/*
 * Copyright 2013 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.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.FrameDecoder;

public class AplicomFrameDecoder extends FrameDecoder {

    @Override
    protected Object decode(
            ChannelHandlerContext ctx, Channel channel, ChannelBuffer buf) throws Exception {

        // Skip Alive message
        while (buf.readable() && Character.isDigit(buf.getByte(buf.readerIndex()))) {
            buf.readByte();
        }

        // Check minimum length
        if (buf.readableBytes() < 11) {
            return null;
        }

        // Read flags
        int version = buf.getUnsignedByte(buf.readerIndex() + 1);
        int offset = 1 + 1 + 3;
        if ((version & 0x80) != 0) {
            offset += 4;
        }

        // Get data length
        int length = buf.getUnsignedShort(buf.readerIndex() + offset);
        offset += 2;
        if ((version & 0x40) != 0) {
            offset += 3;
        }
        length += offset; // add header

        // Return buffer
        if (buf.readableBytes() >= length) {
            return buf.readBytes(length);
        }

        return null;
    }

}

@@ -15,16 +15,23 @@
 ht 2013 
+- 2018 
 Anton Ta
@@ -669,33 +669,26 @@
 ;%0D%0A%0D%0Aimport 
+i
 o
-rg.jboss
 .netty.buffe
@@ -693,81 +693,27 @@
 fer.
-ChannelBuffer;%0D%0Aimport org.jboss.netty.channel.Channel;%0D%0Aimport org.jboss
+ByteBuf;%0D%0Aimport io
 .net
@@ -758,17 +758,10 @@
 ort 
+i
 o
-rg.jboss
 .net
@@ -781,18 +781,20 @@
 dec.
-frame.Fram
+ByteToMessag
 eDec
@@ -802,16 +802,42 @@
 der;%0D%0A%0D%0A
+import java.util.List;%0D%0A%0D%0A
 public c
@@ -869,20 +869,28 @@
 extends 
-Fram
+ByteToMessag
 eDecoder
@@ -928,22 +928,20 @@
 ted 
-Object
+void
  decode(
 %0D%0A  
@@ -936,30 +936,16 @@
  decode(
-%0D%0A            
 ChannelH
@@ -967,42 +967,37 @@
 tx, 
-Channel channel, ChannelBuffer buf
+ByteBuf buf, List%3CObject%3E out
 ) th
@@ -1062,25 +1062,27 @@
  while (buf.
-r
+isR
 eadable() &&
@@ -1266,29 +1266,24 @@
       return
- null
 ;%0D%0A        %7D
@@ -1810,23 +1810,24 @@
         
-return 
+out.add(
 buf.read
@@ -1839,16 +1839,17 @@
 (length)
+)
 ;%0D%0A     
@@ -1857,32 +1857,8 @@
   %7D%0D
-%0A%0D%0A        return null;%0D
 %0A   

Migrate Aplicom frame decoder