use crate::memory::Memory;
use crate::stack::Stack;
use std::io::{Read, Write};
use wain_ast::ValType;
pub enum ImportInvalidError {
NotFound,
SignatureMismatch {
expected_params: &'static [ValType],
expected_ret: Option<ValType>,
},
}
pub enum ImportInvokeError {
Fatal { message: String },
}
pub trait Importer {
fn validate(
&self,
name: &str,
params: &[ValType],
ret: Option<ValType>,
) -> Option<ImportInvalidError>;
fn call(
&mut self,
name: &str,
stack: &mut Stack,
memory: &mut Memory,
) -> Result<(), ImportInvokeError>;
}
pub fn check_func_signature(
actual_params: &[ValType],
actual_ret: Option<ValType>,
expected_params: &'static [ValType],
expected_ret: Option<ValType>,
) -> Option<ImportInvalidError> {
if actual_params.eq(expected_params) && actual_ret == expected_ret {
return None;
}
Some(ImportInvalidError::SignatureMismatch {
expected_params,
expected_ret,
})
}
pub struct DefaultImporter<R: Read, W: Write> {
stdout: W,
stdin: R,
}
impl<R: Read, W: Write> Drop for DefaultImporter<R, W> {
fn drop(&mut self) {
let _ = self.stdout.flush();
}
}
impl<R: Read, W: Write> DefaultImporter<R, W> {
pub fn with_stdio(stdin: R, stdout: W) -> Self {
Self { stdin, stdout }
}
fn putchar(&mut self, stack: &mut Stack) {
let v: i32 = stack.pop();
let b = v as u8;
let ret = match self.stdout.write(&[b]) {
Ok(_) => b as i32,
Err(_) => -1, };
stack.push(ret);
}
fn getchar(&mut self, stack: &mut Stack) {
let mut buf = [0u8];
let v = match self.stdin.read_exact(&mut buf) {
Ok(()) => buf[0] as i32,
Err(_) => -1, };
stack.push(v);
}
fn memcpy(&mut self, stack: &mut Stack, memory: &mut Memory) -> Result<(), ImportInvokeError> {
let size = stack.pop::<i32>() as usize;
let src_start = stack.pop::<i32>() as usize;
let dest_i32: i32 = stack.pop();
let dest_start = dest_i32 as usize;
let src_end = src_start + size;
let dest_end = dest_start + size;
let (dest, src) = if dest_end <= src_start {
let (dest, src) = memory.data_mut().split_at_mut(src_start);
(&mut dest[dest_start..dest_end], &mut src[..size])
} else if src_end <= dest_start {
let (src, dest) = memory.data_mut().split_at_mut(dest_start);
(&mut dest[..size], &mut src[src_start..src_end])
} else {
return Err(ImportInvokeError::Fatal {
message: format!(
"range overwrap on memcpy: src={}..{} and dest={}..{}",
src_start, src_end, dest_start, dest_end
),
});
};
dest.copy_from_slice(&src);
stack.push(dest_i32);
Ok(())
}
}
impl<R: Read, W: Write> Importer for DefaultImporter<R, W> {
fn validate(
&self,
name: &str,
params: &[ValType],
ret: Option<ValType>,
) -> Option<ImportInvalidError> {
use ValType::*;
match name {
"putchar" => check_func_signature(params, ret, &[I32], Some(I32)),
"getchar" => check_func_signature(params, ret, &[], Some(I32)),
"memcpy" => check_func_signature(params, ret, &[I32, I32, I32], Some(I32)),
_ => Some(ImportInvalidError::NotFound),
}
}
fn call(
&mut self,
name: &str,
stack: &mut Stack,
memory: &mut Memory,
) -> Result<(), ImportInvokeError> {
match name {
"putchar" => {
self.putchar(stack);
Ok(())
}
"getchar" => {
self.getchar(stack);
Ok(())
}
"memcpy" => self.memcpy(stack, memory),
_ => unreachable!("fatal: invalid import function '{}'", name),
}
}
}