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/*
* Copyright 1996-2002 - Karl R. Hakimian and David Fries
*
* This file is part of datalink.
*
* Datalink is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Datalink is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with datalink (see COPYING); if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
/* crc lookup table */
static unsigned short int crc16_table[16] = {
0x0000, 0xCC01, 0xD801, 0x1400, 0xF001, 0x3C00, 0x2800, 0xE401,
0xA001, 0x6C00, 0x7800, 0xB401, 0x5000, 0x9C01, 0x8801, 0x4400
};
unsigned short int dl_docrc(unsigned char *data)
{
int i;
unsigned short int t;
unsigned short int crc = 0;
int l;
l = data[0] - 2;
for (i = 0; i < l; i++)
{
t = crc16_table[crc & 0xF];
crc = (crc >> 4) & 0x0FFF;
crc = crc ^ t ^ crc16_table[data[i] & 0xF];
/* upper 4 bits */
t = crc16_table[crc & 0xF];
crc = (crc >> 4) & 0x0FFF;
crc = crc ^ t ^ crc16_table[(data[i] >> 4) & 0xF];
}
data[l++] = crc >> 8;
data[l] = crc & 0xff;
return (crc);
}
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