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/*
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 * FreeModbus Libary: ATMega168 Port
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 * Copyright (C) 2006 Christian Walter <wolti@sil.at>
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 *
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 * This library is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * This library is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with this library; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
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 *
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 * File: $Id: mbcrc.c,v 1.2 2006/05/14 21:55:01 wolti Exp $
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 */
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/* ----------------------- System includes ----------------------------------*/
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#include <avr/pgmspace.h>
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/* ----------------------- Platform includes --------------------------------*/
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#include "port.h"
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static const PROGMEM UCHAR aucCRCHi[] = {
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    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
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    0x00, 0xC1, 0x81,
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    0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81,
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    0x40, 0x01, 0xC0,
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    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1,
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    0x81, 0x40, 0x01,
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    0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01,
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    0xC0, 0x80, 0x41,
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    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
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    0x00, 0xC1, 0x81,
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    0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80,
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    0x41, 0x01, 0xC0,
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    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
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    0x80, 0x41, 0x01,
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    0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00,
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    0xC1, 0x81, 0x40,
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    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
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    0x00, 0xC1, 0x81,
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    0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81,
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    0x40, 0x01, 0xC0,
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    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1,
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    0x81, 0x40, 0x01,
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    0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01,
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    0xC0, 0x80, 0x41,
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    0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
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    0x00, 0xC1, 0x81,
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    0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81,
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    0x40, 0x01, 0xC0,
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    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
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    0x80, 0x41, 0x01,
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    0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01,
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    0xC0, 0x80, 0x41,
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    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
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    0x00, 0xC1, 0x81,
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    0x40
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};
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static const PROGMEM UCHAR aucCRCLo[] = {
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    0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7,
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    0x05, 0xC5, 0xC4,
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    0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB,
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    0x0B, 0xC9, 0x09,
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    0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE,
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    0xDF, 0x1F, 0xDD,
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    0x1D, 0x1C, 0xDC, 0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2,
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    0x12, 0x13, 0xD3,
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    0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32,
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    0x36, 0xF6, 0xF7,
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    0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E,
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    0xFE, 0xFA, 0x3A,
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    0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B,
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    0x2A, 0xEA, 0xEE,
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    0x2E, 0x2F, 0xEF, 0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27,
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    0xE7, 0xE6, 0x26,
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    0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1,
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    0x63, 0xA3, 0xA2,
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    0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD,
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    0x6D, 0xAF, 0x6F,
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    0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8,
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    0xB9, 0x79, 0xBB,
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    0x7B, 0x7A, 0xBA, 0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4,
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    0x74, 0x75, 0xB5,
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    0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0,
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    0x50, 0x90, 0x91,
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    0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94,
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    0x54, 0x9C, 0x5C,
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    0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59,
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    0x58, 0x98, 0x88,
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    0x48, 0x49, 0x89, 0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D,
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    0x4D, 0x4C, 0x8C,
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    0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83,
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    0x41, 0x81, 0x80,
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    0x40
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};
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USHORT
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usMBCRC16( UCHAR * pucFrame, USHORT usLen )
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{
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    UCHAR           ucCRCHi = 0xFF;
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    UCHAR           ucCRCLo = 0xFF;
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    int             iIndex;
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    while( usLen-- )
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    {
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        iIndex = ucCRCLo ^ *( pucFrame++ );
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        ucCRCLo = ucCRCHi ^ pgm_read_byte( &aucCRCHi[iIndex] );
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        ucCRCHi = pgm_read_byte( &aucCRCLo[iIndex] );;
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    }
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    return ucCRCHi << 8 | ucCRCLo;
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}