/*
* Copyright (c) 2008-2025 Jonathan Schleifer <js@nil.im>
*
* All rights reserved.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License version 3.0 only,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* version 3.0 for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* version 3.0 along with this program. If not, see
* <https://www.gnu.org/licenses/>.
*/
#include "config.h"
#import "OFCRC16.h"
static const uint16_t CRC16Magic = 0xA001;
uint16_t
_OFCRC16(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) ^ (CRC16Magic & (~(CRC & 1) + 1));
}
return CRC;
}