/*
* FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
* Copyright (c) 2006 Christian Walter <wolti@sil.at>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* File: $Id: mbcrc.c,v 1.7 2007/02/18 23:50:27 wolti Exp $
*/
/*
* Assembly and non-table C versions of code are from Scott Dattalo,
* http://www.dattalo.com
* http://www.dattalo.com/technical/software/pic/crc.php
*/
/* ----------------------- Platform includes --------------------------------*/
#include "port.h"
//Set one of the defines below to 1, the rest to 0
#define TABLE_CRC 0 //Fast, uses 512 bytes of program rom
#define ASSEM_CRC 1 //Uses least resources, faster than C, unfathomable
#define C_CRC 0 //Less ROM than table, more portable than assem
#if C_CRC == 1
extern UCHAR CalcParity( UCHAR ucData );
#endif
#if TABLE_CRC == 1
//static const UCHAR aucCRCHi[] = {
rom char *aucCRCHi = {
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40
};
//static const UCHAR aucCRCLo[] = {
rom char *aucCRCLo = {
0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7,
0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E,
0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09, 0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9,
0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC,
0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32,
0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D,
0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A, 0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38,
0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF,
0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1,
0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4,
0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F, 0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB,
0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA,
0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0,
0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97,
0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C, 0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E,
0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89,
0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83,
0x41, 0x81, 0x80, 0x40
};
#endif
USHORT
usMBCRC16( UCHAR * pucFrame, USHORT usLen )
{
#if TABLE_CRC == 1
UCHAR ucCRCHi = 0xFF;
UCHAR ucCRCLo = 0xFF;
int iIndex;
while( usLen-- )
{
iIndex = ucCRCLo ^ *( pucFrame++ );
ucCRCLo = ( UCHAR )( ucCRCHi ^ (UCHAR)aucCRCHi[iIndex] );
ucCRCHi = (UCHAR)aucCRCLo[iIndex];
}
return ( USHORT )( ucCRCHi << 8 | ucCRCLo );
#endif
#if ASSEM_CRC == 1
UCHAR bCrcLo = 0xFF;
UCHAR bCrcHi = 0xFF;
UCHAR bCrcTemp;
UCHAR bIndex;
while( usLen-- )
{
bCrcTemp = *(pucFrame++);
asm
{
MOVF _bCrcTemp, W
XORWF _bCrcLo,W
MOVWF _bIndex
MOVF _bCrcHi,W
MOVWF _bCrcLo ;bCrcLo = crc >> 8
CLRF _bCrcTemp ;Holds the CRC pattern for the low byte
; CLRC ;
bcf _status, C
RRCF _bIndex,W ;W = 0.i7.i6.i5.i4.i3.i2.i1 C=i0
XORWF _bIndex,F ;F = 0i7.i7i6.i6i5.i5i4.i4i3.i3i2.i2i1.i1i0
RRCF _bCrcTemp,F ;t = i0.0.0.0.0.0.0.0 C=0
RRCF _bIndex,W ;W = 0.0i7.i7i6.i6i5.i5i4.i4i3.i3i2.i2i1 C=i1i0
MOVWF _bCrcHi ;bCrcHi = 0.0i7.i7i6.i6i5.i5i4.i4i3.i3i2.i2i1
RRCF _bCrcTemp,F ;t = i1i0.i0.0.0.0.0.0.0 C=0
RLCF _bIndex,F ;W = i7i6.i6i5.i5i4.i4i3.i3i2.i2i1.i1i0.0 C=i7
XORWF _bIndex,F ;F = X.X.i7i6i5i4.X.X.X.i3i2i1i0.X
SWAPF _bIndex,W ;F = X.X.i3i2i1i0.X.X.X.i7i6i5i4.X
XORWF _bIndex,F ;F = X.X.P.X.X.X.P.X where P= parity(bIndex)
; at this point, the parity of the bIndex byte is now at bits 1 and 5 of bIndex.
MOVF _bCrcTemp,W ;W = i1i0.i0.0.0.0.0.0.0
BTFSC _bIndex,1 ;If P==1
XORLW 1 ;W = i1i0.i0.0.0.0.0.0.P
XORWF _bCrcLo,F ;bCrcLo = (crc>>8) ^ i1i0.i0.0.0.0.0.0.P
MOVLW 0xC0
BTFSC _bIndex,1
XORWF _bCrcHi,F ;bCrcHi = P.Pi7.i7i6.i6i5.i5i4.i4i3.i3i2.i2i1
}
}
return ( USHORT )( bCrcHi << 8 | bCrcLo );
#endif
#if C_CRC == 1
USHORT iNum;
USHORT pNum;
USHORT usCRC = 0xFFFF;
while( usLen-- )
{
iNum = (usCRC ^ *(pucFrame++)) & 0xff;
pNum = 0x0000;
if( CalcParity((UCHAR)iNum) == 1)
{
pNum = 0xC001;
}
iNum = iNum << 6;
usCRC = pNum ^ (usCRC>>8) ^ iNum ^ (iNum<<1);
}
return usCRC;
#endif
}
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