ALSA: Add extra delay count in PCM
Takashi Iwai [Mon, 13 Oct 2008 01:07:14 +0000 (03:07 +0200)]
Added runtime->delay field to adjust the delayed samples for snd_pcm_delay().
Typically a hardware FIFO length is stored in this field, so that the
extra delay between hwptr and applptr can be computed.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/pcm.h
sound/core/pcm_native.c

index c172968..267effd 100644 (file)
@@ -270,6 +270,7 @@ struct snd_pcm_runtime {
        snd_pcm_uframes_t hw_ptr_base;  /* Position at buffer restart */
        snd_pcm_uframes_t hw_ptr_interrupt; /* Position at interrupt time */
        unsigned long hw_ptr_jiffies;   /* Time when hw_ptr is updated */
+       snd_pcm_sframes_t delay;        /* extra delay; typically FIFO size */
 
        /* -- HW params -- */
        snd_pcm_access_t access;        /* access mode */
index fc6f98e..cb769d4 100644 (file)
@@ -587,14 +587,15 @@ int snd_pcm_status(struct snd_pcm_substream *substream,
        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
                status->avail = snd_pcm_playback_avail(runtime);
                if (runtime->status->state == SNDRV_PCM_STATE_RUNNING ||
-                   runtime->status->state == SNDRV_PCM_STATE_DRAINING)
+                   runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
                        status->delay = runtime->buffer_size - status->avail;
-               else
+                       status->delay += runtime->delay;
+               } else
                        status->delay = 0;
        } else {
                status->avail = snd_pcm_capture_avail(runtime);
                if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)
-                       status->delay = status->avail;
+                       status->delay = status->avail + runtime->delay;
                else
                        status->delay = 0;
        }
@@ -2404,6 +2405,7 @@ static int snd_pcm_delay(struct snd_pcm_substream *substream,
                        n = snd_pcm_playback_hw_avail(runtime);
                else
                        n = snd_pcm_capture_avail(runtime);
+               n += runtime->delay;
                break;
        case SNDRV_PCM_STATE_XRUN:
                err = -EPIPE;