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pcm: handle negative values from snd_pcm_mmap_hw_avail

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Such negative values can happen when an underrun happens and xrun
detection is disabled. Another situation is if the device updated the
pointer before alsa-lib has a chance to detect the xrun.

The problem is that these negative values could propagate to the
snd_pcm_rewindable return value, where it is specified that negative
returns must be interpreted as error codes and not as negative amount of
samples.

Signed-off-by: Alexander E. Patrakov <patrakov@gmail.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Alexander E. Patrakov 2014-09-14 00:30:15 +06:00 • committed by Jaroslav Kysela
parent 9a43dc15b2
commit 78c804fc93
6 changed files with 23 additions and 7 deletions
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4
src/pcm/pcm_dshare.c
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@ -412,7 +412,7 @@ static int snd_pcm_dshare_pause(snd_pcm_t *pcm ATTRIBUTE_UNUSED, int enable ATTR
static snd_pcm_sframes_t snd_pcm_dshare_rewindable(snd_pcm_t *pcm)
{
return snd_pcm_mmap_playback_hw_avail(pcm);
return snd_pcm_mmap_playback_hw_rewindable(pcm);
}
static snd_pcm_sframes_t snd_pcm_dshare_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
@ -420,8 +420,6 @@ static snd_pcm_sframes_t snd_pcm_dshare_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t
snd_pcm_sframes_t avail;
avail = snd_pcm_dshare_rewindable(pcm);
if (avail < 0)
return 0;
if (frames > (snd_pcm_uframes_t)avail)
frames = avail;
snd_pcm_mmap_appl_backward(pcm, frames);