106 lines
3.1 KiB
Rust
106 lines
3.1 KiB
Rust
extern crate wabt;
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extern crate wasmi;
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use wasmi::{
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Error, Externals, FuncInstance, FuncRef, ImportsBuilder, ModuleImportResolver, ModuleInstance,
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RuntimeArgs, RuntimeValue, Signature, Trap, ValueType,
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};
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pub const KILL: usize = 0;
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pub const ADD_FUNC_INDEX: usize = 1;
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struct HostFunctions;
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impl HostFunctions {
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fn check_signature(&self, index: usize, signature: &Signature) -> bool {
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let (params, ret_ty): (&[ValueType], Option<ValueType>) = match index {
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ADD_FUNC_INDEX => (&[ValueType::I32, ValueType::I32], Some(ValueType::I32)),
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_ => return false,
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};
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signature.params() == params && signature.return_type() == ret_ty
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}
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}
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impl Externals for HostFunctions {
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fn invoke_index(
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&mut self,
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index: usize,
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args: RuntimeArgs,
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) -> Result<Option<RuntimeValue>, Trap> {
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match index {
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ADD_FUNC_INDEX => {
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println!("you pe");
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let a: u32 = args.nth_checked(0)?;
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let b: u32 = args.nth_checked(1)?;
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let result = a + b;
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Ok(Some(RuntimeValue::I32(result as i32)))
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}
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_ => panic!("Unimplemented function at {}", index),
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}
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}
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}
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impl ModuleImportResolver for HostFunctions {
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fn resolve_func(&self, field_name: &str, signature: &Signature) -> Result<FuncRef, Error> {
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let index = match field_name {
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"add" => ADD_FUNC_INDEX,
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_ => {
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return Err(Error::Instantiation(format!(
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"Export {} not found",
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field_name
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)))
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}
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};
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if !self.check_signature(index, signature) {
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return Err(Error::Instantiation(format!(
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"Export {} has a bad signature",
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field_name
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)));
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}
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Ok(FuncInstance::alloc_host(
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Signature::new(&[ValueType::I32, ValueType::I32][..], Some(ValueType::I32)),
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index,
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))
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}
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}
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fn main() {
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// Parse WAT (WebAssembly Text format) into wasm bytecode.
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let wasm_binary = wabt::wat2wasm(include_str!("test.wat"));
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let wasm_binary = match wasm_binary {
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Ok(abc) => abc,
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Err(abc) => {
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println!("{}", abc);
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return;
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}
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};
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// .expect("failed to parse wat");
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// Load wasm binary and prepare it for instantiation.
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let module = wasmi::Module::from_buffer(&wasm_binary).expect("failed to load wasm");
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// Instantiate a module with empty imports and
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// assert that there is no `start` function.
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let instance = ModuleInstance::new(&module, &ImportsBuilder::default())
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.expect("failed to instantiate wasm module")
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.assert_no_start();
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// Finally, invoke the exported function "test" with no parameters
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// and empty external function executor.
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let result: i32 = instance
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.invoke_export("main", &[], &mut HostFunctions)
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// .with_resolver(&mut HostFunctions)
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.expect("failed to execute export")
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.unwrap()
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.try_into()
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.unwrap();
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println!(
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"{:?}",
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result // .unwrap()
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);
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}
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