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/*
clsync - file tree sync utility based on inotify/kqueue
Copyright (C) 2014 Dmitry Yu Okunev <dyokunev@ut.mephi.ru> 0x8E30679C
This program 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 3 of the License, or
(at your option) any later version.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "common.h"
#include "calc.h"
#include "error.h"
#ifdef HAVE_MHASH
#include <mhash.h>
#endif
#ifndef HAVE_MHASH
/**
* @brief Calculated Adler32 value for char array
*
* @param[in] data Pointer to data
* @param[in] len Length of the data
*
* @retval uint32_t Adler32 value of data
*
*/
// Copied from http://en.wikipedia.org/wiki/Adler-32
uint32_t adler32_calc ( const unsigned char *const data, uint32_t len ) // where data is the location of the data in physical
{
// memory and len is the length of the data in bytes
/*
if (len&3)
warning("len [%i] & 3 == %i != 0. Wrong length (not a multiple of 4).", len, len&3);
*/
debug ( 70, "%p, %i", data, len );
const int MOD_ADLER = 65521;
uint32_t a = 1, b = 0;
uint32_t index;
// Process each byte of the data in order
for ( index = 0; index < len; ++index ) {
debug ( 80, "%5i: %02x %02x %02x", index, data[index], a, b );
a = ( a + data[index] ) % MOD_ADLER;
b = ( b + a ) % MOD_ADLER;
}
return ( b << 16 ) | a;
}
#endif
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