/* Copyright (c) 2011 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);
}