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/* crc.c
* crc checksum generation and calculation functions: crc.c
*
* Copyright (c) 2007 by Intel Corporation.
*
* Author: Mike Harvey <michael.harvey@intel.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1999 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "crc.h"
#define WMAX_MAC_CRC32_POLYNOMIAL 0x04c11db7U /* polynomial used in calculating the CRC-32 checksum */
#define CCITT_X25_CRC16_POLYNOMIAL 0x1021 /* polynomial used in calculating the CRC-16 checksum */
#define WMAX_MAC_CRC8_POLYNOMIAL 0x07 /* polynomial used in calculating the CRC-8 checksum */
#define CRC32_INITIAL_VALUE 0xFFFFFFFF
#define CRC16_INITIAL_VALUE 0xFFFF
#ifndef STATIC_DATA
static guint8 crc8_table[256];
static guint32 crc32_table[256];
extern guint16 crc16_table[256];
/*
void wimax_mac_gen_crc32_table(void)
REQUIRES: The functions must be called only once to initialze CRC table
DESCRIPTION: Generate the table of CRC remainders
for all possible bytes
ARGS:
RETURNS:
SIDE EFFECTS:
*/
void wimax_mac_gen_crc32_table(void)
{
guint32 i, bit;
guint32 crc;
/* little-endian (reflected) algorithm */
for ( i = 0; i < G_N_ELEMENTS(crc32_table); i++ )
{
crc = ( i << 24 );
for ( bit = 0; bit < 8; bit++ )
{
if ( crc & 0x80000000U )
crc = ( crc << 1 ) ^ WMAX_MAC_CRC32_POLYNOMIAL;
else
crc = ( crc << 1 );
}
crc32_table[i] = crc;
}
}
/*
void wimax_mac_gen_crc8_table(void)
REQUIRES: The functions must be called only once to initialze CRC table
DESCRIPTION: Generate the table of CRC remainders
for all possible bytes
ARGS:
RETURNS:
SIDE EFFECTS:
*/
void wimax_mac_gen_crc8_table(void)
{
guint i, bit;
guint8 crc;
for ( i = 0; i < G_N_ELEMENTS(crc8_table); i++ )
{
crc = i;
for ( bit = 0; bit < 8; bit++ )
{
if ( crc & 0x80 )
crc = ( crc << 1 ) ^ WMAX_MAC_CRC8_POLYNOMIAL;
else
crc = ( crc << 1 );
}
crc8_table[i] = crc;
}
}
#endif
/*
guint32 wimax_mac_calc_crc32(guint8 *data, guint data_len)
REQUIRES: wimax_mac_gen_crc32_table() must be called before
DESCRIPTION: Calculate the 32-bit CRC from a given data block
ARGS: data - pointer to data
data_len - length of data (in bytes)
RETURNS: calculated crc32
SIDE EFFECTS:
*/
guint32 wimax_mac_calc_crc32(const guint8 *data, guint data_len)
{
guint32 crc=CRC32_INITIAL_VALUE;
guint i, j;
for ( j = 0; j < data_len; j++ )
{
i = ( (guint8)(crc>>24) ^ data[j] ) & 0xff;
crc = ( crc<<8 ) ^ crc32_table[i];
}
return ~crc;
}
/*
guint16 wimax_mac_calc_crc16(guint8 *data, guint data_len)
REQUIRES: crc16_table[] in crc_data.c
DESCRIPTION: Calculate the 16-bit CRC from a given data block
ARGS: data - pointer to data
data_len - length of data (in bytes)
RETURNS: calculated crc16
SIDE EFFECTS:
*/
guint16 wimax_mac_calc_crc16(const guint8 *data, guint data_len)
{
guint32 crc=CRC16_INITIAL_VALUE;
guint j;
for ( j = 0; j < data_len; j++ )
{
crc ^= data[j] << 8;
crc = (crc << 8) ^ crc16_table[(crc & 0xff00) >> 8];
}
crc ^= 0xFFFF; /* Invert the output. */
crc &= 0xFFFF;
return crc;
}
/*
guint8 wimax_mac_calc_crc8(guint8 *data, guint data_len)
REQUIRES: wimax_mac_gen_crc8_table() must be called before
DESCRIPTION: Calculate the 8-bit CRC from a given data block
ARGS: data - pointer to data
data_len - length of data (in bytes)
RETURNS: calculated crc8
SIDE EFFECTS:
*/
guint8 wimax_mac_calc_crc8(const guint8 *data, guint data_len)
{
guint8 crc=0;
guint i;
for(i = 0; i < data_len; i++)
{
crc = crc8_table[data[i]^crc];
}
return crc;
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local Variables:
* c-basic-offset: 2
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=2 tabstop=8 expandtab:
* :indentSize=2:tabSize=8:noTabs=true:
*/
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