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Annotation of libelwix/src/pelco.c, revision 1.4

1.1       misho       1: /*************************************************************************
                      2: * (C) 2010 AITNET ltd - Sofia/Bulgaria - <misho@aitbg.com>
                      3: *  by Michael Pounov <misho@openbsd-bg.org>
                      4: *
                      5: * $Author: misho $
1.4     ! misho       6: * $Id: pelco.c,v 1.3.20.1 2015/06/25 00:36:48 misho Exp $
1.1       misho       7: *
                      8: **************************************************************************
                      9: The ELWIX and AITNET software is distributed under the following
                     10: terms:
                     11: 
                     12: All of the documentation and software included in the ELWIX and AITNET
                     13: Releases is copyrighted by ELWIX - Sofia/Bulgaria <info@elwix.org>
                     14: 
1.4     ! misho      15: Copyright 2004 - 2015
1.1       misho      16:        by Michael Pounov <misho@elwix.org>.  All rights reserved.
                     17: 
                     18: Redistribution and use in source and binary forms, with or without
                     19: modification, are permitted provided that the following conditions
                     20: are met:
                     21: 1. Redistributions of source code must retain the above copyright
                     22:    notice, this list of conditions and the following disclaimer.
                     23: 2. Redistributions in binary form must reproduce the above copyright
                     24:    notice, this list of conditions and the following disclaimer in the
                     25:    documentation and/or other materials provided with the distribution.
                     26: 3. All advertising materials mentioning features or use of this software
                     27:    must display the following acknowledgement:
                     28: This product includes software developed by Michael Pounov <misho@elwix.org>
                     29: ELWIX - Embedded LightWeight unIX and its contributors.
                     30: 4. Neither the name of AITNET nor the names of its contributors
                     31:    may be used to endorse or promote products derived from this software
                     32:    without specific prior written permission.
                     33: 
                     34: THIS SOFTWARE IS PROVIDED BY AITNET AND CONTRIBUTORS ``AS IS'' AND
                     35: ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     36: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     37: ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     38: FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     39: DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     40: OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     41: HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     42: LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     43: OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     44: SUCH DAMAGE.
                     45: */
                     46: #include "global.h"
                     47: 
                     48: 
                     49: /*
                     50:  * crcPelco() - Calculate Pelco D/P CRC
                     51:  *
                     52:  * @ver = Pelco protocol version (Dd | Pp)
                     53:  * @pkt = Packet for calculate crc
                     54:  * return: crc for packet, if is 0 check and crc_GetErrno() == EINVAL
                     55:        Pelco protocol not supported
                     56:  */
1.2       misho      57: u_char
1.1       misho      58: crcPelco(u_char ver, u_char *pkt)
                     59: {
                     60:        register u_char i, crc;
                     61: 
                     62:        assert(pkt);
                     63: 
                     64:        switch (ver) {
                     65:                case 'D':
                     66:                case 'd':
                     67:                        for (i = 1, crc = 0; i < 6; crc += pkt[i++]);
                     68:                        crc %= 0x100;
                     69:                        break;
                     70:                case 'P':
                     71:                case 'p':
                     72:                        for (i = 1, crc = pkt[0]; i < 7; crc ^= pkt[i++]);
                     73:                        break;
                     74:                default:
                     75:                        crc = 0;
                     76:                        elwix_SetErr(EINVAL, "Invalid parameters!");
                     77:        }
                     78: 
                     79:        return crc;
                     80: }