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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
/**
* @author Peter Boros
* @date 2004/09/20
* @version $Id$
* @file checksum.h
* @brief Definition of Checksum class
*
*/
#pragma once
#include <inttypes.h>
#include <string.h>
namespace fsa {
// {{{ class Checksum
/**
* @class Checksum
* @brief Simple checksum class
*/
class Checksum {
public:
/**
* @brief Comupte 32-bit checksum value of an arbitrary buffer.
*
* @param buffer Pointer to the buffer.
* @param size Size of the buffer.
* @return 32-bit checksum value.
*/
static uint32_t compute(void *buffer, uint32_t size)
{
uint32_t checksum=0,rest=0,i=0;
char *buf = (char *)buffer;
for(i=0;i<(size>>2);i++){
uint32_t tmp;
memcpy(&tmp, buf, sizeof(uint32_t));
buf += sizeof(uint32_t);
checksum += tmp;
}
//@@@@@@BUG! should be if((size&3)>0) but that will break checksumming; postpone to next major .fsa format change
if(size&(3>0)){ // was if(size&3>0) but that generates a warning in GCC4
memcpy(&rest,(uint8_t*)buffer+4*i,size&3);
checksum+=rest;
}
return checksum;
}
};
// }}}
} // namespace fsa
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