code radio (delphi swing) skoda : i need 4 digits number

I need a compact Delphi routine that takes the serial information from a Skoda Swing radio and returns the correct unlock code, then simply presents that code on-screen. The focus is solely on the Swing variant (not Bolero or Columbus), so feel free to streamline the logic for that single model.

Core expectations
• Written in modern Object Pascal and ready to drop into a VCL or FMX project.
• No external DLLs—pure Delphi math / lookup is preferred.
• Once the algorithm resolves the 4-digit pin it must be shown to the user through a simple form or console write; nothing more complex.

Deliverables
1. Source unit (.pas) with well-commented decoding function.
2. Minimal demo project that shows the code in action.
3. Short read-me describing input requirements (e.g., where to read serial, expected format) and any test data used.

Acceptance
I will compile in Delphi 11, run the demo, enter a known Swing serial, and expect the displayed code to match my reference. If it does, we are done.

If you have past experience decoding Bolero or Columbus units, mention it—future extensions may follow—but keep this delivery strictly Swing + display.