lowlander / siddecompiler

Generate relocatable 6502 assembly source code from Commodore 64 .sid files

SIDdecompiler

Generate relocatable 6502 assembly source code from Commodore 64 .sid files

If you're that special kind of nerd that likes to play with other people's music drivers, then this is the tool for you!

This program takes a SID file and runs it through a 6502 emulator to produce a relocatable assembler source file.

Rob Hubbard tunes will be slightly better documented than others, with non-generic label names for data of known purpose.

The output is very simple and should work with most assemblers. I have tested it with 64tass.

Known issues

• The decompiler is very conservative when it comes to code and relocatable address operand generation. Data that looks like code in the disassembly has never been executed by the emulator and is left alone. Likewise, data that looks like address operands is also ignored if it has never been read.

• Does not currently handle tunes with timer based sample playback

• A lot of rips in HVSC consist of multiple music driver instances in a single file. Often, these are moved around in memory and are not very well handled by the address operand tracer.

• SIDs that set up IRQs or never return from init, are currently not supported

• Undocumented opcodes are only partially supported

Why???

This project started because I wanted to produce a Rob Hubbard plugin for the Prosonix SID tracker. The tracing emulator and address operand resolution became so effective that it works with a lot of other music drivers as well, so instead of HubbardDecompiler, it became SIDdecompiler. Hopefully others will find it useful too.

Thanks to

• Geir Tjelta for encouragement and debugging assistance

• Lasse Öörni for "siddump", from which my 6502 emulator is based

• Groepaz for the initial gnu Makefile and Visual Studio project dumper script

Feedback and bug reports are welcome, either on csdb (https://csdb.dk/release/?id=159804) or [email protected]