Files
wasmtime/wasmtime-api/examples/multi.rs
2019-10-23 14:09:27 -05:00

90 lines
2.5 KiB
Rust

//! Translation of multi example
extern crate alloc;
use alloc::rc::Rc;
use core::cell::Ref;
use failure::{bail, format_err, Error};
use std::fs::read;
use wasmtime_api::*;
struct Callback;
impl Callable for Callback {
fn call(&self, args: &[Val], results: &mut [Val]) -> Result<(), HostRef<Trap>> {
println!("Calling back...");
println!("> {} {}", args[0].i32(), args[1].i64());
results[0] = Val::I64(args[1].i64() + 1);
results[1] = Val::I32(args[0].i32() + 1);
Ok(())
}
}
fn main() -> Result<(), Error> {
// Initialize.
println!("Initializing...");
let engine = HostRef::new(Engine::new(Config::default()));
let store = HostRef::new(Store::new(engine));
// Load binary.
println!("Loading binary...");
let binary = read("examples/multi.wasm")?;
// Compile.
println!("Compiling module...");
let module = HostRef::new(
Module::new(store.clone(), &binary)
.map_err(|_| format_err!("> Error compiling module!"))?,
);
// Create external print functions.
println!("Creating callback...");
let callback_type = FuncType::new(
Box::new([ValType::I32, ValType::I64]),
Box::new([ValType::I64, ValType::I32]),
);
let callback_func = HostRef::new(Func::new(store.clone(), callback_type, Rc::new(Callback)));
// Instantiate.
println!("Instantiating module...");
let imports = vec![callback_func.into()];
let instance = HostRef::new(
Instance::new(store.clone(), module, imports.as_slice())
.map_err(|_| format_err!("> Error instantiating module!"))?,
);
// Extract export.
println!("Extracting export...");
let exports = Ref::map(instance.borrow(), |instance| instance.exports());
if exports.len() == 0 {
bail!("> Error accessing exports!");
}
let run_func = exports[0]
.func()
.ok_or_else(|| format_err!("> Error accessing exports!"))?;
// Call.
println!("Calling export...");
let args = vec![Val::I32(1), Val::I64(3)];
let results = run_func.borrow().call(&args);
if let Err(_) = results {
bail!("> Error calling function!");
}
let results = results.unwrap();
println!("Printing result...");
println!("> {} {}", results[0].i64(), results[1].i32());
debug_assert!(results[0].i64() == 4);
debug_assert!(results[1].i32() == 2);
// Shut down.
println!("Shutting down...");
drop(store);
// All done.
println!("Done.");
Ok(())
}