Virtual Machine (xrun)

This document describes a lightweight virtual machine designed to execute WebAssembly (WASM) files. Inspired by tools like Wasmer, this VM enables developers to run WASM binaries, invoke specific functions, and pass arguments directly from the command line.

Key Features

  1. Command-Line Interface: The VM accepts WASM files as input and allows invoking specific functions with optional arguments.
  2. Function Invocation: Supports invoking a default main function or any user-specified function within the WASM file.
  3. Input Flexibility: Accepts command-line arguments to be passed to the WASM module.
  4. Bytecode Parsing: Reads and interprets the binary content of the provided WASM file.
  5. Compact and Modular Design: Inspired by Wasmer's philosophy, focusing on simplicity and extensibility.

Argument Handling

  • Help (-h, --help): Displays usage instructions.
  • Invoke Specific Function: Command format: xrun <file.wasm> --invoke function_name [args...].
  • Default Function: If no function is specified, the VM invokes main in the WASM file.

Similarity to Wasmer

  • Shared Goals:

    • Execute WASM files efficiently.
    • Allow invocation of exported functions with arguments.
    • Provide a flexible, CLI-based interface for developers.

  • Key Differences:

    • This VM is more lightweight and tailored to custom workflows.
    • It emphasizes modularity and simplicity, with a minimal dependency footprint.

Usage Examples

  1. Invoke Default main:

    xrun my_program.wasm

  2. Invoke Specific Function:

    xrun my_program.wasm --invoke myFunction arg1 arg2

  3. Show Help:

    xrun -h

Conclusion

This virtual machine bridges the gap between WebAssembly execution and custom command-line workflows. By focusing on modularity and performance, it serves as a lightweight alternative to Wasmer for executing and interacting with WASM modules.