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

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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: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2021-06-01 18:24:56 +02:00
parent e8a8f09cb0
commit 4f08391799
1 changed files with 19 additions and 9 deletions
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28
sound/usb/pcm.c
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@ -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)