1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0-or-later */
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * SN9C2028 common functions
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (C) 2009 Theodore Kilgore <kilgota@auburn,edu>
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Based closely upon the file gspca/pac_common.h
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun static const unsigned char sn9c2028_sof_marker[] = {
11*4882a593Smuzhiyun 0xff, 0xff, 0x00, 0xc4, 0xc4, 0x96,
12*4882a593Smuzhiyun 0x00,
13*4882a593Smuzhiyun 0x00, /* seq */
14*4882a593Smuzhiyun 0x00,
15*4882a593Smuzhiyun 0x00,
16*4882a593Smuzhiyun 0x00, /* avg luminance lower 8 bit */
17*4882a593Smuzhiyun 0x00, /* avg luminance higher 8 bit */
18*4882a593Smuzhiyun };
19*4882a593Smuzhiyun
sn9c2028_find_sof(struct gspca_dev * gspca_dev,unsigned char * m,int len)20*4882a593Smuzhiyun static unsigned char *sn9c2028_find_sof(struct gspca_dev *gspca_dev,
21*4882a593Smuzhiyun unsigned char *m, int len)
22*4882a593Smuzhiyun {
23*4882a593Smuzhiyun struct sd *sd = (struct sd *) gspca_dev;
24*4882a593Smuzhiyun int i;
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun /* Search for the SOF marker (fixed part) in the header */
27*4882a593Smuzhiyun for (i = 0; i < len; i++) {
28*4882a593Smuzhiyun if ((m[i] == sn9c2028_sof_marker[sd->sof_read]) ||
29*4882a593Smuzhiyun (sd->sof_read > 5)) {
30*4882a593Smuzhiyun sd->sof_read++;
31*4882a593Smuzhiyun if (sd->sof_read == 11)
32*4882a593Smuzhiyun sd->avg_lum_l = m[i];
33*4882a593Smuzhiyun if (sd->sof_read == 12)
34*4882a593Smuzhiyun sd->avg_lum = (m[i] << 8) + sd->avg_lum_l;
35*4882a593Smuzhiyun if (sd->sof_read == sizeof(sn9c2028_sof_marker)) {
36*4882a593Smuzhiyun gspca_dbg(gspca_dev, D_FRAM,
37*4882a593Smuzhiyun "SOF found, bytes to analyze: %u - Frame starts at byte #%u\n",
38*4882a593Smuzhiyun len, i + 1);
39*4882a593Smuzhiyun sd->sof_read = 0;
40*4882a593Smuzhiyun return m + i + 1;
41*4882a593Smuzhiyun }
42*4882a593Smuzhiyun } else {
43*4882a593Smuzhiyun sd->sof_read = 0;
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun }
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun return NULL;
48*4882a593Smuzhiyun }
49