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| author | Clemens Ladisch <clemens@ladisch.de> | 2006-01-12 08:19:21 +0100 |
|---|---|---|
| committer | Jaroslav Kysela <perex@suse.cz> | 2006-03-22 10:22:27 +0100 |
| commit | 9568f461e50c023e45ec702027bb1a5f60e443dc (patch) | |
| tree | 5c38356197de86514be184244eabc6f86a0154e5 /sound | |
| parent | 7c79b7682ee6318a8e47173b158846ed0edd8f1a (diff) | |
| download | lwn-9568f461e50c023e45ec702027bb1a5f60e443dc.tar.gz lwn-9568f461e50c023e45ec702027bb1a5f60e443dc.zip | |
[ALSA] usb-audio: factor out packet size calculation code
Modules: USB generic driver
Move the common packet size calculation code from
prepare_startup_playback_urb() and prepare_playback_urb() to a new
function.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/usb/usbaudio.c | 34 |
1 files changed, 14 insertions, 20 deletions
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c index d5013383fad7..f5aadb001986 100644 --- a/sound/usb/usbaudio.c +++ b/sound/usb/usbaudio.c @@ -475,6 +475,18 @@ static int retire_playback_sync_urb_hs(struct snd_usb_substream *subs, return 0; } +/* determine the number of frames in the next packet */ +static int snd_usb_audio_next_packet_size(struct snd_usb_substream *subs) +{ + if (subs->fill_max) + return subs->maxframesize; + else { + subs->phase = (subs->phase & 0xffff) + + (subs->freqm << subs->datainterval); + return min(subs->phase >> 16, subs->maxframesize); + } +} + /* * Prepare urb for streaming before playback starts. * @@ -492,16 +504,7 @@ static int prepare_startup_playback_urb(struct snd_usb_substream *subs, urb->dev = ctx->subs->dev; urb->number_of_packets = subs->packs_per_ms; for (i = 0; i < subs->packs_per_ms; ++i) { - /* calculate the size of a packet */ - if (subs->fill_max) - counts = subs->maxframesize; /* fixed */ - else { - subs->phase = (subs->phase & 0xffff) - + (subs->freqm << subs->datainterval); - counts = subs->phase >> 16; - if (counts > subs->maxframesize) - counts = subs->maxframesize; - } + counts = snd_usb_audio_next_packet_size(subs); urb->iso_frame_desc[i].offset = offs * stride; urb->iso_frame_desc[i].length = counts * stride; offs += counts; @@ -538,16 +541,7 @@ static int prepare_playback_urb(struct snd_usb_substream *subs, urb->number_of_packets = 0; spin_lock_irqsave(&subs->lock, flags); for (i = 0; i < ctx->packets; i++) { - /* calculate the size of a packet */ - if (subs->fill_max) - counts = subs->maxframesize; /* fixed */ - else { - subs->phase = (subs->phase & 0xffff) - + (subs->freqm << subs->datainterval); - counts = subs->phase >> 16; - if (counts > subs->maxframesize) - counts = subs->maxframesize; - } + counts = snd_usb_audio_next_packet_size(subs); /* set up descriptor */ urb->iso_frame_desc[i].offset = offs * stride; urb->iso_frame_desc[i].length = counts * stride; |