crc32.c

См. документацию.

/*
 *  CMSIS2000
 *  CMSIS-like sources for LPC2xxx series MCUs
 *
 *  (C) Copyright 2011-2012, Dmitriy Cherepanov, All Rights Reserved
 *
 *  Version: 0.0.7
 *  Date of the Last Update:  2013-03-04
 *  
 *  Permission is hereby granted, free of charge, to any person obtaining a copy
 *  of this software and associated documentation files (the "Software"), to
 *  deal in the Software without restriction, including without limitation the
 *  rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 *  sell copies of the Software, and to permit persons to whom the Software is
 *  furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included in
 *  all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 *  IN THE SOFTWARE.
 *
 *  Do not be lasy! For the latest version see http://irtos.sourceforge.net .
 *
 *  
#*/
/*----------------------------------------------------------------------------*/

/* three strategies
#include "2000/compiller/strategies.h"
-Os
-03 static
-03 dynamic
*/

#include <stdint.h>
#include <stddef.h>
#include "../crc32.h"


uint32_t crc32_update(uint32_t crc_in, uint8_t val8)
{
        uint_fast8_t i;
        uint32_t entry;
        uint32_t poly = 0xEDB88320L;

        entry = (crc_in ^ ((uint32_t) val8)) & 0xFF;
        for (i = 0; i < 8; i++) {
                if (entry & 1)
                    entry = (entry >> 1) ^ poly;
                else
                    entry >>= 1;
        }
    return ( ((crc_in>>8) & 0x00FFFFFF) ^ entry);
}

/*----------------------------------------------------------------------------*/
uint32_t crc32_no_comp (uint32_t curr_crc, const uint8_t *data8, size_t len)
{
        while (len-- > 0) {
                curr_crc = crc32_update(curr_crc, *data8);
                data8++ ;
        }
return ( curr_crc );
}
/*----------------------------------------------------------------------------*/
uint32_t crc32_copy (uint32_t curr_crc, const uint8_t *data8, size_t len)
{
        while (len-- != 0) {
                curr_crc = crc32_update(curr_crc, *data8);
                data8++ ;
        }
return ( curr_crc );
}