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