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ALSA: pcm - Fix delta calculation at boundary overlap 

When the hw_ptr_interrupt reaches the boundary, it must check whether
the hw_base was already lapped and corret the delta value appropriately.

Also, rebasing the hw_ptr needs a correction because buffer_size isn't
always aligned to period_size.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2009-03-19 10:08:49 +01:00
parent 5f513e1197
commit ded652f702
1 changed files with 7 additions and 2 deletions
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9
sound/core/pcm_lib.c
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@ -221,8 +221,11 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
new_hw_ptr = hw_base + pos;
hw_ptr_interrupt = runtime->hw_ptr_interrupt + runtime->period_size;
delta = new_hw_ptr - hw_ptr_interrupt;
if (hw_ptr_interrupt == runtime->boundary)
hw_ptr_interrupt = 0;
if (hw_ptr_interrupt >= runtime->boundary) {
hw_ptr_interrupt %= runtime->boundary;
if (!hw_base) /* hw_base was already lapped; recalc delta */
delta = new_hw_ptr - hw_ptr_interrupt;
}
if (delta < 0) {
delta += runtime->buffer_size;
if (delta < 0) {
@ -233,6 +236,8 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
(long)hw_ptr_interrupt);
/* rebase to interrupt position */
hw_base = new_hw_ptr = hw_ptr_interrupt;
/* align hw_base to buffer_size */
hw_base -= hw_base % runtime->buffer_size;
delta = 0;
} else {
hw_base += runtime->buffer_size;