AssemblyScript bindings

Currently this binding library is compatible with wasmer and we are studying on a compatibility with wasmtime. With this helper are able to read, write and use the allocation in your webassembly modules compiled from AssemblyScript.

Read

We provide two helpers, StringPtr and BufferPtr. The string correspond to a string in AssemblyScript and the BufferPtr to ArrayBuffer. If you want to read the return of a native function. It's really easy.

use as_ffi_bindings::{Read, StringPtr};
let instance = Instance::new(&module, &import_object)?;
let memory = instance.exports.get_memory("memory").expect("get memory");
// Instanciation of your wasmer things

let get_string = instance
    .exports
    .get_native_function::<(), StringPtr>("getString")?;
// Get native function in your module

let str_ptr: StringPtr = get_string.call()?;
// Get directly a string pointer

let string: String = str_ptr.read(memory)?;

Note: If you choose to use as_ffi_bindings::Env you also have access to the memory when you declare your native function with env (using wasmer) so the memory of the instance is allays disponible.

let str_ptr: BufferPtr = get_buffer.call()?;
// Get directly a buffer pointer

let buffer: Vec<u8> = buffer_ptr.read(memory)?;

Allocation/Writing

use as_ffi_bindings::{Write};

The Write traits allow you to free (indevelopment), write and allocate StringPtr and BufferPtr. This will allow you to send a value to your AssemblyScript module from rust!!

let input: Vec<u8> = vec![0x03, 0x02, 0x00, 0x01];
// instanciate a vector
let buffer_ptr = BufferPtr::alloc(&input, &env)?;
// Allocate a new buffer on the defined environment
sort_buffer.call(buffer_ptr.offset() as i32)?;
// Sort your buffer in webassembly

Everything remains accessible in the rust side. You can modfy your variable in the rust side with the .write() method and obviously in the webassembly module. So it's better to consider this as an unsafe action, pay attention 🥲.

Env instanciation

You need to init your environment to allocate and write, it's because you need to use exported function as __new, __pin, accordingly to the beautifull AssemblyScript memory documentation 📚. This is automatically initialised when wasmer call a function in the ImportObject with an environment (examples comming soon).

But when wasmer isn't behind you, you haveto use your own hands! Look:

let mut env = Env::default();
env.init(&instance)?;

Not hard, right?

More usage example

There is more subtil things to initialise, as the abort function in the ImportObject. Full examples for using features are in the test_features.rs file and we tried to use simple examples.

License