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/*
* 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;
import org.jboss.netty.buffer.ChannelBuffer;
public final class ChannelBufferTools {
private ChannelBufferTools() {
}
/**
* Convert hex to integer (length in hex digits)
*/
public static int readHexInteger(ChannelBuffer buf, int length) {
int result = 0;
for (int i = 0; i < length / 2; i++) {
int b = buf.readUnsignedByte();
result *= 10;
result += b >>> 4;
result *= 10;
result += b & 0x0f;
}
if (length % 2 != 0) {
int b = buf.getUnsignedByte(buf.readerIndex());
result *= 10;
result += b >>> 4;
}
return result;
}
/**
* Read BCD coded coordinate (first byte has sign bit)
*/
public static double readCoordinate(ChannelBuffer buf) {
int b1 = buf.readUnsignedByte();
int b2 = buf.readUnsignedByte();
int b3 = buf.readUnsignedByte();
int b4 = buf.readUnsignedByte();
double value = (b2 & 0xf) * 10 + (b3 >> 4);
value += (((b3 & 0xf) * 10 + (b4 >> 4)) * 10 + (b4 & 0xf)) / 1000.0;
value /= 60;
value += ((b1 >> 4 & 0x7) * 10 + (b1 & 0xf)) * 10 + (b2 >> 4);
if ((b1 & 0x80) != 0) {
value = -value;
}
return value;
}
}
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