# WASM Usage

WebAssembly 2.0 is supported except for exceptions and threads. The supported WASM feature set is the same as the features supported by `wasm2c` 1.0.34 when used with default options (no cmd line switches passed). See WASM features supported by `wasm2c` in the following [table](https://github.com/WebAssembly/wabt/blob/1.0.34/README.md#supported-proposals).

From WASI only standard input and standard output are supported.

Use `/valida-toolchain/bin/compile-wasm.sh` to compile a `.wasm` program into a Valida executable:

```
/valida-toolchain/bin/compile-wasm.sh file.wasm -o output_path
```

`file.wasm` must export an entrypoint called `_start` that doesn't take any arguments and returns no value.

The `compile-wasm.sh` compilation pipeline involves an intermediate step that compiles WASM to C with `wasm2c`. Then C is compiled to Valida executable with Valida toolchain.

It's assumed that Valida toolchain is installed and is located at the default installation location: `/valida-toolchain`

It's assumed that `wasm2c` and `wat2wasm` in version 1.0.34 are in PATH. On Ubuntu 24.04 these can be installed with a command: `apt install wabt`.

See WASM examples bundled in the release package or in the toolchain Docker image at `/valida-toolchain/examples/wasm`.