1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * SN9C2028 common functions
4 *
5 * Copyright (C) 2009 Theodore Kilgore <kilgota@auburn,edu>
6 *
7 * Based closely upon the file gspca/pac_common.h
8 */
9
10 static const unsigned char sn9c2028_sof_marker[] = {
11 0xff, 0xff, 0x00, 0xc4, 0xc4, 0x96,
12 0x00,
13 0x00, /* seq */
14 0x00,
15 0x00,
16 0x00, /* avg luminance lower 8 bit */
17 0x00, /* avg luminance higher 8 bit */
18 };
19
20 static unsigned char *sn9c2028_find_sof(struct gspca_dev *gspca_dev,
21 unsigned char *m, int len)
22 {
23 struct sd *sd = (struct sd *) gspca_dev;
24 int i;
25
26 /* Search for the SOF marker (fixed part) in the header */
27 for (i = 0; i < len; i++) {
28 if ((m[i] == sn9c2028_sof_marker[sd->sof_read]) ||
29 (sd->sof_read > 5)) {
30 sd->sof_read++;
31 if (sd->sof_read == 11)
32 sd->avg_lum_l = m[i];
33 if (sd->sof_read == 12)
34 sd->avg_lum = (m[i] << 8) + sd->avg_lum_l;
35 if (sd->sof_read == sizeof(sn9c2028_sof_marker)) {
36 gspca_dbg(gspca_dev, D_FRAM,
37 "SOF found, bytes to analyze: %u - Frame starts at byte #%u\n",
38 len, i + 1);
39 sd->sof_read = 0;
40 return m + i + 1;
41 }
42 } else {
43 sd->sof_read = 0;
44 }
45 }
46
47 return NULL;
48 }