1 /*
2 * Pixart PAC207BCA / PAC73xx common functions
3 *
4 * Copyright (C) 2008 Hans de Goede <j.w.r.degoede@hhs.nl>
5 * Copyright (C) 2005 Thomas Kaiser thomas@kaiser-linux.li
6 * Copyleft (C) 2005 Michel Xhaard mxhaard@magic.fr
7 *
8 * V4L2 by Jean-Francois Moine <http://moinejf.free.fr>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 *
24 */
25
26 /* We calculate the autogain at the end of the transfer of a frame, at this
27 moment a frame with the old settings is being transmitted, and a frame is
28 being captured with the old settings. So if we adjust the autogain we must
29 ignore atleast the 2 next frames for the new settings to come into effect
30 before doing any other adjustments */
31 #define PAC_AUTOGAIN_IGNORE_FRAMES 3
32
33 static const unsigned char pac_sof_marker[5] =
34 { 0xff, 0xff, 0x00, 0xff, 0x96 };
35
36 static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev,
37 unsigned char *m, int len)
38 {
39 struct sd *sd = (struct sd *) gspca_dev;
40 int i;
41
42 /* Search for the SOF marker (fixed part) in the header */
43 for (i = 0; i < len; i++) {
44 if (m[i] == pac_sof_marker[sd->sof_read]) {
45 sd->sof_read++;
46 if (sd->sof_read == sizeof(pac_sof_marker)) {
47 PDEBUG(D_FRAM,
48 "SOF found, bytes to analyze: %u."
49 " Frame starts at byte #%u",
50 len, i + 1);
51 sd->sof_read = 0;
52 return m + i + 1;
53 }
54 } else {
55 sd->sof_read = 0;
56 }
57 }
58
59 return NULL;
60 }
61
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