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authorMatthias P. Braendli <matthias.braendli@mpb.li>2014-11-09 11:33:11 +0100
committerMatthias P. Braendli <matthias.braendli@mpb.li>2014-11-09 11:33:11 +0100
commit639951285591ab6e8d1158e336a3f6c19477cc4f (patch)
tree40c6090f564539cd2bb201b85e4ffa53ddd4b880 /firecode.c
parent588a749b8544afce1824d9bcda80f2c5a44524e5 (diff)
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ETISnoop search for firecode
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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 (int 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;
+}
+