399295a708
* Tidy up the `hello` example for `wasmtime` * Remove the `*.wat` and `*.wasm` files and instead just inline the `*.wat` into the example. * Touch up comments so they're not just a repeat of the `println!` below. * Move `*.wat` for `memory` example inline No need to handle auxiliary files with the ability to parse it inline! * Move `multi.wasm` inline into `multi.rs` example * Move `*.wasm` for gcd example inline * Move `*.wat` inline with `import_calling_export` test * Remove checked in `lightbeam/test.wasm` Instead move the `*.wat` into the source and parse it into wasm there. * Run rustfmt
73 lines
1.6 KiB
Rust
73 lines
1.6 KiB
Rust
//! Example of instantiating of the WebAssembly module and
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//! invoking its exported function.
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use anyhow::{format_err, Result};
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use wasmtime_api::*;
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const WAT: &str = r#"
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(module
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(func $gcd (param i32 i32) (result i32)
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(local i32)
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block ;; label = @1
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block ;; label = @2
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local.get 0
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br_if 0 (;@2;)
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local.get 1
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local.set 2
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br 1 (;@1;)
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end
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loop ;; label = @2
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local.get 1
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local.get 0
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local.tee 2
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i32.rem_u
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local.set 0
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local.get 2
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local.set 1
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local.get 0
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br_if 0 (;@2;)
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end
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end
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local.get 2
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)
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(export "gcd" (func $gcd))
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)
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"#;
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fn main() -> Result<()> {
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let wasm = wat::parse_str(WAT)?;
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// Instantiate engine and store.
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let engine = HostRef::new(Engine::default());
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let store = HostRef::new(Store::new(&engine));
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// Load a module.
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let module = HostRef::new(Module::new(&store, &wasm)?);
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// Find index of the `gcd` export.
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let gcd_index = module
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.borrow()
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.exports()
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.iter()
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.enumerate()
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.find(|(_, export)| export.name().to_string() == "gcd")
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.unwrap()
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.0;
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// Instantiate the module.
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let instance = HostRef::new(Instance::new(&store, &module, &[])?);
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// Invoke `gcd` export
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let gcd = instance.borrow().exports()[gcd_index]
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.func()
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.expect("gcd")
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.clone();
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let result = gcd
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.borrow()
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.call(&[Val::from(6i32), Val::from(27i32)])
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.map_err(|e| format_err!("call error: {:?}", e))?;
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println!("{:?}", result);
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Ok(())
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}
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