linux-2.6.33/snd_pcm_lib_ready_transfer()

参照元†

• 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 int hwoff
• unsigned long data
• unsigned int off
• snd_pcm_uframes_t frames
  • linux-2.6.33/snd_pcm_uframes_t

返り値†

• int

参考†

実装†

static int snd_pcm_lib_readv_transfer(struct snd_pcm_substream *substream,
				      unsigned int hwoff,
				      unsigned long data, unsigned int off,
				      snd_pcm_uframes_t frames)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	int err;
	void __user **bufs = (void __user **)data;
	int channels = runtime->channels;
	int c;

• • linux-2.6.33/snd_pcm_runtime

	if (substream->ops->copy) {
		for (c = 0; c < channels; ++c, ++bufs) {
			char __user *buf;
			if (*bufs == NULL)
				continue;
			buf = *bufs + samples_to_bytes(runtime, off);
			if ((err = substream->ops->copy(substream, c, hwoff, buf, frames)) < 0)
				return err;
		}

• • substream->ops は snd_pcm_ops 型のメンバ
  • linux-2.6.33/snd_pcm_ops

• linux-2.6.33/samples_to_bytes()

	} else {
		snd_pcm_uframes_t dma_csize = runtime->dma_bytes / channels;

• • linux-2.6.33/snd_pcm_uframes_t

		for (c = 0; c < channels; ++c, ++bufs) {
			char *hwbuf;
			char __user *buf;
			if (*bufs == NULL)
				continue;

			hwbuf = runtime->dma_area + (c * dma_csize) + samples_to_bytes(runtime, hwoff);
			buf = *bufs + samples_to_bytes(runtime, off);
			if (copy_to_user(buf, hwbuf, samples_to_bytes(runtime, frames)))
				return -EFAULT;
		}

• • linux-2.6.33/copy_to_user()

	}
	return 0;
}

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• katsuhiro

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