Nice, thanks! I appreciate seeing a bunch of the instruction definitions written in a serialisation format (e.g. https://github.com/OFFTKP/felix86/blob/master/counts/SSE2.js...) as opposed to C macros.

Those are tests, it seems. The actual sources are at https://github.com/OFFTKP/felix86/tree/master/src/felix86 and the disassembler is https://zydis.re.

The main x86 to RISC-V instruction mapping is in this file: https://github.com/OFFTKP/felix86/blob/master/src/felix86/v2...

That file is just testing I believe.