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# Wasmi - WebAssembly (Wasm) Interpreter
<p align="center">
<img src="./resources/wasmi-logo.png" width="100" height="100">
</p>
Wasmi is an efficient and lightweight WebAssembly interpreter with a focus on constrained and embedded systems.
Version `0.31.0` has been [audited by SRLabs].
[Wasmtime]: https://github.com/bytecodealliance/wasmtime
[audited by SRLabs]: ./resources/security-audit-2023-12-20.pdf
## Announcement: Transfer of Ownership
As of 2024-02-01, the original owner and maintainer of the Wasmi project, Parity Technologies, has officially transferred ownership of the project to me, Robin Freyler. Read more about this transfer [here](NEWS.md#announcement-transfer-of-ownership).
## Distinct Features
The following list states some of the distinct features of Wasmi.
- Simple, correct and deterministic execution of WebAssembly.
- Low-overhead and cross-platform WebAssembly runtime for embedded environments.
- JIT bomb resisting translation.
- Loosely mirrors the [Wasmtime API](https://docs.rs/wasmtime/).
- 100% WebAssembly spec testsuite compliance.
- Built-in support for fuel metering.
## WebAssembly Proposals
The new Wasmi engine supports a variety of WebAssembly proposals and will support even more of them in the future.
| [`mutable-global`] | ✅ | Since version `0.14.0`. |
| [`saturating-float-to-int`] | ✅ | Since version `0.14.0`. |
| [`sign-extension`] | ✅ | Since version `0.14.0`. |
| [`multi-value`] | ✅ | Since version `0.14.0`. |
| [`bulk-memory`] | ✅ | Since version `0.24.0`. [(#628)] |
| [`reference-types`] | ✅ | Since version `0.24.0`. [(#635)] |
| [`simd`] | ❌ | Unlikely to be supported. |
| [`tail-calls`] | ✅ | Since version `0.28.0`. [(#683)] |
| [`extended-const`] | ✅ | Since version `0.29.0`. [(#707)] |
| [`function-references`] | 📅 | Planned but not yet implemented. [(#774)] |
| [`gc`] | 📅 | Planned but not yet implemented. [(#775)] |
| [`multi-memory`] | 📅 | Planned but not yet implemented. [(#776)] |
| [`threads`] | 📅 | Planned but not yet implemented. [(#777)] |
| [`relaxed-simd`] | ❌ | Unlikely to be supported since `simd` is unlikely to be supported. |
| [`component-model`] | 📅 | Planned but not yet implemented. [(#897)] |
| | |
| [WASI] | 👨🔬 | Experimental support via the [`wasmi_wasi` crate] or the Wasmi CLI application. |
[`mutable-global`]: https://github.com/WebAssembly/mutable-global
[`saturating-float-to-int`]: https://github.com/WebAssembly/nontrapping-float-to-int-conversions
[`sign-extension`]: https://github.com/WebAssembly/sign-extension-ops
[`multi-value`]: https://github.com/WebAssembly/multi-value
[`reference-types`]: https://github.com/WebAssembly/reference-types
[`bulk-memory`]: https://github.com/WebAssembly/bulk-memory-operations
[`simd` ]: https://github.com/webassembly/simd
[`tail-calls`]: https://github.com/WebAssembly/tail-call
[`extended-const`]: https://github.com/WebAssembly/extended-const
[`function-references`]: https://github.com/WebAssembly/function-references
[`gc`]: https://github.com/WebAssembly/gc
[`multi-memory`]: https://github.com/WebAssembly/multi-memory
[`threads`]: https://github.com/WebAssembly/threads
[`relaxed-simd`]: https://github.com/WebAssembly/relaxed-simd
[`component-model`]: https://github.com/WebAssembly/component-model
[WASI]: https://github.com/WebAssembly/WASI
[`wasmi_wasi` crate]: ./crates/wasi
[(#363)]: https://github.com/wasmi-labs/wasmi/issues/363
[(#364)]: https://github.com/wasmi-labs/wasmi/issues/364
[(#496)]: https://github.com/wasmi-labs/wasmi/issues/496
[(#628)]: https://github.com/wasmi-labs/wasmi/pull/628
[(#635)]: https://github.com/wasmi-labs/wasmi/pull/635
[(#638)]: https://github.com/wasmi-labs/wasmi/pull/638
[(#683)]: https://github.com/wasmi-labs/wasmi/pull/683
[(#707)]: https://github.com/wasmi-labs/wasmi/pull/707
[(#774)]: https://github.com/wasmi-labs/wasmi/pull/774
[(#775)]: https://github.com/wasmi-labs/wasmi/pull/775
[(#776)]: https://github.com/wasmi-labs/wasmi/pull/776
[(#777)]: https://github.com/wasmi-labs/wasmi/pull/777
[(#897)]: https://github.com/wasmi-labs/wasmi/pull/897
## Usage
### As CLI Application
Install the newest Wasmi CLI version:
```console
cargo install wasmi_cli
```
Run `wasm32-unknown-unknown` or `wasm32-wasi` Wasm binaries:
```console
wasmi_cli <WASM_FILE> --invoke <FUNC_NAME> [<FUNC_ARGS>]*
```
### As Rust Library
Refer to the [Wasmi crate docs](https://docs.rs/wasmi) to learn how to use the [Wasmi crate](https://crates.io/crates/wasmi) as library.
## Development
### Build & Test
Clone the Wasmi repository and build using `cargo`:
```console
git clone https://github.com/wasmi-labs/wasmi.git --recursive
cd wasmi
cargo build
cargo test
```
### Benchmarks
In order to benchmark Wasmi use the following command:
```console
cargo bench
```
Use `translate`, `instantiate`, `execute` or `overhead` filters to only run benchmarks that test performance of Wasm translation, instantiation, execution or miscellaneous overhead respectively, e.g. `cargo bench execute`.
We maintain a timeline for benchmarks of every commit to `master` that [can be viewed here](https://wasmi-labs.github.io/wasmi/benchmarks/).
## Supported Platforms
Wasmi supports a wide variety of architectures and platforms.
- Fore more details see this [list of supported platforms for Rust](https://doc.rust-lang.org/stable/rustc/platform-support.html).
- **Note:** Wasmi can be used in `no_std` embedded environments, thus not requiring the standard library (`std`).
- Only some platforms are checked in CI and guaranteed to be fully working by the Wasmi maintainers.
## Production Builds
In order to reap the most performance out of Wasmi we highly recommended
to compile the Wasmi crate using the following Cargo `profile`:
```toml
[profile.release]
lto = "fat"
codegen-units = 1
```
When compiling for the WebAssembly target we highly recommend to post-optimize
Wasmi using [Binaryen]'s `wasm-opt` tool since our experiments displayed a
80-100% performance improvements when executed under Wasmtime and also
slightly smaller Wasm binaries.
[Binaryen]: https://github.com/WebAssembly/binaryen
## License
Licensed under either of
* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or <http://www.apache.org/licenses/LICENSE-2.0>)
* MIT license ([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)
at your option.
## Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.