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version 2.7

    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 1.3 2014/01/29 14:16:54 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 - 2014
   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: 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: }