Provides utilities for loading and running WASM modules

Built on top of the Wasmer runtime.

Setup

Start by installing the tools needed to build the Wasmer runtime:

• Install the Rust SDK.

• On Windows, to get link.exe, install the Visual Studio build tools with the "Desktop development with C++"-option selected.

Basic Usage

As a simple example, we'll try to call a simple C function from Dart using package:wasm. For a more detailed example that uses WASI, check out the example directory.

1. First create new Dart app folder: dart create wasmtest

2. Add a dependency to package wasm in pubspec.yaml and run dart pub get

3. Next run dart run wasm:setup to build the Wasmer runtime. This will take a few minutes.

4. Then add a new file square.cc with the following contents:

   extern "C" int square(int n) { return n * n; }
   

5. We can compile this C++ code to WASM using a recent version of the clang compiler:

   clang --target=wasm32 -nostdlib "-Wl,--export-all" "-Wl,--no-entry" -o square.wasm square.cc
   

6. Replace the contents of your Dart program (bin/wasmtest.dart) with:

   import 'dart:io';
   import 'package:wasm/wasm.dart';
      
   void main() {
     final data = File('square.wasm').readAsBytesSync();
     final mod = WasmModule(data);
     print(mod.describe());
     final inst = mod.builder().build();
     final square = inst.lookupFunction('square');
     print(square(12));
   }
   

7. Run the Dart program: dart run. This should print:

   export memory: memory
   export function: int32 square(int32)
      
   144