From 3687acb3a93b3f8332de5a9fa7d99be4a665bbdd Mon Sep 17 00:00:00 2001 From: Anton Tananaev Date: Mon, 11 Jun 2012 20:38:46 +0400 Subject: Added meiligao protocol (fix #4) --- src/org/traccar/helper/Crc.java | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 src/org/traccar/helper/Crc.java (limited to 'src/org/traccar/helper') diff --git a/src/org/traccar/helper/Crc.java b/src/org/traccar/helper/Crc.java new file mode 100644 index 000000000..a0ad83e72 --- /dev/null +++ b/src/org/traccar/helper/Crc.java @@ -0,0 +1,40 @@ +/* + * Copyright 2012 Anton Tananaev (anton.tananaev@gmail.com) + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.traccar.helper; + +/** + * CRC functions + */ +public class Crc { + + public static int crc16Ccitt(byte[] bytes) { + int crc = 0xFFFF; // initial value + int polynomial = 0x1021; // 0001 0000 0010 0001 (0, 5, 12) + + for (byte b : bytes) { + for (int i = 0; i < 8; i++) { + boolean bit = ((b >> (7-i) & 1) == 1); + boolean c15 = ((crc >> 15 & 1) == 1); + crc <<= 1; + if (c15 ^ bit) crc ^= polynomial; + } + } + + crc &= 0xffff; + return crc; + } + +} -- cgit v1.2.3