orange

orange

A virtual machine with a custom ISA. Named after my favorite color because I can.

About

This repository features an assembler and a virtual machine for assembling and then running programs written in assembly. The instruction set architecture is described in ISA.md.

Why?

While taking an introductory computer architecture class, I became interested in exploring more advanced assemblers and simulators than the ones that we were learning about and creating in class.

The ISA for orange is inspired by "LEGv8", a subset of ARMv8 (hence the name), which we discuss in EECS 370. I plan to expand on the ISA to add more interesting features like built-in stack management.

Usage

To assemble a program, run the package located in ./cmd/orangeasm. To run a program, run the package located in ./cmd/orangevm. To link multiple object files, run the package located in ./cmd/orangelinker.

If you want to assemble a standalone program (e.g. no linking), use ./orangeasm --executable [input file] [output file].

Examples

• multiplication.orange
  • Multiplies two 32-bit numbers using grade-school multiplication algorithm
• string.orange
  • Traversal of a null-terminated string
• stack.orange
  • Simple demonstration of calling functions and saving values to the stack
• print.orange
  • Example usage of write syscall for printing a string
• sections.orange
  • Semantics for defining different sections
• linker example
  • Showcases using multiple files to implement a program
  • The main file calls the strLen function in the second file
• greet.orange
  • A simple program that greets the user
  • Makes use of the strio part of the "standard library"

Todo

• Better, more modular parsing of assembly
• Stack management
• Proper error management
• Object files with symbol table, relocation table
• System calls (for console output)
• Dynamic memory allocation via syscalls
• Simple language + compiler