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 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 21 * 22 */ 23 24 static const unsigned char sn9c2028_sof_marker[] = { 25 0xff, 0xff, 0x00, 0xc4, 0xc4, 0x96, 26 0x00, 27 0x00, /* seq */ 28 0x00, 29 0x00, 30 0x00, /* avg luminance lower 8 bit */ 31 0x00, /* avg luminance higher 8 bit */ 32 }; 33 34 static unsigned char *sn9c2028_find_sof(struct gspca_dev *gspca_dev, 35 unsigned char *m, int len) 36 { 37 struct sd *sd = (struct sd *) gspca_dev; 38 int i; 39 40 /* Search for the SOF marker (fixed part) in the header */ 41 for (i = 0; i < len; i++) { 42 if ((m[i] == sn9c2028_sof_marker[sd->sof_read]) || 43 (sd->sof_read > 5)) { 44 sd->sof_read++; 45 if (sd->sof_read == 11) 46 sd->avg_lum_l = m[i]; 47 if (sd->sof_read == 12) 48 sd->avg_lum = (m[i] << 8) + sd->avg_lum_l; 49 if (sd->sof_read == sizeof(sn9c2028_sof_marker)) { 50 PDEBUG(D_FRAM, 51 "SOF found, bytes to analyze: %u." 52 " Frame starts at byte #%u", 53 len, i + 1); 54 sd->sof_read = 0; 55 return m + i + 1; 56 } 57 } else { 58 sd->sof_read = 0; 59 } 60 } 61 62 return NULL; 63 } 64