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authorClemens Ladisch <clemens@ladisch.de>2005-08-25 05:10:05 -0400
committerJaroslav Kysela <perex@suse.cz>2005-08-30 02:47:34 -0400
commitc347e9fca710551f0def6a4d58505a6f4c0d87f6 (patch)
tree7a581a03569249bd70d9dbba96966d94d9e96a9e /sound/usb
parenta278655ff5d0c9d5eb34cf99f3a4c20da09eb09e (diff)
[ALSA] usb-audio: fix Emagic MIDI protocol handling
USB generic driver Emagic devices pad their packets not with 0xff bytes but with a 0xff byte followed by garbage, so we have to stop at the first such byte. Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Diffstat (limited to 'sound/usb')
-rw-r--r--sound/usb/usbmidi.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/sound/usb/usbmidi.c b/sound/usb/usbmidi.c
index d0d895df5375..5f19b494923e 100644
--- a/sound/usb/usbmidi.c
+++ b/sound/usb/usbmidi.c
@@ -594,17 +594,20 @@ static void snd_usbmidi_emagic_finish_out(snd_usb_midi_out_endpoint_t* ep)
594static void snd_usbmidi_emagic_input(snd_usb_midi_in_endpoint_t* ep, 594static void snd_usbmidi_emagic_input(snd_usb_midi_in_endpoint_t* ep,
595 uint8_t* buffer, int buffer_length) 595 uint8_t* buffer, int buffer_length)
596{ 596{
597 /* ignore padding bytes at end of buffer */ 597 int i;
598 while (buffer_length > 0 && buffer[buffer_length - 1] == 0xff) 598
599 --buffer_length; 599 /* FF indicates end of valid data */
600 for (i = 0; i < buffer_length; ++i)
601 if (buffer[i] == 0xff) {
602 buffer_length = i;
603 break;
604 }
600 605
601 /* handle F5 at end of last buffer */ 606 /* handle F5 at end of last buffer */
602 if (ep->seen_f5) 607 if (ep->seen_f5)
603 goto switch_port; 608 goto switch_port;
604 609
605 while (buffer_length > 0) { 610 while (buffer_length > 0) {
606 int i;
607
608 /* determine size of data until next F5 */ 611 /* determine size of data until next F5 */
609 for (i = 0; i < buffer_length; ++i) 612 for (i = 0; i < buffer_length; ++i)
610 if (buffer[i] == 0xf5) 613 if (buffer[i] == 0xf5)
@@ -671,6 +674,10 @@ static void snd_usbmidi_emagic_output(snd_usb_midi_out_endpoint_t* ep)
671 break; 674 break;
672 } 675 }
673 } 676 }
677 if (buf_free < ep->max_transfer && buf_free > 0) {
678 *buf = 0xff;
679 --buf_free;
680 }
674 ep->urb->transfer_buffer_length = ep->max_transfer - buf_free; 681 ep->urb->transfer_buffer_length = ep->max_transfer - buf_free;
675} 682}
676 683