8e1b44b29c
* Make more code work with no_std. no_std support is still incomplete, but this patch takes care of the bulk of the straightforward parts.
75 lines
2.0 KiB
Rust
75 lines
2.0 KiB
Rust
//! Translation of hello example
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extern crate alloc;
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use alloc::rc::Rc;
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use core::cell::Ref;
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use failure::{bail, format_err, Error};
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use std::fs::read;
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use wasmtime_api::*;
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struct HelloCallback;
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impl Callable for HelloCallback {
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fn call(&self, _params: &[Val], _results: &mut [Val]) -> Result<(), HostRef<Trap>> {
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println!("Calling back...");
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println!("> Hello World!");
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Ok(())
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}
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}
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fn main() -> Result<(), Error> {
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// Initialize.
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println!("Initializing...");
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let engine = HostRef::new(Engine::new(Config::default()));
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let store = HostRef::new(Store::new(engine));
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// Load binary.
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println!("Loading binary...");
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let binary = read("examples/hello.wasm")?;
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// Compile.
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println!("Compiling module...");
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let module = HostRef::new(
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Module::new(store.clone(), &binary)
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.map_err(|_| format_err!("> Error compiling module!"))?,
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);
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// Create external print functions.
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println!("Creating callback...");
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let hello_type = FuncType::new(Box::new([]), Box::new([]));
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let hello_func = HostRef::new(Func::new(store.clone(), hello_type, Rc::new(HelloCallback)));
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// Instantiate.
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println!("Instantiating module...");
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let imports = vec![hello_func.into()];
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let instance = HostRef::new(
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Instance::new(store.clone(), module, imports.as_slice())
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.map_err(|_| format_err!("> Error instantiating module!"))?,
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);
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// Extract export.
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println!("Extracting export...");
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let exports = Ref::map(instance.borrow(), |instance| instance.exports());
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if exports.len() == 0 {
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bail!("> Error accessing exports!");
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}
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let run_func = exports[0]
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.func()
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.ok_or_else(|| format_err!("> Error accessing exports!"))?;
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// Call.
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println!("Calling export...");
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if let Err(_) = run_func.borrow().call(&[]) {
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bail!("> Error calling function!");
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}
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// Shut down.
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println!("Shutting down...");
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drop(store);
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// All done.
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println!("Done.");
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Ok(())
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}
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