drivers/media/usb/gspca/sn9c2028.h

   1 /*
   2  * SN9C2028 common functions
   3  *
   4  * Copyright (C) 2009 Theodore Kilgore <kilgota@auburn,edu>
   5  *
   6  * Based closely upon the file gspca/pac_common.h
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  *
  22  */
  23
  24 static const unsigned char sn9c2028_sof_marker[5] =
  25         { 0xff, 0xff, 0x00, 0xc4, 0xc4 };
  26
  27 static unsigned char *sn9c2028_find_sof(struct gspca_dev *gspca_dev,
  28                                         unsigned char *m, int len)
  29 {
  30         struct sd *sd = (struct sd *) gspca_dev;
  31         int i;
  32
  33         /* Search for the SOF marker (fixed part) in the header */
  34         for (i = 0; i < len; i++) {
  35                 if (m[i] == sn9c2028_sof_marker[sd->sof_read]) {
  36                         sd->sof_read++;
  37                         if (sd->sof_read == sizeof(sn9c2028_sof_marker)) {
  38                                 PDEBUG(D_FRAM,
  39                                         "SOF found, bytes to analyze: %u."
  40                                         " Frame starts at byte #%u",
  41                                         len, i + 1);
  42                                 sd->sof_read = 0;
  43                                 return m + i + 1;
  44                         }
  45                 } else {
  46                         sd->sof_read = 0;
  47                 }
  48         }
  49
  50         return NULL;
  51 }