0,0 → 1,141 |
/* |
* Copyright (c) 2009 Lukas Mejdrech |
* All rights reserved. |
* |
* Redistribution and use in source and binary forms, with or without |
* modification, are permitted provided that the following conditions |
* are met: |
* |
* - Redistributions of source code must retain the above copyright |
* notice, this list of conditions and the following disclaimer. |
* - 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. |
* - 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. |
*/ |
|
/** @addtogroup net |
* @{ |
*/ |
|
/** @file |
* General CRC and checksum computation implementation. |
*/ |
|
#include <sys/types.h> |
|
#include "include/checksum.h" |
|
#define CRC_DIVIDER_BE 0x04C11DB7 |
|
#define CRC_DIVIDER_LE 0xEDB88320 |
|
/** IP checksum value for computed zero checksum. |
* Zero is returned as 0xFFFF (not flipped) |
*/ |
#define IP_CHECKSUM_ZERO 0xFFFFu |
|
uint32_t compute_crc32_le( uint32_t seed, uint8_t * data, size_t length ){ |
size_t index; |
|
while( length >= 8 ){ |
seed ^= ( * data ); |
for( index = 0; index < 8; ++ index ){ |
if( seed & 1 ){ |
seed = ( seed >> 1 ) ^ (( uint32_t ) CRC_DIVIDER_LE ); |
}else{ |
seed >>= 1; |
} |
} |
++ data; |
length -= 8; |
} |
if( length > 0 ){ |
seed ^= ( * data ) >> ( 8 - length ); |
for( index = 0; index < length; ++ index ){ |
if( seed & 1 ){ |
seed = ( seed >> 1 ) ^ (( uint32_t ) CRC_DIVIDER_LE ); |
}else{ |
seed >>= 1; |
} |
} |
length -= 8; |
} |
return seed; |
} |
|
uint32_t compute_crc32_be( uint32_t seed, uint8_t * data, size_t length ){ |
size_t index; |
|
while( length >= 8 ){ |
seed ^= ( * data ) << 24; |
for( index = 0; index < 8; ++ index ){ |
if( seed & 0x80000000 ){ |
seed = ( seed << 1 ) ^ (( uint32_t ) CRC_DIVIDER_BE ); |
}else{ |
seed <<= 1; |
} |
} |
++ data; |
length -= 8; |
} |
if( length > 0 ){ |
seed ^= (( * data ) & ( 0xFF << ( 8 - length ))) << 24; |
for( index = 0; index < length; ++ index ){ |
if( seed & 0x80000000 ){ |
seed = ( seed << 1 ) ^ (( uint32_t ) CRC_DIVIDER_BE ); |
}else{ |
seed <<= 1; |
} |
} |
length -= 8; |
} |
return seed; |
} |
|
uint32_t compute_checksum( uint32_t seed, uint8_t * data, size_t length ){ |
size_t index; |
|
// sum all the 16 bit fields |
for( index = 0; index + 1 < length; index += 2 ){ |
seed += ( data[ index ] << 8 ) + data[ index + 1 ]; |
} |
|
// last odd byte with zero padding |
if( index + 1 == length ){ |
seed += data[ index ] << 8; |
} |
|
return seed; |
} |
|
uint16_t compact_checksum( uint32_t sum ){ |
// shorten to the 16 bits |
while( sum >> 16 ) sum = ( sum & 0xFFFF ) + ( sum >> 16 ); |
|
return ( uint16_t ) sum; |
} |
|
uint16_t flip_checksum( uint16_t checksum ){ |
// flip, zero is returned as 0xFFFF (not flipped) |
return ( ~ checksum ) ? ( uint16_t ) ( ~ checksum ) : IP_CHECKSUM_ZERO; |
} |
|
uint16_t ip_checksum( uint8_t * data, size_t length ){ |
return flip_checksum( compact_checksum( compute_checksum( 0, data, length ))); |
} |
|
/** @} |
*/ |
Property changes: |
Added: svn:eol-style |
+native |
\ No newline at end of property |