diff options
| -rw-r--r-- | include/tinyalsa/pcm.h | 9 | ||||
| -rw-r--r-- | src/pcm.c | 15 |
2 files changed, 21 insertions, 3 deletions
diff --git a/include/tinyalsa/pcm.h b/include/tinyalsa/pcm.h index 5e976d4..c68a77d 100644 --- a/include/tinyalsa/pcm.h +++ b/include/tinyalsa/pcm.h @@ -88,6 +88,15 @@ extern "C" { */ #define PCM_MONOTONIC 0x00000008 +/** If used with @pcm_open and @pcm_params_get, + * it will not cause the function to block if + * the PCM is not available. It will also cause + * the functions @ref pcm_readi and @ref pcm_writei + * to exit if they would cause the caller to wait. + * @ingroup libtinyalsa-pcm + * */ +#define PCM_NONBLOCK 0x00000010 + /** For inputs, this means the PCM is recording audio samples. * For outputs, this means the PCM is playing audio samples. * @ingroup libtinyalsa-pcm @@ -818,9 +818,13 @@ struct pcm_params *pcm_params_get(unsigned int card, unsigned int device, snprintf(fn, sizeof(fn), "/dev/snd/pcmC%uD%u%c", card, device, flags & PCM_IN ? 'c' : 'p'); - fd = open(fn, O_RDWR); + if (flags & PCM_NONBLOCK) + fd = open(fn, O_RDWR | O_NONBLOCK); + else + fd = open(fn, O_RDWR); + if (fd < 0) { - fprintf(stderr, "cannot open device '%s'\n", fn); + fprintf(stderr, "cannot open device '%s': %s\n", fn, strerror(errno)); goto err_open; } @@ -1073,7 +1077,12 @@ struct pcm *pcm_open(unsigned int card, unsigned int device, flags & PCM_IN ? 'c' : 'p'); pcm->flags = flags; - pcm->fd = open(fn, O_RDWR); + + if (flags & PCM_NONBLOCK) + pcm->fd = open(fn, O_RDWR | O_NONBLOCK); + else + pcm->fd = open(fn, O_RDWR); + if (pcm->fd < 0) { oops(pcm, errno, "cannot open device '%s'", fn); return pcm; |