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;
}
static void copy_play_buf(struct loopback_pcm *play,
struct loopback_pcm *capt,
unsigned int bytes)
{
struct snd_pcm_runtime *runtime = play->substream->runtime;
char *src = runtime->dma_area;
char *dst = capt->substream->runtime->dma_area;
unsigned int src_off = play->buf_pos;
unsigned int dst_off = capt->buf_pos;
unsigned int clear_bytes = 0;
/* check if playback is draining, trim the capture copy size
* when our pointer is at the end of playback ring buffer */
if (runtime->status->state == SNDRV_PCM_STATE_DRAINING &&
snd_pcm_playback_hw_avail(runtime) < runtime->buffer_size) {
snd_pcm_uframes_t appl_ptr, appl_ptr1, diff;
appl_ptr = appl_ptr1 = runtime->control->appl_ptr;
appl_ptr1 -= appl_ptr1 % runtime->buffer_size;
appl_ptr1 += play->buf_pos / play->pcm_salign;
if (appl_ptr < appl_ptr1)
appl_ptr1 -= runtime->buffer_size;
diff = (appl_ptr - appl_ptr1) * play->pcm_salign;
if (diff < bytes) {
clear_bytes = bytes - diff;
bytes = diff;
}
}
for (;;) {
unsigned int size = bytes;
if (src_off + size > play->pcm_buffer_size)
size = play->pcm_buffer_size - src_off;
if (dst_off + size > capt->pcm_buffer_size)
size = capt->pcm_buffer_size - dst_off;
memcpy(dst + dst_off, src + src_off, size);
capt->silent_size = 0;
bytes -= size;
if (!bytes)
break;
src_off = (src_off + size) % play->pcm_buffer_size;
dst_off = (dst_off + size) % capt->pcm_buffer_size;
}
if (clear_bytes > 0) {
clear_capture_buf(capt, clear_bytes);
capt->silent_size = 0;
}
}