path: root/examples/wasm-rust.rs

use color_eyre::eyre::Result;
use tinywasm::{Extern, FuncContext, Imports, MemoryStringExt, Module, Store};

fn main() -> Result<()> {
    let args = std::env::args().collect::<Vec<_>>();
    if args.len() < 2 {
        println!("Usage: cargo run --example wasm-rust <rust_example>");
        println!("Available examples:");
        println!("  hello");
        println!("  printi32");
        println!("  fibonacci - calculate fibonacci(30)");
        println!("  tinywasm - run printi32 inside of tinywasm inside of itself");
        return Ok(());
    }

    match args[1].as_str() {
        "hello" => hello()?,
        "printi32" => printi32()?,
        "fibonacci" => fibonacci()?,
        "tinywasm" => tinywasm()?,
        _ => {}
    }

    Ok(())
}

fn tinywasm() -> Result<()> {
    const TINYWASM: &[u8] = include_bytes!("./rust/out/tinywasm.wasm");
    let module = Module::parse_bytes(&TINYWASM)?;
    let mut store = Store::default();

    let mut imports = Imports::new();
    imports.define(
        "env",
        "printi32",
        Extern::typed_func(|_: FuncContext<'_>, x: i32| {
            println!("{}", x);
            Ok(())
        }),
    )?;
    let instance = module.instantiate(&mut store, Some(imports))?;

    let hello = instance.exported_func::<(), ()>(&mut store, "hello")?;
    hello.call(&mut store, ())?;

    Ok(())
}

fn hello() -> Result<()> {
    const HELLO_WASM: &[u8] = include_bytes!("./rust/out/hello.wasm");
    let module = Module::parse_bytes(&HELLO_WASM)?;
    let mut store = Store::default();

    let mut imports = Imports::new();
    imports.define(
        "env",
        "print_utf8",
        Extern::typed_func(|mut ctx: FuncContext<'_>, args: (i64, i32)| {
            let mem = ctx.exported_memory("memory")?;
            let ptr = args.0 as usize;
            let len = args.1 as usize;
            let string = mem.load_string(ptr, len)?;
            println!("{}", string);
            Ok(())
        }),
    )?;

    let instance = module.instantiate(&mut store, Some(imports))?;
    let arg_ptr = instance.exported_func::<(), i32>(&mut store, "arg_ptr")?.call(&mut store, ())?;
    let arg = b"world";

    instance.exported_memory_mut(&mut store, "memory")?.store(arg_ptr as usize, arg.len(), arg)?;
    let hello = instance.exported_func::<i32, ()>(&mut store, "hello")?;
    hello.call(&mut store, arg.len() as i32)?;

    Ok(())
}

fn printi32() -> Result<()> {
    const HELLO_WASM: &[u8] = include_bytes!("./rust/out/print.wasm");
    let module = Module::parse_bytes(&HELLO_WASM)?;
    let mut store = Store::default();

    let mut imports = Imports::new();
    imports.define(
        "env",
        "printi32",
        Extern::typed_func(|_: FuncContext<'_>, x: i32| {
            println!("{}", x);
            Ok(())
        }),
    )?;

    let instance = module.instantiate(&mut store, Some(imports))?;
    let add_and_print = instance.exported_func::<(i32, i32), ()>(&mut store, "add_and_print")?;
    add_and_print.call(&mut store, (1, 2))?;

    Ok(())
}

fn fibonacci() -> Result<()> {
    const FIBONACCI_WASM: &[u8] = include_bytes!("./rust/out/fibonacci.wasm");
    let module = Module::parse_bytes(&FIBONACCI_WASM)?;
    let mut store = Store::default();

    let instance = module.instantiate(&mut store, None)?;
    let fibonacci = instance.exported_func::<i32, i32>(&mut store, "fibonacci")?;
    let n = 30;
    let result = fibonacci.call(&mut store, n)?;
    println!("fibonacci({}) = {}", n, result);

    Ok(())
}