1 files changed, 34 insertions, 0 deletions
diff --git a/research/sample-data/ip-butt-big-extract/testers/checksum_analyzer.py b/research/sample-data/ip-butt-big-extract/testers/checksum_analyzer.py
new file mode 100644
index 0000000..3760727
--- /dev/null
+++ b/research/sample-data/ip-butt-big-extract/testers/checksum_analyzer.py
@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+import sys
+
+
+def compute_checksum(data: bytes) -> int:
+    # PSA checksum excludes first 4 bytes ("MEL\0")
+    relevant = data[4:]
+    total = sum(relevant)
+    folded = (total & 0xFF) + (total >> 8)
+    return (~folded) & 0xFF
+
+
+def interactive_mode():
+    print("PSA Checksum Generator (Melody 0x3001 packets)")
+    print("Paste the hex payload WITHOUT the checksum byte. Type 'exit' to quit.")
+    while True:
+        user_input = input("Payload> ").strip()
+        if user_input.lower() in ("exit", "quit"):
+            break
+        try:
+            data = bytes.fromhex(user_input)
+            checksum = compute_checksum(data)
+            completed = data + bytes([checksum])
+            print("Checksum: {:02X}".format(checksum))
+            print("Full Packet: {}".format(completed.hex()))
+        except ValueError:
+            print("Invalid hex input. Try again.")
+
+
+if __name__ == "__main__":
+    if len(sys.argv) == 2 and sys.argv[1] == "--batch":
+        print("Batch mode not implemented. Run without arguments for interactive mode.")
+    else:
+        interactive_mode()