diff options
| -rw-r--r-- | include/tinyalsa/mixer.h | 1 | ||||
| -rw-r--r-- | src/mixer.c | 21 |
2 files changed, 22 insertions, 0 deletions
diff --git a/include/tinyalsa/mixer.h b/include/tinyalsa/mixer.h index faeb957..6cd914a 100644 --- a/include/tinyalsa/mixer.h +++ b/include/tinyalsa/mixer.h @@ -136,6 +136,7 @@ int mixer_ctl_get_range_min(const struct mixer_ctl *ctl); int mixer_ctl_get_range_max(const struct mixer_ctl *ctl); +int mixer_consume_event(struct mixer *mixer); #if defined(__cplusplus) } /* extern "C" */ #endif diff --git a/src/mixer.c b/src/mixer.c index 1c9e63b..c8c6c2a 100644 --- a/src/mixer.c +++ b/src/mixer.c @@ -535,6 +535,27 @@ int mixer_wait_event(struct mixer *mixer, int timeout) } } +/** Consume a mixer event. + * If mixer_subscribe_events has been called, + * mixer_wait_event will identify when a control value has changed. + * This function will clear a single event from the mixer so that + * further events can be alerted. + * + * @param mixer A mixer handle. + * @returns 0 on success. -errno on failure. + * @ingroup libtinyalsa-mixer + */ +int mixer_consume_event(struct mixer *mixer) { + struct snd_ctl_event ev; + ssize_t count = read(mixer->fd, &ev, sizeof(ev)); + // Exporting the actual event would require exposing snd_ctl_event + // via the header file, and all associated structs. + // The events generally tell you exactly which value changed, + // but reading values you're interested isn't hard and simplifies + // the interface greatly. + return (count >= 0) ? 0 : -errno; +} + static unsigned int mixer_grp_get_count(struct mixer_ctl_group *grp) { if (!grp) |