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pcm: add mmap_begin callback to snd_pcm_fast_ops_t api

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main motivation for adding the callback is to use it to enable operation
on mmaped buffer before user access for pcm_file plugin

support for MMAP read access with masking by data from input file is not
implemented for pcm_file plugin, by adding this callback implementing
such feature can be done by rewriting next continuous portion of buffer
on each mmap_begin call

plugins like softvol use pcm_plugin interface and overwrite the buffer by
looping around it in avail_update callback, this patch hopes to simplify
the task by adding new api callback, removing the need for rewriting
pcm_file (to use pcm_plugin callbacks) and careful checking when looping
around whole mmaped buffer

Signed-off-by: Adam Miartus <amiartus@de.adit-jv.com>
Reviewed-by: Timo Wischer <twischer@de.adit-jv.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Adam Miartus 2019-05-23 15:00:39 +02:00 • committed by Takashi Iwai
parent 108a2f4379
commit e520f45480
2 changed files with 7 additions and 0 deletions
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6
src/pcm/pcm.c
View file

@ -7129,7 +7129,13 @@ int __snd_pcm_mmap_begin(snd_pcm_t *pcm, const snd_pcm_channel_area_t **areas,
snd_pcm_uframes_t f; snd_pcm_uframes_t f;
snd_pcm_uframes_t avail; snd_pcm_uframes_t avail;
const snd_pcm_channel_area_t *xareas; const snd_pcm_channel_area_t *xareas;
assert(pcm && areas && offset && frames); assert(pcm && areas && offset && frames);
if (pcm->fast_ops->mmap_begin)
return pcm->fast_ops->mmap_begin(pcm->fast_op_arg, areas, offset, frames);
/* fallback for plugins that do not specify new callback */
xareas = snd_pcm_mmap_areas(pcm); xareas = snd_pcm_mmap_areas(pcm);
if (xareas == NULL) if (xareas == NULL)
return -EBADFD; return -EBADFD;

1
src/pcm/pcm_local.h
View file

@ -184,6 +184,7 @@ typedef struct {
int (*poll_descriptors)(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int space); /* locked */ int (*poll_descriptors)(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int space); /* locked */
int (*poll_revents)(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int nfds, unsigned short *revents); /* locked */ int (*poll_revents)(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int nfds, unsigned short *revents); /* locked */
int (*may_wait_for_avail_min)(snd_pcm_t *pcm, snd_pcm_uframes_t avail); int (*may_wait_for_avail_min)(snd_pcm_t *pcm, snd_pcm_uframes_t avail);
int (*mmap_begin)(snd_pcm_t *pcm, const snd_pcm_channel_area_t **areas, snd_pcm_uframes_t *offset, snd_pcm_uframes_t *frames); /* locked */
} snd_pcm_fast_ops_t; } snd_pcm_fast_ops_t;
struct _snd_pcm { struct _snd_pcm {