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authorRicardo Biehl Pasquali <pasqualirb@gmail.com>2018-12-18 23:26:15 -0200
committerRicardo Biehl Pasquali <pasqualirb@gmail.com>2019-01-08 16:48:19 -0200
commit4ee09a97af1f770241e24e4d395e28c1ad1343c5 (patch)
treef304dd079230c98591789dee91e7f711371a2321 /src
parent7aacaed904d237b2ae737a8bc8104101585446cb (diff)
pcm: Rewrite pcm_mmap_transfer() for compatibility
Make pcm_mmap_transfer() compatible with read/write IO. start_threshold check was not valid for capture. pcm->running checks were removed. NOIRQ fallback was removed. Clocks of sound devices may differ from the system, leading to desynchronization. Signed-off-by: Ricardo Biehl Pasquali <pasqualirb@gmail.com>
Diffstat (limited to 'src')
-rw-r--r--src/pcm.c125
1 files changed, 67 insertions, 58 deletions
diff --git a/src/pcm.c b/src/pcm.c
index 474295a..5ba01ca 100644
--- a/src/pcm.c
+++ b/src/pcm.c
@@ -1386,81 +1386,89 @@ int pcm_wait(struct pcm *pcm, int timeout)
return 1;
}
-int pcm_mmap_transfer(struct pcm *pcm, const void *buffer, unsigned int bytes)
+/*
+ * Transfer data to/from mmaped buffer. This imitates the
+ * behavior of read/write system calls.
+ *
+ * However, this doesn't seems to offer any advantage over
+ * the read/write syscalls. Should it be removed?
+ */
+int pcm_mmap_transfer(struct pcm *pcm, void *buffer, unsigned int frames)
{
- int err = 0, frames, avail;
- unsigned int offset = 0, count;
+ int is_playback;
- if (bytes == 0)
- return 0;
+ int state;
+ unsigned int avail;
+ unsigned int user_offset;
- count = pcm_bytes_to_frames(pcm, bytes);
+ int err;
+ int tmp;
- while (count > 0) {
+ is_playback = !(pcm->flags & PCM_IN);
- /* get the available space for writing new frames */
- avail = pcm_avail_update(pcm);
- if (avail < 0) {
- fprintf(stderr, "cannot determine available mmap frames");
- return err;
- }
+ if (frames == 0)
+ return 0;
- /* start the audio if we reach the threshold */
- if (!pcm->running &&
- (pcm->buffer_size - avail) >= pcm->config.start_threshold) {
- if (pcm_start(pcm) < 0) {
- fprintf(stderr, "start error: hw 0x%x app 0x%x avail 0x%x\n",
- (unsigned int)pcm->mmap_status->hw_ptr,
- (unsigned int)pcm->mmap_control->appl_ptr,
- avail);
- return -errno;
- }
+ /* update hardware pointer and get state */
+ err = pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_HWSYNC |
+ SNDRV_PCM_SYNC_PTR_APPL |
+ SNDRV_PCM_SYNC_PTR_AVAIL_MIN);
+ if (err == -1)
+ return -1;
+ state = pcm->mmap_status->state;
+
+ /* start capture if frames >= threshold */
+ if (!is_playback && state == PCM_STATE_PREPARED) {
+ if (frames >= pcm->config.start_threshold) {
+ err = ioctl(pcm->fd, SNDRV_PCM_IOCTL_START);
+ if (err == -1)
+ return -1;
+ /* state = PCM_STATE_RUNNING */
+ } else {
+ /* nothing to do */
+ return 0;
}
+ }
- /* sleep until we have space to write new frames */
- if (pcm->running &&
- (unsigned int)avail < pcm->mmap_control->avail_min) {
- int time = -1;
+ avail = pcm_mmap_avail(pcm);
+ user_offset = 0;
- if (pcm->flags & PCM_NOIRQ)
- time = (pcm->buffer_size - avail - pcm->mmap_control->avail_min)
- / pcm->noirq_frames_per_msec;
+ while (frames) {
+ if (!avail) {
+ if (pcm->flags & PCM_NONBLOCK) {
+ errno = EAGAIN;
+ break;
+ }
- err = pcm_wait(pcm, time);
+ /* wait for interrupt */
+ err = pcm_wait(pcm, -1);
if (err < 0) {
- pcm->running = 0;
- fprintf(stderr, "wait error: hw 0x%x app 0x%x avail 0x%x\n",
- (unsigned int)pcm->mmap_status->hw_ptr,
- (unsigned int)pcm->mmap_control->appl_ptr,
- avail);
- pcm->mmap_control->appl_ptr = 0;
- return err;
+ errno = -err;
+ break;
}
- continue;
- }
- frames = count;
- if (frames > avail)
- frames = avail;
+ /* get hardware pointer */
+ avail = pcm_avail_update(pcm);
+ }
- if (!frames)
+ tmp = pcm_mmap_transfer_areas(pcm, buffer, user_offset, frames);
+ if (tmp < 0)
break;
- /* copy frames from buffer */
- frames = pcm_mmap_transfer_areas(pcm, (void *)buffer, offset, frames);
- if (frames < 0) {
- fprintf(stderr, "write error: hw 0x%x app 0x%x avail 0x%x\n",
- (unsigned int)pcm->mmap_status->hw_ptr,
- (unsigned int)pcm->mmap_control->appl_ptr,
- avail);
- return frames;
- }
+ user_offset += tmp;
+ frames -= tmp;
+ avail -= tmp;
- offset += frames;
- count -= frames;
+ /* start playback if written >= start_threshold */
+ if (is_playback && state == PCM_STATE_PREPARED &&
+ pcm->buffer_size - avail >= pcm->config.start_threshold) {
+ err = ioctl(pcm->fd, SNDRV_PCM_IOCTL_START);
+ if (err == -1)
+ break;
+ }
}
- return 0;
+ return user_offset ? (int) user_offset : -1;
}
int pcm_mmap_write(struct pcm *pcm, const void *data, unsigned int count)
@@ -1468,7 +1476,8 @@ int pcm_mmap_write(struct pcm *pcm, const void *data, unsigned int count)
if ((~pcm->flags) & (PCM_OUT | PCM_MMAP))
return -ENOSYS;
- return pcm_mmap_transfer(pcm, (void *)data, count);
+ return pcm_mmap_transfer(pcm, (void *)data,
+ pcm_bytes_to_frames(pcm, count));
}
int pcm_mmap_read(struct pcm *pcm, void *data, unsigned int count)
@@ -1476,7 +1485,7 @@ int pcm_mmap_read(struct pcm *pcm, void *data, unsigned int count)
if ((~pcm->flags) & (PCM_IN | PCM_MMAP))
return -ENOSYS;
- return pcm_mmap_transfer(pcm, data, count);
+ return pcm_mmap_transfer(pcm, data, pcm_bytes_to_frames(pcm, count));
}
/** Gets the delay of the PCM, in terms of frames.