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libraw1394
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apply optimization patch from Pieter Palmers that removes modulo operator from high frequency isochronous code 

git-svn-id: svn://svn.linux1394.org/libraw1394/trunk@167 53a565d1-3bb7-0310-b661-cf11e63c67ab
This commit is contained in:
ddennedy 2006-05-09 04:27:38 +00:00
parent 45503d30d3
commit e4e2330837
1 changed files with 16 additions and 4 deletions
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20
src/iso.c
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@ -22,6 +22,18 @@
#include "kernel-raw1394.h"
#include "raw1394_private.h"
/* This implements
x = (x+1) % n
using a branch based implementation
*/
static inline int increment_and_wrap(int x, int n)
{
++x;
if (x >= n)
x = 0;
return x;
}
/* old ISO API - kept for backwards compatibility */
static int do_iso_listen(struct raw1394_handle *handle, int channel)
@ -328,9 +340,9 @@ static int _raw1394_iso_xmit_queue_packets(raw1394handle_t handle)
/* advance packet cursors and cycle counter */
stat->n_packets--;
handle->next_packet = (handle->next_packet + 1) % stat->config.buf_packets;
handle->next_packet = increment_and_wrap(handle->next_packet, stat->config.buf_packets);
if(stat->xmit_cycle != -1)
stat->xmit_cycle = (stat->xmit_cycle + 1) % 8000;
stat->xmit_cycle = increment_and_wrap(stat->xmit_cycle, 8000);
packets.n_packets++;
if(disp == RAW1394_ISO_DEFER) {
@ -416,9 +428,9 @@ int raw1394_iso_xmit_write(raw1394handle_t handle, unsigned char *data, unsigned
return -1;
stat->n_packets--;
handle->next_packet = (handle->next_packet + 1) % stat->config.buf_packets;
handle->next_packet = increment_and_wrap(handle->next_packet, stat->config.buf_packets);
if(stat->xmit_cycle != -1)
stat->xmit_cycle = (stat->xmit_cycle + 1) % 8000;
stat->xmit_cycle = increment_and_wrap(stat->xmit_cycle, 8000);
return 0;
}