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 * 18 */ 19 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 }; 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++) { 38 if ((m[i] == sn9c2028_sof_marker[sd->sof_read]) || 39 (sd->sof_read > 5)) { 40 sd->sof_read++; 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; 45 if (sd->sof_read == sizeof(sn9c2028_sof_marker)) { 46 gspca_dbg(gspca_dev, D_FRAM, 47 "SOF found, bytes to analyze: %u - Frame starts at byte #%u\n", 48 len, i + 1); 49 sd->sof_read = 0; 50 return m + i + 1; 51 } 52 } else { 53 sd->sof_read = 0; 54 } 55 } 56 57 return NULL; 58 } 59