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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdint.h>
#include <nanohub/crc.h>
/* this implements crc32 as crc.h defines it. It is not a normal CRC by any measure, so be careful with it */
static const uint32_t crctab[] =
{
0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9,
0x130476DC ,0x17C56B6B ,0x1A864DB2 ,0x1E475005,
0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61,
0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD
};
static uint32_t crcOneWord(uint32_t crc, uint32_t data, int cnt)
{
uint32_t i;
crc = crc ^ data;
for (i = 0; i < cnt; i++)
crc = (crc << 4) ^ crctab[crc >> 28];
return crc;
}
uint32_t crc32(const void *buf, size_t size, uint32_t crc)
{
const uint32_t *data32 = (const uint32_t *)buf;
const uint8_t *data8;
uint32_t word, i;
// word by word crc32
for (i = 0; i < size / 4; i++)
crc = crcOneWord(crc, *data32++, 8);
data8 = (const uint8_t*)data32;
// zero pad last word if required
if (size & 0x3) {
for (i *= 4, word = 0; i < size; i++)
word |= (*data8++) << ((i & 0x3) * 8);
crc = crcOneWord(crc, word, 8);
}
return crc;
}
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