Files
wasmtime/wasmtime-api/src/callable.rs
Yury Delendik f88e92a57c Better Wasmtime API for embedder (#287)
* Migrate wasm-rust-api code to wasmtime.
2019-08-21 00:35:26 -07:00

98 lines
3.1 KiB
Rust

use crate::runtime::Store;
use crate::trap::Trap;
use crate::values::Val;
use core::any::Any;
use std::cell::RefCell;
use std::rc::Rc;
use cranelift_codegen::ir;
use wasmtime_runtime::{VMContext, VMFunctionBody};
pub trait Callable: Any {
fn call(&self, params: &[Val], results: &mut [Val]) -> Result<(), Rc<RefCell<Trap>>>;
}
pub(crate) struct WasmtimeFn {
store: Rc<RefCell<Store>>,
signature: ir::Signature,
body: *const VMFunctionBody,
vmctx: *mut VMContext,
}
impl WasmtimeFn {
pub fn new(
store: Rc<RefCell<Store>>,
signature: ir::Signature,
body: *const VMFunctionBody,
vmctx: *mut VMContext,
) -> WasmtimeFn {
WasmtimeFn {
store,
signature,
body,
vmctx,
}
}
}
impl Callable for WasmtimeFn {
fn call(&self, params: &[Val], results: &mut [Val]) -> Result<(), Rc<RefCell<Trap>>> {
use core::cmp::max;
use core::{mem, ptr};
let mut store = self.store.borrow_mut();
let context = store.context();
let value_size = mem::size_of::<u64>();
let mut values_vec: Vec<u64> = vec![0; max(params.len(), results.len())];
// Store the argument values into `values_vec`.
for (index, arg) in params.iter().enumerate() {
unsafe {
let ptr = values_vec.as_mut_ptr().add(index);
match arg {
Val::I32(x) => ptr::write(ptr as *mut i32, *x),
Val::I64(x) => ptr::write(ptr as *mut i64, *x),
Val::F32(x) => ptr::write(ptr as *mut u32, *x),
Val::F64(x) => ptr::write(ptr as *mut u64, *x),
_ => unimplemented!("WasmtimeFn arg"),
}
}
}
// Get the trampoline to call for this function.
let exec_code_buf = context
.compiler()
.get_published_trampoline(self.body, &self.signature, value_size)
.map_err(|_| Rc::new(RefCell::new(Trap::fake())))?; //was ActionError::Setup)?;
// Call the trampoline.
if let Err(message) = unsafe {
wasmtime_runtime::wasmtime_call_trampoline(
self.vmctx,
exec_code_buf,
values_vec.as_mut_ptr() as *mut u8,
)
} {
return Err(Rc::new(RefCell::new(Trap::new(message))));
}
// Load the return values out of `values_vec`.
for (index, abi_param) in self.signature.returns.iter().enumerate() {
unsafe {
let ptr = values_vec.as_ptr().add(index);
results[index] = match abi_param.value_type {
ir::types::I32 => Val::I32(ptr::read(ptr as *const i32)),
ir::types::I64 => Val::I64(ptr::read(ptr as *const i64)),
ir::types::F32 => Val::F32(ptr::read(ptr as *const u32)),
ir::types::F64 => Val::F64(ptr::read(ptr as *const u64)),
other => panic!("unsupported value type {:?}", other),
}
}
}
Ok(())
}
}