Add asynchronous external JS calls to your WASM that behave as sync WASM functions
npm install async-wasm
Currently there is no way to do async calls from wasm (all external calls are sync). This means it's tricky to call out from WASM to do I/O in Javascript.
This module makes was support that, by using a Worker thread from Node.js to run the WASM and resolve the async calls in the main worker, while the thread is blocking.
NOTE: You might have to run your program with node --experimental-worker app.js since
this is using the worker_threads core module.
const AsyncWasm = require('async-wasm')
const fs = require('fs')
// Create a new async WASM worker based on a WASM buffer.
// In this example, hello.wasm has one external function hello_world,
// that calls out to a function called fetch in the hypermachine namespace.
const aw = new AsyncWasm(fs.readFileSync('hello.wasm'), {
hypermachine: {
fetch (ptr, cb) {
console.log('fetch is called with argument:', ptr)
// read(ptr, len, cb) reads from the wasm memory
aw.read(ptr, 10, function (_, buf) {
console.log('read', buf)
// write(ptr, buf, cb) writes to the wasm memory
aw.write(ptr, Buffer.from('lolol'), function () {
console.log('wrote data')
aw.read(ptr, 10, function (_, buf) {
console.log('read now', buf)
// Call the callback with a numeric return value when done
// If you call it with an error, -1 is returned in wasm.
cb(null, 10)
})
})
})
}
}
})
// Invoke external methods on the WASM using the `.call(name, ...args, cb)` method.
aw.call('hello_world', function (err, val) {
console.log('done', err, val)
aw.destroy()
})See the example folder for a full example that contains the WAT/WASM code as well.
MIT