[alsa-devel] [PATCH] pcm: support for audio wallclock

[Pierre-Louis Bossart]

add new snd_pcm_status_get_htstamp_wallclk() routine to
query the audio timestamps read from the wallclock.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 include/pcm.h          |    1 +
 include/sound/asound.h |    7 ++++++-
 src/pcm/pcm.c          |   16 ++++++++++++++++
 3 files changed, 23 insertions(+), 1 deletions(-)

diff --git a/include/pcm.h b/include/pcm.h
index 4997557..325c0ea 100644
--- a/include/pcm.h
+++ b/include/pcm.h
@@ -858,6 +858,7 @@ void snd_pcm_status_get_trigger_tstamp(const snd_pcm_status_t *obj, snd_timestam
 void snd_pcm_status_get_trigger_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
 void snd_pcm_status_get_tstamp(const snd_pcm_status_t *obj, snd_timestamp_t *ptr);
 void snd_pcm_status_get_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
+void snd_pcm_status_get_htstamp_wallclk(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
 snd_pcm_sframes_t snd_pcm_status_get_delay(const snd_pcm_status_t *obj);
 snd_pcm_uframes_t snd_pcm_status_get_avail(const snd_pcm_status_t *obj);
 snd_pcm_uframes_t snd_pcm_status_get_avail_max(const snd_pcm_status_t *obj);
diff --git a/include/sound/asound.h b/include/sound/asound.h
index 07c03fa..c186fd6 100644
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -285,6 +285,7 @@ enum sndrv_pcm_subformat {
 #define SNDRV_PCM_INFO_JOINT_DUPLEX	0x00200000	/* playback and capture stream are somewhat correlated */
 #define SNDRV_PCM_INFO_SYNC_START	0x00400000	/* pcm support some kind of sync go */
 #define SNDRV_PCM_INFO_NO_PERIOD_WAKEUP	0x00800000	/* period wakeup can be disabled */
+#define SNDRV_PCM_INFO_HAS_WALL_CLOCK   0x01000000      /* has audio wall clock for audio/system time sync */
 
 enum sndrv_pcm_state {
 	SNDRV_PCM_STATE_OPEN = 0,	/* stream is open */
@@ -426,7 +427,10 @@ struct sndrv_pcm_status {
 	sndrv_pcm_uframes_t avail_max;	/* max frames available on hw since last status */
 	sndrv_pcm_uframes_t overrange;	/* count of ADC (capture) overrange detections from last status */
 	int suspended_state;		/* suspended stream state */
-	unsigned char reserved[60];	/* must be filled with zero */
+	union {
+		unsigned char reserved[60];	/* must be filled with zero */
+		struct timespec audio_tstamp;	/* audio wall clock timestamp */
+	} ext;
 };
 
 struct sndrv_pcm_mmap_status {
@@ -434,6 +438,7 @@ struct sndrv_pcm_mmap_status {
 	int pad1;			/* Needed for 64 bit alignment */
 	sndrv_pcm_uframes_t hw_ptr;	/* RO: hw ptr (0...boundary-1) */
 	struct timespec tstamp;		/* Timestamp */
+	struct timespec audio_tstamp;	/* audio wall clock timestamp */
 	int suspended_state;		/* RO: suspended stream state */
 };
 
diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index 18b43b3..2221865 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -6213,6 +6213,22 @@ void snd_pcm_status_get_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *p
 use_default_symbol_version(__snd_pcm_status_get_htstamp, snd_pcm_status_get_htstamp, ALSA_0.9.0rc8);
 
 /** 
+ * \brief Get "now" hi-res audio wallclock timestamp from a PCM status container
+ * \param obj pointer to #snd_pcm_status_t
+ * \param ptr Pointer to returned timestamp
+ */
+#ifndef DOXYGEN
+void INTERNAL(snd_pcm_status_get_htstamp_wallclk)(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr)
+#else
+void snd_pcm_status_get_htstamp_wallclk(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr)
+#endif
+{
+	assert(obj && ptr);
+	*ptr = obj->ext.audio_tstamp;
+}
+use_default_symbol_version(__snd_pcm_status_get_htstamp_wallclk, snd_pcm_status_get_htstamp_wallclk, ALSA_0.9.0rc8);  /* FIXME, no idea why this is needed */
+
+/**
  * \brief Get delay from a PCM status container (see #snd_pcm_delay)
  * \return Delay in frames
  *
-- 
1.7.6.5