zig-stack-vm

A reimplementation of a university project in zig. Implements a simple stack-based bytecode virtual machine.

Installation

This project was developed on Zig 0.8. Zig is a fast moving language, newer (and older) versions might not be able to compile it.

git clone https://github.com/pedromsilvapt/zig-stack-vm.git
cd zig-stack-vm
zig build

Optionally one can build the application in release mode to get better execution performance (at the expense of compilation speed).

zig build -Drelease-fast

Usage

The compiled application can be ran directly from the command line, and accepts one file path as an argument.

./zig-out/bin/stackvm ./examples/fib.ir

Aditionally one can also embed the virtual machine in a custom application easily. Just add the package path in your build file and require it like so.

const std = @import("std");
const svm = @import("stack-vm");
const Parser = svm.Parser;
const VirtualMachine = svm.VirtualMachine;

pub fn main () !void {
    var general_purpose_allocator = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = general_purpose_allocator.deinit();
    
    var allocator = &general_purpose_allocator.allocator;

    const source = 
        \\ pushs "Type your name, please.\n"
        \\ writes
        \\ read
        \\ pushs "Hello, "
        \\ writes
        \\ writes
        \\ pushs "!\n"
        \\ writes
        ;

    var parser = try Parser.init(allocator, source);
    defer parser.deinit();

    var bytecode = try parser.parse();

    // Takes ownership of the bytecode and is responsible for freeing it on deinit
    var vm = VirtualMachine.init(allocator, bytecode);
    defer vm.deinit();

    try vm.execute();
}

Python Bindings

This repository provides bindings to work with the StackVM from Python. The file bindings/python/libstackvm.py found in this repository should be copied to your project. Then edit the line there to point to your shared library built with Zig:

lib = cdll.LoadLibrary("libstackvm.dll")

Below is a simple example of how to use the bindings.

from libstackvm import *

with open( "examples/fib.ir", 'r') as f:
        content = f.read()

    parser = Parser.init(content)

    reader = parser.parse()
    
    vm = VirtualMachine.init(reader)

    try:
        vm.execute()

        while vm.stack:
            val = vm.stack.pop()

            print("Stack value", val.value)

        print("-- POINTERS")
        print("-- fp:", vm.registers.frame_pointer)
        print("-- sp:", vm.registers.stack_pointer)
        print("-- cp:", vm.registers.code_pointer)
        print("-- gp:", vm.registers.global_pointer)
    except BaseException as ex:
        print(ex)
        
        vm.deinit()
        reader.destroy()
        parser.deinit()