jon-lipstate / ojitsu

Odin JIT Assembler

OJITSU

Work In Progress

Objective

• Runtime JIT Assembler for Odin
• Exportable as a C Header Library
• Static Library?
• Use fn-ptrs for runtime linking
• Multiplatform (Win/Nix) / MultiArch Support (x64, ARM)
• Export listing string/files for Debug use
• Encode Only, architecture is not intended for any form of decode

Design Goals

• Low-Level
  • No Abstractions over the asm
  • look & feel of writing nasm (to the extent possible)
• Ergonomic user-abi, procedures mimic asm mneumonics (mov(...)), engine can dismabiguate which specific asm call it is.
• Assembler holds an array of procedures, does not write entrypoints (eg global _start)
• Instructions are added as-needed to keep project size minimal (XED is 13 mb)
• • Possibly use subpackage imports by extension (?)

Todos/Ideas

• Use a Symbol/Relocation table in order to pre-compute instruction lengths

  • Permit ability to auto-insert nops for alignment

• Symbol Table also allows Forward Declared Labels

• Rust uses I/O declarations, good idea?

  • Pro is that it allows arch-independant proc declarations

  • Con is that it obfuscates register usage into an alias - Done with macros

    • Odin may not have a nice way to represent this

• use a cli on generated code to build minimal sized libs?

use std::arch::asm;
let i: u64 = 3;
let o: u64;
asm!("mov {0}, {1}","add {0}, 5",out(reg) o,in(reg) i,);
let mut x: u64 = 3;
asm!("add {0}, 5", inout(reg) x);