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5bdd00b9 TK |
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 | * | |
5bdd00b9 TK |
18 | */ |
19 | ||
d8fd9f56 VK |
20 | static const unsigned char sn9c2028_sof_marker[] = { |
21 | 0xff, 0xff, 0x00, 0xc4, 0xc4, 0x96, | |
22 | 0x00, | |
23 | 0x00, /* seq */ | |
24 | 0x00, | |
25 | 0x00, | |
26 | 0x00, /* avg luminance lower 8 bit */ | |
27 | 0x00, /* avg luminance higher 8 bit */ | |
28 | }; | |
5bdd00b9 TK |
29 | |
30 | static unsigned char *sn9c2028_find_sof(struct gspca_dev *gspca_dev, | |
31 | unsigned char *m, int len) | |
32 | { | |
33 | struct sd *sd = (struct sd *) gspca_dev; | |
34 | int i; | |
35 | ||
36 | /* Search for the SOF marker (fixed part) in the header */ | |
37 | for (i = 0; i < len; i++) { | |
d8fd9f56 VK |
38 | if ((m[i] == sn9c2028_sof_marker[sd->sof_read]) || |
39 | (sd->sof_read > 5)) { | |
5bdd00b9 | 40 | sd->sof_read++; |
d8fd9f56 VK |
41 | if (sd->sof_read == 11) |
42 | sd->avg_lum_l = m[i]; | |
43 | if (sd->sof_read == 12) | |
44 | sd->avg_lum = (m[i] << 8) + sd->avg_lum_l; | |
5bdd00b9 TK |
45 | if (sd->sof_read == sizeof(sn9c2028_sof_marker)) { |
46 | PDEBUG(D_FRAM, | |
47 | "SOF found, bytes to analyze: %u." | |
48 | " Frame starts at byte #%u", | |
49 | len, i + 1); | |
50 | sd->sof_read = 0; | |
51 | return m + i + 1; | |
52 | } | |
53 | } else { | |
54 | sd->sof_read = 0; | |
55 | } | |
56 | } | |
57 | ||
58 | return NULL; | |
59 | } |