| /* |
| * Pixart PAC207BCA / PAC73xx common functions |
| * |
| * Copyright (C) 2008 Hans de Goede <j.w.r.degoede@hhs.nl> |
| * Copyright (C) 2005 Thomas Kaiser thomas@kaiser-linux.li |
| * Copyleft (C) 2005 Michel Xhaard mxhaard@magic.fr |
| * |
| * V4L2 by Jean-Francois Moine <http://moinejf.free.fr> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| * |
| */ |
| |
| /* We calculate the autogain at the end of the transfer of a frame, at this |
| moment a frame with the old settings is being transmitted, and a frame is |
| being captured with the old settings. So if we adjust the autogain we must |
| ignore atleast the 2 next frames for the new settings to come into effect |
| before doing any other adjustments */ |
| #define PAC_AUTOGAIN_IGNORE_FRAMES 3 |
| |
| static const unsigned char pac_sof_marker[5] = |
| { 0xff, 0xff, 0x00, 0xff, 0x96 }; |
| |
| /* |
| The following state machine finds the SOF marker sequence |
| 0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream. |
| |
| +----------+ |
| | 0: START |<---------------\ |
| +----------+<-\ | |
| | \---/otherwise | |
| v 0xff | |
| +----------+ otherwise | |
| | 1 |--------------->* |
| | | ^ |
| +----------+ | |
| | | |
| v 0xff | |
| +----------+<-\0xff | |
| /->| |--/ | |
| | | 2 |--------------->* |
| | | | otherwise ^ |
| | +----------+ | |
| | | | |
| | v 0x00 | |
| | +----------+ | |
| | | 3 | | |
| | | |--------------->* |
| | +----------+ otherwise ^ |
| | | | |
| 0xff | v 0xff | |
| | +----------+ | |
| \--| 4 | | |
| | |----------------/ |
| +----------+ otherwise |
| | |
| v 0x96 |
| +----------+ |
| | FOUND | |
| +----------+ |
| */ |
| |
| static unsigned char *pac_find_sof(u8 *sof_read, |
| unsigned char *m, int len) |
| { |
| int i; |
| |
| /* Search for the SOF marker (fixed part) in the header */ |
| for (i = 0; i < len; i++) { |
| switch (*sof_read) { |
| case 0: |
| if (m[i] == 0xff) |
| *sof_read = 1; |
| break; |
| case 1: |
| if (m[i] == 0xff) |
| *sof_read = 2; |
| else |
| *sof_read = 0; |
| break; |
| case 2: |
| switch (m[i]) { |
| case 0x00: |
| *sof_read = 3; |
| break; |
| case 0xff: |
| /* stay in this state */ |
| break; |
| default: |
| *sof_read = 0; |
| } |
| break; |
| case 3: |
| if (m[i] == 0xff) |
| *sof_read = 4; |
| else |
| *sof_read = 0; |
| break; |
| case 4: |
| switch (m[i]) { |
| case 0x96: |
| /* Pattern found */ |
| PDEBUG(D_FRAM, |
| "SOF found, bytes to analyze: %u." |
| " Frame starts at byte #%u", |
| len, i + 1); |
| *sof_read = 0; |
| return m + i + 1; |
| break; |
| case 0xff: |
| *sof_read = 2; |
| break; |
| default: |
| *sof_read = 0; |
| } |
| break; |
| default: |
| *sof_read = 0; |
| } |
| } |
| |
| return NULL; |
| } |
