From 02c1fb78a8b1681325ec01f49ae6ff6603825243 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Thu, 26 Apr 2012 19:34:10 +0000
Subject:

---
 src/org/traccar/protocol/XexunFrameDecoder.java | 92 +++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 src/org/traccar/protocol/XexunFrameDecoder.java

(limited to 'src/org/traccar/protocol/XexunFrameDecoder.java')

diff --git a/src/org/traccar/protocol/XexunFrameDecoder.java b/src/org/traccar/protocol/XexunFrameDecoder.java
new file mode 100644
index 000000000..86f409b3e
--- /dev/null
+++ b/src/org/traccar/protocol/XexunFrameDecoder.java
@@ -0,0 +1,92 @@
+/*
+ * 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.protocol;
+
+import org.jboss.netty.handler.codec.frame.FrameDecoder;
+import org.jboss.netty.channel.Channel;
+import org.jboss.netty.channel.ChannelHandlerContext;
+import org.jboss.netty.buffer.ChannelBuffer;
+
+public class XexunFrameDecoder extends FrameDecoder {
+
+    /**
+     * Find string in network buffer
+     */
+    private static Integer find(
+            ChannelBuffer buf,
+            Integer start,
+            Integer length,
+            String subString) {
+
+        int index = start;
+        boolean match;
+
+        for (; index < length; index++) {
+            match = true;
+
+            for (int i = 0; i < subString.length(); i++) {
+                char c = (char) buf.getByte(index + i);
+                if (c != subString.charAt(i)) {
+                    match = false;
+                    break;
+                }
+            }
+
+            if (match) {
+                return index;
+            }
+        }
+
+        return null;
+    }
+
+    protected Object decode(
+            ChannelHandlerContext ctx,
+            Channel channel,
+            ChannelBuffer buf) throws Exception {
+
+        // Check minimum length
+        int length = buf.readableBytes();
+        if (length < 100) {
+            return null;
+        }
+
+        // Find start
+        Integer beginIndex = find(buf, 0, length, "GPRMC");
+        if (beginIndex == null) {
+            return null;
+        }
+
+        // Find identifier
+        Integer idIndex = find(buf, beginIndex, length, "imei:");
+        if (idIndex == null) {
+            return null;
+        }
+
+        // Find end
+        Integer endIndex = find(buf, idIndex, length, ",");
+        if (endIndex == null) {
+            return null;
+        }
+
+        // Read buffer
+        buf.skipBytes(beginIndex);
+        ChannelBuffer frame = buf.readBytes(endIndex - beginIndex + 1);
+
+        return frame;
+    }
+
+}
-- 
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