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/*
Copyright (C) 2014 Matthias P. Braendli (http://www.opendigitalradio.org)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
firecode.c
Implement a FireCode CRC calculator
Authors:
Matthias P. Braendli <matthias@mpb.li>
*/
#include "firecode.h"
uint16_t firecode_crc(uint8_t* buf, size_t size)
{
int crc;
int gen_poly;
crc = 0x0000;
gen_poly = 0x782F; // 0111 1000 0010 1111 (16, 14, 13, 12, 11, 5, 3, 2, 1, 0)
for (size_t len = 0; len < size; len++) {
for (int i = 0x80; i != 0; i >>= 1) {
if ((crc & 0x8000) != 0) {
crc = (crc << 1) ^ gen_poly;
}
else {
crc = crc << 1;
}
if ((buf[len] & i) != 0) {
crc ^= gen_poly;
}
}
}
return crc & 0xFFFF;
}
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