Commit 4f083917 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: usb-audio: Factor out DSD bitrev copy function 

Just minor code refactoring.  Like DOP DSD code, it can be better in a
separate function for code readability.

Link: https://lore.kernel.org/r/20210601162457.4877-5-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent e8a8f09c

sound/usb/pcm.c

+19 −9
Original line number Diff line number Diff line
@@ -1250,6 +1250,24 @@ static inline void fill_playback_urb_dsd_dop(struct snd_usb_substream *subs, 
	urb_ctx_queue_advance(subs, urb, queued);

}



/* copy bit-reversed bytes onto transfer buffer */

static void fill_playback_urb_dsd_bitrev(struct snd_usb_substream *subs,

					 struct urb *urb, unsigned int bytes)

{

	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;

	const u8 *src = runtime->dma_area;

	u8 *buf = urb->transfer_buffer;

	int i, ofs = subs->hwptr_done;



	for (i = 0; i < bytes; i++) {

		*buf++ = bitrev8(src[ofs]);

		if (++ofs >= subs->buffer_bytes)

			ofs = 0;

	}



	urb_ctx_queue_advance(subs, urb, bytes);

}



static void copy_to_urb(struct snd_usb_substream *subs, struct urb *urb,

			int offset, int stride, unsigned int bytes)

{
@@ -1360,15 +1378,7 @@ static void prepare_playback_urb(struct snd_usb_substream *subs, 
		fill_playback_urb_dsd_dop(subs, urb, bytes);

	} else if (unlikely(ep->cur_format == SNDRV_PCM_FORMAT_DSD_U8 &&

			   subs->cur_audiofmt->dsd_bitrev)) {

		/* bit-reverse the bytes */

		u8 *buf = urb->transfer_buffer;

		for (i = 0; i < bytes; i++) {

			int idx = (subs->hwptr_done + i) % subs->buffer_bytes;



			buf[i] = bitrev8(runtime->dma_area[idx]);

		}



		urb_ctx_queue_advance(subs, urb, bytes);

		fill_playback_urb_dsd_bitrev(subs, urb, bytes);

	} else {

		/* usual PCM */

		if (!subs->tx_length_quirk)