diff options
| -rw-r--r-- | include/tinyalsa/asoundlib.h | 10 | ||||
| -rw-r--r-- | pcm.c | 110 |
2 files changed, 119 insertions, 1 deletions
diff --git a/include/tinyalsa/asoundlib.h b/include/tinyalsa/asoundlib.h index 14511c9..7b13c0d 100644 --- a/include/tinyalsa/asoundlib.h +++ b/include/tinyalsa/asoundlib.h @@ -29,6 +29,7 @@ #ifndef ASOUNDLIB_H #define ASOUNDLIB_H +#include <sys/time.h> /* * PCM API @@ -90,6 +91,15 @@ unsigned int pcm_get_buffer_size(struct pcm *pcm); /* Returns the pcm latency in ms */ unsigned int pcm_get_latency(struct pcm *pcm); +/* Returns available frames in pcm buffer and corresponding time stamp. + * For an input stream, frames available are frames ready for the + * application to read. + * For an output stream, frames available are the number of empty frames available + * for the application to write. + */ +int pcm_get_htimestamp(struct pcm *pcm, unsigned int *avail, + struct timespec *tstamp); + /* Write data to the fifo. * Will start playback on the first write or on a write that * occurs after a fifo underrun. @@ -137,6 +137,9 @@ struct pcm { unsigned int buffer_size; char error[PCM_ERROR_MAX]; struct pcm_config config; + struct snd_pcm_mmap_status *mmap_status; + struct snd_pcm_mmap_control *mmap_control; + struct snd_pcm_sync_ptr *sync_ptr; }; unsigned int pcm_get_buffer_size(struct pcm *pcm) @@ -187,6 +190,101 @@ static unsigned int pcm_format_to_bits(enum pcm_format format) }; } +static int pcm_sync_ptr(struct pcm *pcm, int flags) { + if (pcm->sync_ptr) { + pcm->sync_ptr->flags = flags; + if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_SYNC_PTR, pcm->sync_ptr) < 0) + return -1; + } + return 0; +} + +static int pcm_hw_mmap_status(struct pcm *pcm) { + + if (pcm->sync_ptr) + return 0; + + int page_size = sysconf(_SC_PAGE_SIZE); + pcm->mmap_status = mmap(NULL, page_size, PROT_READ, MAP_FILE | MAP_SHARED, + pcm->fd, SNDRV_PCM_MMAP_OFFSET_STATUS); + if (pcm->mmap_status == MAP_FAILED) + pcm->mmap_status = NULL; + if (!pcm->mmap_status) + goto mmap_error; + + pcm->mmap_control = mmap(NULL, page_size, PROT_READ | PROT_WRITE, + MAP_FILE | MAP_SHARED, pcm->fd, SNDRV_PCM_MMAP_OFFSET_CONTROL); + if (pcm->mmap_control == MAP_FAILED) + pcm->mmap_control = NULL; + if (!pcm->mmap_control) { + munmap(pcm->mmap_status, page_size); + pcm->mmap_status = NULL; + goto mmap_error; + } + pcm->mmap_control->avail_min = 1; + + return 0; + +mmap_error: + + pcm->sync_ptr = calloc(1, sizeof(*pcm->sync_ptr)); + if (!pcm->sync_ptr) + return -ENOMEM; + pcm->mmap_status = &pcm->sync_ptr->s.status; + pcm->mmap_control = &pcm->sync_ptr->c.control; + pcm->mmap_control->avail_min = 1; + pcm_sync_ptr(pcm, 0); + + return 0; +} + +static void pcm_hw_munmap_status(struct pcm *pcm) { + if (pcm->sync_ptr) { + free(pcm->sync_ptr); + pcm->sync_ptr = NULL; + } else { + int page_size = sysconf(_SC_PAGE_SIZE); + if (pcm->mmap_status) + munmap(pcm->mmap_status, page_size); + if (pcm->mmap_control) + munmap(pcm->mmap_control, page_size); + } + pcm->mmap_status = NULL; + pcm->mmap_control = NULL; +} + +int pcm_get_htimestamp(struct pcm *pcm, unsigned int *avail, + struct timespec *tstamp) +{ + int frames; + int rc; + snd_pcm_uframes_t hw_ptr; + + if (!pcm_is_ready(pcm)) + return -1; + + rc = pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_APPL|SNDRV_PCM_SYNC_PTR_HWSYNC); + if (rc < 0) + return -1; + + *tstamp = pcm->mmap_status->tstamp; + if (tstamp->tv_sec == 0 && tstamp->tv_nsec == 0) + return -1; + + hw_ptr = pcm->mmap_status->hw_ptr; + if (pcm->flags & PCM_IN) + frames = hw_ptr - pcm->mmap_control->appl_ptr; + else + frames = hw_ptr + pcm->buffer_size - pcm->mmap_control->appl_ptr; + + if (frames < 0) + return -1; + + *avail = (unsigned int)frames; + + return 0; +} + int pcm_write(struct pcm *pcm, void *data, unsigned int count) { struct snd_xferi x; @@ -261,11 +359,14 @@ int pcm_close(struct pcm *pcm) if (pcm == &bad_pcm) return 0; + pcm_hw_munmap_status(pcm); + if (pcm->fd >= 0) close(pcm->fd); pcm->running = 0; pcm->buffer_size = 0; pcm->fd = -1; + free(pcm); return 0; } @@ -277,6 +378,7 @@ struct pcm *pcm_open(unsigned int card, unsigned int device, struct snd_pcm_hw_params params; struct snd_pcm_sw_params sparams; char fn[256]; + int rc; pcm = calloc(1, sizeof(struct pcm)); if (!pcm || !config) @@ -322,7 +424,7 @@ struct pcm *pcm_open(unsigned int card, unsigned int device, } memset(&sparams, 0, sizeof(sparams)); - sparams.tstamp_mode = SNDRV_PCM_TSTAMP_NONE; + sparams.tstamp_mode = SNDRV_PCM_TSTAMP_ENABLE; sparams.period_step = 1; sparams.avail_min = 1; sparams.start_threshold = config->period_count * config->period_size; @@ -336,6 +438,12 @@ struct pcm *pcm_open(unsigned int card, unsigned int device, goto fail; } + rc = pcm_hw_mmap_status(pcm); + if (rc < 0) { + oops(pcm, rc, "mmap status failed"); + goto fail; + } + pcm->buffer_size = config->period_count * config->period_size; pcm->underruns = 0; return pcm; |