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1/* SPDX-License-Identifier: GPL-2.0-or-later */2/*3 * SN9C2028 common functions4 *5 * Copyright (C) 2009 Theodore Kilgore <kilgota@auburn,edu>6 *7 * Based closely upon the file gspca/pac_common.h8 */9 10static 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 20static 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}49