From 9cc1cbd2b21afcd40091069d2f0a58565db18c15 Mon Sep 17 00:00:00 2001
From: Vitaly Litvak <vitavaque@gmail.com>
Date: Sun, 2 Oct 2016 08:17:43 +0300
Subject: Moved 'xor' checksum method to the utility class.

---
 src/org/traccar/helper/Checksum.java               |  9 +++++++++
 src/org/traccar/protocol/Jt600ProtocolDecoder.java | 12 ++----------
 2 files changed, 11 insertions(+), 10 deletions(-)

(limited to 'src/org/traccar')

diff --git a/src/org/traccar/helper/Checksum.java b/src/org/traccar/helper/Checksum.java
index 2a4b1191d..dde174545 100644
--- a/src/org/traccar/helper/Checksum.java
+++ b/src/org/traccar/helper/Checksum.java
@@ -194,6 +194,15 @@ public final class Checksum {
         return checksum;
     }
 
+    public static int xor(String string) {
+        byte[] bytes = string.getBytes(StandardCharsets.US_ASCII);
+        byte sum = 0;
+        for (byte b : bytes) {
+            sum ^= b;
+        }
+        return sum;
+    }
+
     public static String nmea(String msg) {
         int checksum = 0;
         for (byte b : msg.getBytes(StandardCharsets.US_ASCII)) {
diff --git a/src/org/traccar/protocol/Jt600ProtocolDecoder.java b/src/org/traccar/protocol/Jt600ProtocolDecoder.java
index 827d6fbb5..de4510d17 100644
--- a/src/org/traccar/protocol/Jt600ProtocolDecoder.java
+++ b/src/org/traccar/protocol/Jt600ProtocolDecoder.java
@@ -21,6 +21,7 @@ import org.jboss.netty.channel.Channel;
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.DeviceSession;
 import org.traccar.helper.BcdUtil;
+import org.traccar.helper.Checksum;
 import org.traccar.helper.DateBuilder;
 import org.traccar.helper.Parser;
 import org.traccar.helper.PatternBuilder;
@@ -267,7 +268,7 @@ public class Jt600ProtocolDecoder extends BaseProtocolDecoder {
             case "U02":
             case "U03":
                 int checkSum = parser.nextInt(16);
-                int calculatedCheckSum = checkSum(sentence.substring(1, sentence.length() - 3));
+                int calculatedCheckSum = Checksum.xor(sentence.substring(1, sentence.length() - 3));
                 if (checkSum == calculatedCheckSum) {
                     sendResponse(channel, "(S39)");
                     return position;
@@ -303,15 +304,6 @@ public class Jt600ProtocolDecoder extends BaseProtocolDecoder {
         return null;
     }
 
-    private byte checkSum(String sentence) {
-        byte[] bytes = sentence.getBytes(StandardCharsets.US_ASCII);
-        byte sum = 0;
-        for (byte b : bytes) {
-            sum ^= b;
-        }
-        return sum;
-    }
-
     private void sendResponse(Channel channel, String response) {
         if (channel != null) {
             channel.write(ChannelBuffers.copiedBuffer(response, StandardCharsets.US_ASCII));
-- 
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