/* Copyright (c) 2013 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.
 */

#include "crc8.h"

/**
 * Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial.  A table-based
 * algorithm would be faster, but for only a few bytes it isn't worth the code
 * size. */
uint8_t Crc8(const void *vptr, int len)
{
	const uint8_t *data = vptr;
	unsigned crc = 0;
	int i, j;

	for (j = len; j; j--, data++) {
		crc ^= (*data << 8);
		for(i = 8; i; i--) {
			if (crc & 0x8000)
				crc ^= (0x1070 << 3);
			crc <<= 1;
		}
	}

	return (uint8_t)(crc >> 8);
}