treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
[sfrench/cifs-2.6.git] / drivers / media / usb / gspca / sn9c2028.h
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 }