linux-2.6.33/snd_pcm_lib_read1() の履歴(No.1)

• 履歴一覧
• 差分 を表示
• 現在との差分 を表示
• ソース を表示
• linux-2.6.33/snd_pcm_lib_read1() へ行く。
  • 1 (2013-06-29 (土) 01:14:45)

---

参照元†

• linux-2.6.33/snd_pcm_lib_read()
• linux-2.6.33/snd_pcm_lib_readv()

説明†

• パス: linux-2.6.33/sound/core/pcm_lib.c

• FIXME: これは何？
  • 説明

引数†

• struct snd_pcm_substream *substream
  • linux-2.6.33/snd_pcm_substream
• unsigned long data
• snd_pcm_uframes_t size
  • linux-2.6.33/snd_pcm_uframes_t
• int nonblock
• transfer_f transfer
  • linux-2.6.33/transfer_f

返り値†

• snd_pcm_sframes_t
  • linux-2.6.33/snd_pcm_sframes_t

参考†

実装†

static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
					   unsigned long data,
					   snd_pcm_uframes_t size,
					   int nonblock,
					   transfer_f transfer)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	snd_pcm_uframes_t xfer = 0;
	snd_pcm_uframes_t offset = 0;
	int err = 0;

• • linux-2.6.33/snd_pcm_runtime

	if (size == 0)
		return 0;

	snd_pcm_stream_lock_irq(substream);

• • linux-2.6.33/snd_pcm_stream_lock_irq()

	switch (runtime->status->state) {
	case SNDRV_PCM_STATE_PREPARED:
		if (size >= runtime->start_threshold) {
			err = snd_pcm_start(substream);
			if (err < 0)
				goto _end_unlock;
		}

• • linux-2.6.33/SNDRV_PCM_STATE_PREPARED

• linux-2.6.33/snd_pcm_start()

		break;
	case SNDRV_PCM_STATE_DRAINING:
	case SNDRV_PCM_STATE_RUNNING:
	case SNDRV_PCM_STATE_PAUSED:
		break;

• • linux-2.6.33/SNDRV_PCM_STATE_DRAINING

• linux-2.6.33/SNDRV_PCM_STATE_RUNNING

• • linux-2.6.33/SNDRV_PCM_STATE_PAUSED

	case SNDRV_PCM_STATE_XRUN:
		err = -EPIPE;
		goto _end_unlock;

• • linux-2.6.33/SNDRV_PCM_STATE_XRUN

	case SNDRV_PCM_STATE_SUSPENDED:
		err = -ESTRPIPE;
		goto _end_unlock;

• • linux-2.6.33/SNDRV_PCM_STATE_SUSPENDED

	default:
		err = -EBADFD;
		goto _end_unlock;
	}

	while (size > 0) {
		snd_pcm_uframes_t frames, appl_ptr, appl_ofs;
		snd_pcm_uframes_t avail;
		snd_pcm_uframes_t cont;
		if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)
			snd_pcm_update_hw_ptr(substream);

• • linux-2.6.33/snd_pcm_update_hw_ptr()

		avail = snd_pcm_capture_avail(runtime);

• • linux-2.6.33/snd_pcm_capture_avail()

		if (!avail) {
			if (runtime->status->state ==
			    SNDRV_PCM_STATE_DRAINING) {
				snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
				goto _end_unlock;
			}

• • linux-2.6.33/snd_pcm_stop()

• linux-2.6.33/SNDRV_PCM_STATE_SETUP

			if (nonblock) {
				err = -EAGAIN;
				goto _end_unlock;
			}
			err = wait_for_avail_min(substream, &avail);
			if (err < 0)
				goto _end_unlock;
			if (!avail)
				continue; /* draining */

• • linux-2.6.33/wait_for_avail_min()

		}
		frames = size > avail ? avail : size;
		cont = runtime->buffer_size - runtime->control->appl_ptr % runtime->buffer_size;
		if (frames > cont)
			frames = cont;
		if (snd_BUG_ON(!frames)) {
			snd_pcm_stream_unlock_irq(substream);
			return -EINVAL;
		}

• runtime->control は snd_pcm_mmap_control 型
  • linux-2.6.33/snd_pcm_mmap_control
  • linux-2.6.33/snd_BUG_ON()
  • linux-2.6.33/snd_pcm_stream_unlock_irq()

		appl_ptr = runtime->control->appl_ptr;
		appl_ofs = appl_ptr % runtime->buffer_size;
		snd_pcm_stream_unlock_irq(substream);
		if ((err = transfer(substream, appl_ofs, data, offset, frames)) < 0)
			goto _end;
		snd_pcm_stream_lock_irq(substream);
		switch (runtime->status->state) {
		case SNDRV_PCM_STATE_XRUN:
			err = -EPIPE;
			goto _end_unlock;
		case SNDRV_PCM_STATE_SUSPENDED:
			err = -ESTRPIPE;
			goto _end_unlock;
		default:
			break;
		}
		appl_ptr += frames;
		if (appl_ptr >= runtime->boundary)
			appl_ptr -= runtime->boundary;
		runtime->control->appl_ptr = appl_ptr;
		if (substream->ops->ack)
			substream->ops->ack(substream);

		offset += frames;
		size -= frames;
		xfer += frames;
	}
 _end_unlock:
	snd_pcm_stream_unlock_irq(substream);
 _end:
	return xfer > 0 ? (snd_pcm_sframes_t)xfer : err;
}

コメント†