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/*
* Checksum functions
*
* Copyright (C) 2009-2018, Joachim Metz <joachim.metz@gmail.com>
*
* Refer to AUTHORS for acknowledgements.
*
* This software is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This software 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 Lesser General Public License
* along with this software. If not, see <http://www.gnu.org/licenses/>.
*/
#include <common.h>
#include <types.h>
#include "libfmapi_libcerror.h"
/* CRC-32 functions
* Based on RFC 1952
*/
/* Table of CRC-32 values of 8-bit values
*/
uint32_t libfmapi_checksum_crc32_table[ 256 ];
/* Value to indicate the CRC-32 table been computed
*/
int libfmapi_checksum_crc32_table_computed = 0;
/* Initializes the internal CRC-32 table
* The table speeds up the CRC-32 calculation
*/
void libfmapi_checksum_initialize_crc32_table(
void )
{
uint32_t checksum = 0;
uint32_t table_index = 0;
uint8_t bit_iterator = 0;
for( table_index = 0;
table_index < 256;
table_index++ )
{
checksum = (uint32_t) table_index;
for( bit_iterator = 0;
bit_iterator < 8;
bit_iterator++ )
{
if( checksum & 1 )
{
checksum = (uint32_t) 0xedb88320UL ^ ( checksum >> 1 );
}
else
{
checksum = checksum >> 1;
}
}
libfmapi_checksum_crc32_table[ table_index ] = checksum;
}
libfmapi_checksum_crc32_table_computed = 1;
}
/* Calculates the CRC-32 checksum of a buffer
* Returns 1 if successful or -1 on error
*/
int libfmapi_checksum_calculate_crc32(
uint32_t *checksum,
const uint8_t *buffer,
size_t size,
uint32_t initial_value,
libcerror_error_t **error )
{
static char *function = "libfmapi_checksum_calculate_crc32";
size_t buffer_offset = 0;
uint32_t table_index = 0;
if( checksum == NULL )
{
libcerror_error_set(
error,
LIBCERROR_ERROR_DOMAIN_ARGUMENTS,
LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,
"%s: invalid checksum.",
function );
return( -1 );
}
if( buffer == NULL )
{
libcerror_error_set(
error,
LIBCERROR_ERROR_DOMAIN_ARGUMENTS,
LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,
"%s: invalid buffer.",
function );
return( -1 );
}
if( size > (size_t) SSIZE_MAX )
{
libcerror_error_set(
error,
LIBCERROR_ERROR_DOMAIN_ARGUMENTS,
LIBCERROR_ARGUMENT_ERROR_VALUE_EXCEEDS_MAXIMUM,
"%s: invalid size value exceeds maximum.",
function );
return( -1 );
}
*checksum = initial_value ^ (uint32_t) 0xffffffffUL;
if( libfmapi_checksum_crc32_table_computed == 0 )
{
libfmapi_checksum_initialize_crc32_table();
}
for( buffer_offset = 0;
buffer_offset < size;
buffer_offset++ )
{
table_index = ( *checksum ^ buffer[ buffer_offset ] ) & 0x000000ffUL;
*checksum = libfmapi_checksum_crc32_table[ table_index ] ^ ( *checksum >> 8 );
}
*checksum ^= 0xffffffffUL;
return( 1 );
}
/* Calculates the weak CRC-32 checksum of a buffer
* Returns 1 if successful or -1 on error
*/
int libfmapi_checksum_calculate_weak_crc32(
uint32_t *checksum,
const uint8_t *buffer,
size_t size,
uint32_t initial_value,
libcerror_error_t **error )
{
static char *function = "libfmapi_checksum_calculate_weak_crc32";
size_t buffer_offset = 0;
uint32_t table_index = 0;
if( checksum == NULL )
{
libcerror_error_set(
error,
LIBCERROR_ERROR_DOMAIN_ARGUMENTS,
LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,
"%s: invalid checksum.",
function );
return( -1 );
}
if( buffer == NULL )
{
libcerror_error_set(
error,
LIBCERROR_ERROR_DOMAIN_ARGUMENTS,
LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,
"%s: invalid buffer.",
function );
return( -1 );
}
if( size > (size_t) SSIZE_MAX )
{
libcerror_error_set(
error,
LIBCERROR_ERROR_DOMAIN_ARGUMENTS,
LIBCERROR_ARGUMENT_ERROR_VALUE_EXCEEDS_MAXIMUM,
"%s: invalid size value exceeds maximum.",
function );
return( -1 );
}
*checksum = initial_value;
if( libfmapi_checksum_crc32_table_computed == 0 )
{
libfmapi_checksum_initialize_crc32_table();
}
for( buffer_offset = 0;
buffer_offset < size;
buffer_offset++ )
{
table_index = ( *checksum ^ buffer[ buffer_offset ] ) & 0x000000ffUL;
*checksum = libfmapi_checksum_crc32_table[ table_index ] ^ ( *checksum >> 8 );
}
return( 1 );
}
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