1 files changed, 67 insertions, 0 deletions
diff --git a/src/org/traccar/protocol/TmgFrameDecoder.java b/src/org/traccar/protocol/TmgFrameDecoder.java
new file mode 100644
index 000000000..549c42466
--- /dev/null
+++ b/src/org/traccar/protocol/TmgFrameDecoder.java
@@ -0,0 +1,67 @@
+/*
+ * Copyright 2017 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.ChannelBufferIndexFinder;
+import org.jboss.netty.channel.Channel;
+import org.jboss.netty.channel.ChannelHandlerContext;
+import org.jboss.netty.handler.codec.frame.FrameDecoder;
+
+public class TmgFrameDecoder extends FrameDecoder {
+
+    private boolean isLetter(byte c) {
+        return c >= 'a' && c <= 'z';
+    }
+
+    @Override
+    protected Object decode(
+            ChannelHandlerContext ctx, Channel channel, ChannelBuffer buf) throws Exception {
+
+        int beginIndex = buf.indexOf(buf.readerIndex(), buf.writerIndex(), new ChannelBufferIndexFinder() {
+            @Override
+            public boolean find(ChannelBuffer buffer, int guessedIndex) {
+                if (buffer.getByte(guessedIndex) != (byte) '$' || buffer.writerIndex() - guessedIndex < 5) {
+                    return false;
+                }
+                if (buffer.getByte(guessedIndex + 4) == ','
+                        && isLetter(buffer.getByte(guessedIndex + 1))
+                        && isLetter(buffer.getByte(guessedIndex + 2))
+                        && isLetter(buffer.getByte(guessedIndex + 3))) {
+                    return true;
+                }
+                return false;
+            }
+        });
+
+        if (beginIndex >= 0) {
+
+            buf.readerIndex(beginIndex);
+
+            int endIndex = buf.indexOf(beginIndex, buf.writerIndex(), (byte) '\n');
+
+            if (endIndex >= 0) {
+                ChannelBuffer frame = buf.readBytes(endIndex - beginIndex);
+                buf.readByte(); // delimiter
+                return frame;
+            }
+
+        }
+
+        return null;
+    }
+
+}