/*
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017,
* 2018, 2019, 2020
* Jonathan Schleifer <js@nil.im>
*
* All rights reserved.
*
* This file is part of ObjFW. It may be distributed under the terms of the
* Q Public License 1.0, which can be found in the file LICENSE.QPL included in
* the packaging of this file.
*
* Alternatively, it may be distributed under the terms of the GNU General
* Public License, either version 2 or 3, which can be found in the file
* LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
* file.
*/
#include "config.h"
#import "crc16.h"
#define CRC16_MAGIC 0xA001
uint16_t
of_crc16(uint16_t crc, const void *bytes_, size_t length)
{
const unsigned char *bytes = bytes_;
for (size_t i = 0; i < length; i++) {
crc ^= bytes[i];
for (uint8_t j = 0; j < 8; j++)
crc = (crc >> 1) ^ (CRC16_MAGIC & (~(crc & 1) + 1));
}
return crc;
}