A C# library for manipulating x86-64 instructions and other concepts of the architecture. The focus so far is on decoding machine code, but it may grow into implementing tools (disassembler? debugger?) or having a more symbolic representation. The motivation is simply to formalize the concepts in my mind by coding them up.
Asmuth has a strong object model which favors immutability and minimizes both ambiguity and redundancy.Strong types are provided even for concepts as simple as an address size or a ModR/M byte. The instruction representation attempts to strike a good balance between being compact, supporting round-trips to its byte representation and providing a strong object model. Opcode encoding information is fully declarative.
One difficulty of x86-64 is the vast number of opcodes in existence, and the fact that the only official references are human-readable but non-machine-friendly PDFs by processor vendors (despite of the work by my friend Félix Cloutier to process them into HTML).
This project initially leveraged the NASM data files, which produced satisfyingly exhaustive opcode definitions but was complex due to their format, which is tailor-made for NASM's strings-to-bytes and bytes-to-strings operation.
I was later made aware of Intel's XED project and its data files, which are as close as there is to an official, machine-readable definition of the x86-64 instruction set. Their format, however, is that of a rule-based language meant to be used to generate code for an encoder or decoder. With some assumptions, it can still be used for our purposes.