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 --- src/pcm/pcm.c | 6 ++++++ src/pcm/pcm_local.h | 1 + 2 files changed, 7 insertions(+)
diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c index 3a71d79..323926e 100644 --- a/src/pcm/pcm.c +++ b/src/pcm/pcm.c @@ -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 avail; const snd_pcm_channel_area_t *xareas; + 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); if (xareas == NULL) return -EBADFD; diff --git a/src/pcm/pcm_local.h b/src/pcm/pcm_local.h index d52229d..d5726eb 100644 --- a/src/pcm/pcm_local.h +++ b/src/pcm/pcm_local.h @@ -184,6 +184,7 @@ typedef struct { 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 (*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;
struct _snd_pcm {