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-rw-r--r--src/org/traccar/helper/Crc.java17
1 files changed, 17 insertions, 0 deletions
diff --git a/src/org/traccar/helper/Crc.java b/src/org/traccar/helper/Crc.java
index 5a668f30a..213d1192a 100644
--- a/src/org/traccar/helper/Crc.java
+++ b/src/org/traccar/helper/Crc.java
@@ -154,4 +154,21 @@ public class Crc {
return String.format("*%02x", checksum).toUpperCase();
}
+ public static String luhnChecksum(String s) {
+ int sum = 0;
+ boolean evenPosition = true;
+ for (int i = s.length() - 1; i >= 0; i--) {
+ int n = Integer.parseInt(s.substring(i, i + 1));
+ if (evenPosition) {
+ n *= 2;
+ if (n > 9) {
+ n = (n % 10) + 1;
+ }
+ }
+ sum += n;
+ evenPosition = !evenPosition;
+ }
+ return String.valueOf(10 - sum % 10);
+ }
+
}