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[] = {
25 0xff, 0xff, 0x00, 0xc4, 0xc4, 0x96,
26 0x00,
27 0x00, /* seq */
28 0x00,
29 0x00,
30 0x00, /* avg luminance lower 8 bit */
31 0x00, /* avg luminance higher 8 bit */
32 };
33
sn9c2028_find_sof(struct gspca_dev * gspca_dev,unsigned char * m,int len)34 static unsigned char *sn9c2028_find_sof(struct gspca_dev *gspca_dev,
35 unsigned char *m, int len)
36 {
37 struct sd *sd = (struct sd *) gspca_dev;
38 int i;
39
40 /* Search for the SOF marker (fixed part) in the header */
41 for (i = 0; i < len; i++) {
42 if ((m[i] == sn9c2028_sof_marker[sd->sof_read]) ||
43 (sd->sof_read > 5)) {
44 sd->sof_read++;
45 if (sd->sof_read == 11)
46 sd->avg_lum_l = m[i];
47 if (sd->sof_read == 12)
48 sd->avg_lum = (m[i] << 8) + sd->avg_lum_l;
49 if (sd->sof_read == sizeof(sn9c2028_sof_marker)) {
50 PDEBUG(D_FRAM,
51 "SOF found, bytes to analyze: %u."
52 " Frame starts at byte #%u",
53 len, i + 1);
54 sd->sof_read = 0;
55 return m + i + 1;
56 }
57 } else {
58 sd->sof_read = 0;
59 }
60 }
61
62 return NULL;
63 }
64