static void loopback_bytepos_update(struct loopback_pcm *dpcm,
unsigned int delta,
unsigned int cmd)
{
unsigned int count;
unsigned long last_pos;
last_pos = byte_pos(dpcm, dpcm->irq_pos);
dpcm->irq_pos += delta * dpcm->pcm_bps;
count = byte_pos(dpcm, dpcm->irq_pos) - last_pos;
if (!count)
return;
if (cmd == BYTEPOS_UPDATE_CLEAR)
clear_capture_buf(dpcm, count);
else if (cmd == BYTEPOS_UPDATE_COPY)
copy_play_buf(dpcm->cable->streams[SNDRV_PCM_STREAM_PLAYBACK],
dpcm->cable->streams[SNDRV_PCM_STREAM_CAPTURE],
count);
dpcm->buf_pos += count;
dpcm->buf_pos %= dpcm->pcm_buffer_size;
if (dpcm->irq_pos >= dpcm->period_size_frac) {
dpcm->irq_pos %= dpcm->period_size_frac;
dpcm->period_update_pending = 1;
}
}
static unsigned int loopback_pos_update(struct loopback_cable *cable)
{
struct loopback_pcm *dpcm_play =
cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
struct loopback_pcm *dpcm_capt =
cable->streams[SNDRV_PCM_STREAM_CAPTURE];
unsigned long delta_play = 0, delta_capt = 0;
unsigned int running, count1, count2;
unsigned long flags;
spin_lock_irqsave(&cable->lock, flags);
running = cable->running ^ cable->pause;
if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
delta_play = jiffies - dpcm_play->last_jiffies;
dpcm_play->last_jiffies += delta_play;
}
if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
delta_capt = jiffies - dpcm_capt->last_jiffies;
dpcm_capt->last_jiffies += delta_capt;
}
if (delta_play == 0 && delta_capt == 0)
goto unlock;
if (delta_play > delta_capt) {
count1 = bytepos_delta(dpcm_play, delta_play - delta_capt);
bytepos_finish(dpcm_play, count1);
delta_play = delta_capt;
} else if (delta_play < delta_capt) {
count1 = bytepos_delta(dpcm_capt, delta_capt - delta_play);
clear_capture_buf(dpcm_capt, count1);
bytepos_finish(dpcm_capt, count1);
delta_capt = delta_play;
}
if (delta_play == 0 && delta_capt == 0)
goto unlock;
/* note delta_capt == delta_play at this moment */
count1 = bytepos_delta(dpcm_play, delta_play);
count2 = bytepos_delta(dpcm_capt, delta_capt);
if (count1 < count2) {
dpcm_capt->last_drift = count2 - count1;
count1 = count2;
} else if (count1 > count2) {
dpcm_play->last_drift = count1 - count2;
}
copy_play_buf(dpcm_play, dpcm_capt, count1);
bytepos_finish(dpcm_play, count1);
bytepos_finish(dpcm_capt, count1);
unlock:
spin_unlock_irqrestore(&cable->lock, flags);
return running;
}
