From 639951285591ab6e8d1158e336a3f6c19477cc4f Mon Sep 17 00:00:00 2001 From: "Matthias P. Braendli" Date: Sun, 9 Nov 2014 11:33:11 +0100 Subject: ETISnoop search for firecode --- firecode.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 firecode.c (limited to 'firecode.c') diff --git a/firecode.c b/firecode.c new file mode 100644 index 0000000..fd13dec --- /dev/null +++ b/firecode.c @@ -0,0 +1,50 @@ +/* + 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 . + + firecode.c + Implement a FireCode CRC calculator + + Authors: + Matthias P. Braendli +*/ + +#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; +} + -- cgit v1.2.3