From ba4af96c2b771e3984887de0a4d2d7338aed1270 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Sat, 18 Jan 2014 19:07:39 +1300
Subject: Implement KHD protocol

---
 src/org/traccar/helper/ChannelBufferTools.java | 22 ++++++++++++++++++++++
 src/org/traccar/helper/Crc.java                |  8 ++++++++
 2 files changed, 30 insertions(+)

(limited to 'src/org/traccar/helper')

diff --git a/src/org/traccar/helper/ChannelBufferTools.java b/src/org/traccar/helper/ChannelBufferTools.java
index c0df86bcd..ef2ebc313 100644
--- a/src/org/traccar/helper/ChannelBufferTools.java
+++ b/src/org/traccar/helper/ChannelBufferTools.java
@@ -97,6 +97,28 @@ public class ChannelBufferTools {
         
         return result.toString();
     }
+    
+    /**
+     * 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;
+    }
+
 
     /**
      * Convert integer array to byte array
diff --git a/src/org/traccar/helper/Crc.java b/src/org/traccar/helper/Crc.java
index 84224a781..5a668f30a 100644
--- a/src/org/traccar/helper/Crc.java
+++ b/src/org/traccar/helper/Crc.java
@@ -136,6 +136,14 @@ public class Crc {
         }
         return (int) checksum.getValue();
     }
+
+    public static int xorChecksum(ByteBuffer buf) {
+        int checksum = 0;
+        for (int i = 0; i < buf.remaining(); i++) {
+            checksum ^= buf.get(i);
+        }
+        return checksum;
+    }
     
     public static String nmeaChecksum(String msg) {
         int checksum = 0;
-- 
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