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/*
* Copyright 2015 Anton Tananaev (anton@traccar.org)
*
* 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.protocol;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.FrameDecoder;
import java.nio.ByteOrder;
public class MxtFrameDecoder extends FrameDecoder {
@Override
protected Object decode(
ChannelHandlerContext ctx,
Channel channel,
ChannelBuffer buf) throws Exception {
if (buf.readableBytes() < 2) {
return null;
}
int index = buf.indexOf(buf.readerIndex() + 1, buf.writerIndex(), (byte) 0x04);
if (index != -1) {
ChannelBuffer result = ChannelBuffers.buffer(ByteOrder.LITTLE_ENDIAN, index + 1 - buf.readerIndex());
while (buf.readerIndex() <= index) {
int b = buf.readUnsignedByte();
if (b == 0x10) {
result.writeByte(buf.readUnsignedByte() - 0x20);
} else {
result.writeByte(b);
}
}
return result;
}
return null;
}
}
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