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pcm: ioplug: Provide hw_avail helper function for plugins

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This function can be called without calling snd_pcm_avail_update().

The call to snd_pcm_avail_update() can take some time.
Therefore some developers would not like to call it from a real-time
context (e.g. from JACK client context).

Signed-off-by: Timo Wischer <twischer@de.adit-jv.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Timo Wischer 2018-03-13 09:34:42 +01:00 • committed by Takashi Iwai
parent 9c2fb31d0e
commit df2452cc6a
3 changed files with 59 additions and 7 deletions
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5
include/pcm_ioplug.h
View file

@ -234,6 +234,11 @@ int snd_pcm_ioplug_set_param_list(snd_pcm_ioplug_t *io, int type, unsigned int n
/* change PCM status */
int snd_pcm_ioplug_set_state(snd_pcm_ioplug_t *ioplug, snd_pcm_state_t state);
/* calucalte the available frames */
snd_pcm_uframes_t snd_pcm_ioplug_hw_avail(const snd_pcm_ioplug_t * const ioplug,
const snd_pcm_uframes_t hw_ptr,
const snd_pcm_uframes_t appl_ptr);
/** \} */
#endif /* __ALSA_PCM_IOPLUG_H */

26
src/pcm/pcm_ioplug.c
View file

@ -1148,3 +1148,29 @@ int snd_pcm_ioplug_set_state(snd_pcm_ioplug_t *ioplug, snd_pcm_state_t state)
ioplug->state = state;
return 0;
}
/**
* \brief Get the available frames. This function can be used to calculate the
* the available frames before calling #snd_pcm_avail_update()
* \param ioplug the ioplug handle
* \param hw_ptr hardware pointer in frames
* \param appl_ptr application pointer in frames
* \return available frames for the hardware
*/
snd_pcm_uframes_t snd_pcm_ioplug_hw_avail(const snd_pcm_ioplug_t * const ioplug,
const snd_pcm_uframes_t hw_ptr,
const snd_pcm_uframes_t appl_ptr)
{
/* available data/space which can be transferred by the user
* application
*/
const snd_pcm_uframes_t user_avail = __snd_pcm_avail(ioplug->pcm,
hw_ptr, appl_ptr);
if (user_avail > ioplug->pcm->buffer_size) {
/* there was an Xrun */
return 0;
}
/* available data/space which can be transferred by the DMA */
return ioplug->pcm->buffer_size - user_avail;
}

35
src/pcm/pcm_local.h
View file

@ -467,10 +467,12 @@ static inline int snd_pcm_check_error(snd_pcm_t *pcm, int err)
return err;
}
static inline snd_pcm_uframes_t snd_pcm_mmap_playback_avail(snd_pcm_t *pcm)
static inline snd_pcm_uframes_t __snd_pcm_playback_avail(snd_pcm_t *pcm,
const snd_pcm_uframes_t hw_ptr,
const snd_pcm_uframes_t appl_ptr)
{
snd_pcm_sframes_t avail;
avail = *pcm->hw.ptr + pcm->buffer_size - *pcm->appl.ptr;
avail = hw_ptr + pcm->buffer_size - appl_ptr;
if (avail < 0)
avail += pcm->boundary;
else if ((snd_pcm_uframes_t) avail >= pcm->boundary)
@ -478,21 +480,40 @@ static inline snd_pcm_uframes_t snd_pcm_mmap_playback_avail(snd_pcm_t *pcm)
return avail;
}
static inline snd_pcm_uframes_t snd_pcm_mmap_capture_avail(snd_pcm_t *pcm)
static inline snd_pcm_uframes_t snd_pcm_mmap_playback_avail(snd_pcm_t *pcm)
{
return __snd_pcm_playback_avail(pcm, *pcm->hw.ptr, *pcm->appl.ptr);
}
static inline snd_pcm_uframes_t __snd_pcm_capture_avail(snd_pcm_t *pcm,
const snd_pcm_uframes_t hw_ptr,
const snd_pcm_uframes_t appl_ptr)
{
snd_pcm_sframes_t avail;
avail = *pcm->hw.ptr - *pcm->appl.ptr;
avail = hw_ptr - appl_ptr;
if (avail < 0)
avail += pcm->boundary;
return avail;
}
static inline snd_pcm_uframes_t snd_pcm_mmap_avail(snd_pcm_t *pcm)
static inline snd_pcm_uframes_t snd_pcm_mmap_capture_avail(snd_pcm_t *pcm)
{
return __snd_pcm_capture_avail(pcm, *pcm->hw.ptr, *pcm->appl.ptr);
}
static inline snd_pcm_uframes_t __snd_pcm_avail(snd_pcm_t *pcm,
const snd_pcm_uframes_t hw_ptr,
const snd_pcm_uframes_t appl_ptr)
{
if (pcm->stream == SND_PCM_STREAM_PLAYBACK)
return snd_pcm_mmap_playback_avail(pcm);
return __snd_pcm_playback_avail(pcm, hw_ptr, appl_ptr);
else
return snd_pcm_mmap_capture_avail(pcm);
return __snd_pcm_capture_avail(pcm, hw_ptr, appl_ptr);
}
static inline snd_pcm_uframes_t snd_pcm_mmap_avail(snd_pcm_t *pcm)
{
return __snd_pcm_avail(pcm, *pcm->hw.ptr, *pcm->appl.ptr);
}
static inline snd_pcm_sframes_t snd_pcm_mmap_playback_hw_avail(snd_pcm_t *pcm)