1 files changed, 8 insertions, 0 deletions
diff --git a/src/main/java/org/traccar/helper/Checksum.java b/src/main/java/org/traccar/helper/Checksum.java
index adfa697c5..d41dc2992 100644
--- a/src/main/java/org/traccar/helper/Checksum.java
+++ b/src/main/java/org/traccar/helper/Checksum.java
@@ -168,6 +168,14 @@ public final class Checksum {
         return checksum;
     }
 
+    public static int modulo256(ByteBuffer buf) {
+        int checksum = 0;
+        while (buf.hasRemaining()) {
+            checksum = (checksum + buf.get()) & 0xFF;
+        }
+        return checksum;
+    }
+
     public static String sum(String msg) {
         byte checksum = 0;
         for (byte b : msg.getBytes(StandardCharsets.US_ASCII)) {