An experimental microkernel OS
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use crate::{print, println};
use alloc::vec::Vec;
use wasmi::{
Error as InterpreterError, Externals, FuncInstance, FuncRef, ImportsBuilder,
ModuleImportResolver, ModuleInstance, RuntimeArgs, RuntimeValue, Signature, Trap, ValueType,
};
#[cfg(test)]
use crate::{serial_print, serial_println};
mod hack;
async fn load_wasm_module() -> wasmi::Module {
let bytes = include_bytes!("../../data/h.wasm");
let b: Vec<u8> = bytes.iter().cloned().collect();
println!(" loaded wasm into a Vec");
wasmi::Module::from_buffer(&b).unwrap()
}
pub async fn run() {
let module = load_wasm_module().await;
let mut imports = ImportsBuilder::new();
imports.push_resolver("h", &H);
let instance = ModuleInstance::new(&module, &imports)
.expect("failed to load wasm module")
.assert_no_start();
println!(" invoking export");
let _ = instance.invoke_export("h", &[], &mut H);
}
#[test_case]
fn test_wasm() {
serial_print!("running h example... ");
let _ = run();
serial_println!("[ok]");
}
struct H;
const H_FUNC: usize = 0;
impl Externals for H {
fn invoke_index(
&mut self,
index: usize,
args: RuntimeArgs,
) -> Result<Option<RuntimeValue>, Trap> {
use core::char::from_u32;
match index {
H_FUNC => {
let ch_t: i32 = args.nth(0);
let ch = from_u32(ch_t as u32);
print!("{}", ch.unwrap());
Ok(None)
}
_ => panic!("unknown function called"),
}
}
}
impl ModuleImportResolver for H {
fn resolve_func(
&self,
field_name: &str,
_signature: &Signature,
) -> Result<FuncRef, InterpreterError> {
let func_ref = match field_name {
"h" => FuncInstance::alloc_host(Signature::new(&[ValueType::I32][..], None), H_FUNC),
_ => panic!("unknwon function asked for"),
};
Ok(func_ref)
}
}