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/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* Very simple 8-bit CRC function.
*/
#include "2sysincludes.h"
#include "2crc8.h"
/* Uses CRC-8 ITU version, with x^8 + x^2 + x + 1 polynomial.
Note that result will evaluate to zero for a buffer of all zeroes. */
uint8_t vb2_crc8(const void *vptr, uint32_t size)
{
const uint8_t *data = vptr;
unsigned crc = 0;
uint32_t i, j;
/* Calculate CRC-8 directly. A table-based algorithm would be faster,
but for only a few bytes it isn't worth the code size. */
for (j = size; j; j--, data++) {
crc ^= (*data << 8);
for(i = 8; i; i--) {
if (crc & 0x8000)
crc ^= (0x1070 << 3);
crc <<= 1;
}
}
return (uint8_t)(crc >> 8);
}
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