LXR linux/drivers/media/usb/gspca/sn9c2028.h

   1/* SPDX-License-Identifier: GPL-2.0-or-later */
   2/*
   3 * SN9C2028 common functions
   4 *
   5 * Copyright (C) 2009 Theodore Kilgore <kilgota@auburn,edu>
   6 *
   7 * Based closely upon the file gspca/pac_common.h
   8 */
   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