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Annotation of libelwix/src/pelco.c, revision 1.1

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 $
        !             6: * $Id: pelco.c,v 1.4 2012/07/04 14:53:43 misho Exp $
        !             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: 
        !            15: Copyright 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
        !            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:  */
        !            57: inline u_char
        !            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: }