Thomas Gleixner | c942fdd | 2019-05-27 08:55:06 +0200 | [diff] [blame^] | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
Hans de Goede | 327c4ab | 2008-09-03 17:12:14 -0300 | [diff] [blame] | 2 | /* |
| 3 | * Pixart PAC207BCA / PAC73xx common functions |
| 4 | * |
| 5 | * Copyright (C) 2008 Hans de Goede <j.w.r.degoede@hhs.nl> |
| 6 | * Copyright (C) 2005 Thomas Kaiser thomas@kaiser-linux.li |
| 7 | * Copyleft (C) 2005 Michel Xhaard mxhaard@magic.fr |
| 8 | * |
| 9 | * V4L2 by Jean-Francois Moine <http://moinejf.free.fr> |
Hans de Goede | 327c4ab | 2008-09-03 17:12:14 -0300 | [diff] [blame] | 10 | */ |
| 11 | |
Hans de Goede | 8a5b2e9 | 2008-09-03 17:12:17 -0300 | [diff] [blame] | 12 | /* We calculate the autogain at the end of the transfer of a frame, at this |
Hans de Goede | 5fb2dde | 2010-02-17 11:59:19 -0300 | [diff] [blame] | 13 | moment a frame with the old settings is being captured and transmitted. So |
Mauro Carvalho Chehab | 3e4d8f4 | 2019-02-18 14:29:03 -0500 | [diff] [blame] | 14 | if we adjust the gain or exposure we must ignore at least the next frame for |
Hans de Goede | 5fb2dde | 2010-02-17 11:59:19 -0300 | [diff] [blame] | 15 | the new settings to come into effect before doing any other adjustments. */ |
| 16 | #define PAC_AUTOGAIN_IGNORE_FRAMES 2 |
Hans de Goede | 8a5b2e9 | 2008-09-03 17:12:17 -0300 | [diff] [blame] | 17 | |
Hans de Goede | 327c4ab | 2008-09-03 17:12:14 -0300 | [diff] [blame] | 18 | static const unsigned char pac_sof_marker[5] = |
| 19 | { 0xff, 0xff, 0x00, 0xff, 0x96 }; |
| 20 | |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 21 | /* |
| 22 | The following state machine finds the SOF marker sequence |
| 23 | 0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream. |
| 24 | |
| 25 | +----------+ |
| 26 | | 0: START |<---------------\ |
| 27 | +----------+<-\ | |
| 28 | | \---/otherwise | |
| 29 | v 0xff | |
| 30 | +----------+ otherwise | |
| 31 | | 1 |--------------->* |
| 32 | | | ^ |
| 33 | +----------+ | |
| 34 | | | |
| 35 | v 0xff | |
| 36 | +----------+<-\0xff | |
| 37 | /->| |--/ | |
| 38 | | | 2 |--------------->* |
| 39 | | | | otherwise ^ |
| 40 | | +----------+ | |
| 41 | | | | |
| 42 | | v 0x00 | |
| 43 | | +----------+ | |
| 44 | | | 3 | | |
| 45 | | | |--------------->* |
| 46 | | +----------+ otherwise ^ |
| 47 | | | | |
| 48 | 0xff | v 0xff | |
| 49 | | +----------+ | |
| 50 | \--| 4 | | |
| 51 | | |----------------/ |
| 52 | +----------+ otherwise |
| 53 | | |
| 54 | v 0x96 |
| 55 | +----------+ |
| 56 | | FOUND | |
| 57 | +----------+ |
| 58 | */ |
| 59 | |
Theodore Kilgore | c93396e | 2013-02-04 13:17:55 -0300 | [diff] [blame] | 60 | static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev, u8 *sof_read, |
Hans de Goede | 327c4ab | 2008-09-03 17:12:14 -0300 | [diff] [blame] | 61 | unsigned char *m, int len) |
| 62 | { |
Hans de Goede | 327c4ab | 2008-09-03 17:12:14 -0300 | [diff] [blame] | 63 | int i; |
| 64 | |
| 65 | /* Search for the SOF marker (fixed part) in the header */ |
| 66 | for (i = 0; i < len; i++) { |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 67 | switch (*sof_read) { |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 68 | case 0: |
| 69 | if (m[i] == 0xff) |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 70 | *sof_read = 1; |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 71 | break; |
| 72 | case 1: |
| 73 | if (m[i] == 0xff) |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 74 | *sof_read = 2; |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 75 | else |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 76 | *sof_read = 0; |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 77 | break; |
| 78 | case 2: |
| 79 | switch (m[i]) { |
| 80 | case 0x00: |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 81 | *sof_read = 3; |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 82 | break; |
| 83 | case 0xff: |
| 84 | /* stay in this state */ |
| 85 | break; |
| 86 | default: |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 87 | *sof_read = 0; |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 88 | } |
| 89 | break; |
| 90 | case 3: |
| 91 | if (m[i] == 0xff) |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 92 | *sof_read = 4; |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 93 | else |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 94 | *sof_read = 0; |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 95 | break; |
| 96 | case 4: |
| 97 | switch (m[i]) { |
| 98 | case 0x96: |
| 99 | /* Pattern found */ |
Joe Perches | 37d5efb | 2017-09-22 15:20:33 -0400 | [diff] [blame] | 100 | gspca_dbg(gspca_dev, D_FRAM, |
| 101 | "SOF found, bytes to analyze: %u - Frame starts at byte #%u\n", |
| 102 | len, i + 1); |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 103 | *sof_read = 0; |
Hans de Goede | 327c4ab | 2008-09-03 17:12:14 -0300 | [diff] [blame] | 104 | return m + i + 1; |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 105 | break; |
| 106 | case 0xff: |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 107 | *sof_read = 2; |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 108 | break; |
| 109 | default: |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 110 | *sof_read = 0; |
Hans de Goede | 327c4ab | 2008-09-03 17:12:14 -0300 | [diff] [blame] | 111 | } |
Marton Nemeth | e0d49e2 | 2009-10-05 05:41:30 -0300 | [diff] [blame] | 112 | break; |
| 113 | default: |
Marton Nemeth | a6b69e4 | 2009-11-02 08:05:51 -0300 | [diff] [blame] | 114 | *sof_read = 0; |
Hans de Goede | 327c4ab | 2008-09-03 17:12:14 -0300 | [diff] [blame] | 115 | } |
| 116 | } |
| 117 | |
| 118 | return NULL; |
| 119 | } |