[alsa-devel] [PATCH 0/2] add pcm_file support in MMAP read access mode
adds support for overwritting input buffer in MMAP access mode for in pcm_file plugin
new api pcm_fast_ops callback mmap_begin is introduced to ease the operation needed to overwrite mmaped buffer. this allows to modify only the next continuous part of data in ring buffer.
Adam Miartus (2): pcm: add mmap_begin callback to snd_pcm_fast_ops_t api pcm_file: add infile read support for mmap mode
src/pcm/pcm.c | 6 ++++++ src/pcm/pcm_file.c | 31 +++++++++++++++++++++++++++++++ src/pcm/pcm_local.h | 1 + 3 files changed, 38 insertions(+)
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 {
mmap_begin callback is used to copy data from input file to mmaped buffer
guard for corner use of api (multiple mmap_begin calls by user) is introduced to check if next continuous buffer was already overwritten
buffer is overwritten with input file data only in case of stream capture
Signed-off-by: Adam Miartus amiartus@de.adit-jv.com Reviewed-by: Timo Wischer twischer@de.adit-jv.com --- src/pcm/pcm_file.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)
diff --git a/src/pcm/pcm_file.c b/src/pcm/pcm_file.c index 8e2c70b..52cc10a 100644 --- a/src/pcm/pcm_file.c +++ b/src/pcm/pcm_file.c @@ -88,6 +88,7 @@ typedef struct { size_t buffer_bytes; struct wav_fmt wav_header; size_t filelen; + char ifmmap_overwritten; } snd_pcm_file_t;
#if __BYTE_ORDER == __LITTLE_ENDIAN @@ -630,6 +631,8 @@ static snd_pcm_sframes_t snd_pcm_file_mmap_commit(snd_pcm_t *pcm, const snd_pcm_channel_area_t *areas; snd_pcm_sframes_t result;
+ file->ifmmap_overwritten = 0; + result = snd_pcm_mmap_begin(file->gen.slave, &areas, &ofs, &siz); if (result >= 0) { assert(ofs == offset && siz == size); @@ -640,6 +643,32 @@ static snd_pcm_sframes_t snd_pcm_file_mmap_commit(snd_pcm_t *pcm, return result; }
+static int snd_pcm_file_mmap_begin(snd_pcm_t *pcm, const snd_pcm_channel_area_t **areas, + snd_pcm_uframes_t *offset, snd_pcm_uframes_t *frames) +{ + snd_pcm_file_t *file = pcm->private_data; + snd_pcm_channel_area_t areas_if[pcm->channels]; + snd_pcm_uframes_t frames_if; + void *buffer = NULL; + int result; + + result = snd_pcm_mmap_begin(file->gen.slave, areas, offset, frames); + if (result < 0) + return result; + + if (pcm->stream != SND_PCM_STREAM_CAPTURE) + return result; + + /* user may run mmap_begin without mmap_commit multiple times in row */ + if (file->ifmmap_overwritten) + return result; + file->ifmmap_overwritten = 1; + + snd_pcm_file_areas_read_infile(pcm, *areas, *offset, *frames); + + return result; +} + static int snd_pcm_file_hw_free(snd_pcm_t *pcm) { snd_pcm_file_t *file = pcm->private_data; @@ -666,6 +695,7 @@ static int snd_pcm_file_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params) file->wbuf_size = slave->buffer_size * 2; file->wbuf_size_bytes = snd_pcm_frames_to_bytes(slave, file->wbuf_size); file->wbuf_used_bytes = 0; + file->ifmmap_overwritten = 0; assert(!file->wbuf); file->wbuf = malloc(file->wbuf_size_bytes); if (file->wbuf == NULL) { @@ -777,6 +807,7 @@ static const snd_pcm_fast_ops_t snd_pcm_file_fast_ops = { .poll_descriptors = snd_pcm_generic_poll_descriptors, .poll_revents = snd_pcm_generic_poll_revents, .htimestamp = snd_pcm_generic_htimestamp, + .mmap_begin = snd_pcm_file_mmap_begin, };
/**
On Thu, 23 May 2019 15:00:38 +0200, Adam Miartus wrote:
adds support for overwritting input buffer in MMAP access mode for in pcm_file plugin
new api pcm_fast_ops callback mmap_begin is introduced to ease the operation needed to overwrite mmaped buffer. this allows to modify only the next continuous part of data in ring buffer.
Adam Miartus (2): pcm: add mmap_begin callback to snd_pcm_fast_ops_t api pcm_file: add infile read support for mmap mode
OK, now applied both patches. Thanks!
Takashi
participants (2)
-
Adam Miartus -
Takashi Iwai