmap_begin(snd_pcm_t *pcm,
* \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
*
* See snd_pcm_mmap_begin() function for more details. The only difference
* is in the optimization for applications using snd_pcm_avail_update()
* directly before snd_pcm_mmap_begin() call. In the case, this function
* should be used to avoid twice or more calls to time consuming
* snd_pcm_avail_update() function.
*/
int snd_pcm_mmap_begin_avail(snd_pcm_t *pcm,
const snd_pcm_channel_area_t **areas,
@ -4965,6 +4955,42 @@ int snd_pcm_mmap_commit(snd_pcm_t *pcm, snd_pcm_uframes_t offset,
return pcm->fast_ops->mmap_commit(pcm->fast_op_arg, offset, frames);
}
/**
* \brief Application has completed the access to area requested with #snd_pcm_mmap_begin
* \param pcm PCM handle
* \param offset area offset in area steps (== frames)
* \param size area portion size in frames
* \param commited count of successfully commited frames
* \return 0 on success otherwise a negative error code
*
* See snd_pcm_mmap_commit() function. The only difference is the
* #commited parameter returning count of successfully commited frames
* when an error occured. This parameter is equal to frames when
* no error occured. This function is a helper for more precise xrun
* recovery algorithms.
*/
int snd_pcm_mmap_commit_partial(snd_pcm_t *pcm,
snd_pcm_uframes_t offset,
snd_pcm_uframes_t frames,
snd_pcm_uframes_t *commited)
{
int err;
snd_pcm_uframes_t appl_ptr;
assert(pcm && commited);
assert(offset == *pcm->appl_ptr % pcm->buffer_size);
assert(frames <= snd_pcm_mmap_avail(pcm));
appl_ptr = *pcm->appl_ptr;
err = pcm->fast_ops->mmap_commit(pcm->fast_op_arg, offset, frames);
if (err < 0) {
*commited = *pcm->appl_ptr - appl_ptr;
assert(*commited <= pcm->buffer_size);
return err;
}
*commited = frames;
return err;
}
#ifndef DOC_HIDDEN
int _snd_pcm_poll_descriptor(snd_pcm_t *pcm)