From: Takashi Iwai <tiwai@suse.de>
To: alsa-devel@alsa-project.org
Subject: [PATCH 4/5] ALSA: usb-audio: Factor out DSD bitrev copy function
Date: Tue, 1 Jun 2021 18:24:56 +0200 [thread overview]
Message-ID: <20210601162457.4877-5-tiwai@suse.de> (raw)
In-Reply-To: <20210601162457.4877-1-tiwai@suse.de>
Just minor code refactoring. Like DOP DSD code, it can be better in a
separate function for code readability.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/usb/pcm.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 8ee45f2e8dce..e26d37365f02 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -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)
--
2.26.2
next prev parent reply other threads:[~2021-06-01 16:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-01 16:24 [PATCH 0/5] ALSA: usb-audio: Delay account cleanup and latency reduction Takashi Iwai
2021-06-01 16:24 ` [PATCH 1/5] ALSA: usb-audio: Make snd_usb_pcm_delay() static Takashi Iwai
2021-06-01 16:24 ` [PATCH 2/5] ALSA: usb-audio: Pre-calculate buffer byte size Takashi Iwai
2021-06-01 16:24 ` [PATCH 3/5] ALSA: usb-audio: Refactoring delay account code Takashi Iwai
2021-06-01 16:24 ` Takashi Iwai [this message]
2021-06-01 16:24 ` [PATCH 5/5] ALSA: usb-audio: Reduce latency at playback start Takashi Iwai
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210601162457.4877-5-tiwai@suse.de \
--to=tiwai@suse.de \
--cc=alsa-devel@alsa-project.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).