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use crate::{Memory, WASM_PAGE_SIZE};
use std::cell::RefCell;
use std::ops::Deref;
use std::rc::Rc;
const MAX_PAGES: u64 = i64::MAX as u64 / WASM_PAGE_SIZE;
pub type VectorMemory = Rc<RefCell<Vec<u8>>>;
impl Memory for RefCell<Vec<u8>> {
fn size(&self) -> u64 {
self.borrow().len() as u64 / WASM_PAGE_SIZE
}
fn grow(&self, pages: u64) -> i64 {
let size = self.size();
match size.checked_add(pages) {
Some(n) => {
if n > MAX_PAGES {
return -1;
}
self.borrow_mut()
.resize((n * WASM_PAGE_SIZE as u64) as usize, 0);
size as i64
}
None => -1,
}
}
fn read(&self, offset: u64, dst: &mut [u8]) {
let n = offset
.checked_add(dst.len() as u64)
.expect("read: out of bounds");
if n as usize > self.borrow().len() {
panic!("read: out of bounds");
}
dst.copy_from_slice(&self.borrow()[offset as usize..n as usize]);
}
fn write(&self, offset: u64, src: &[u8]) {
let n = offset
.checked_add(src.len() as u64)
.expect("write: out of bounds");
if n as usize > self.borrow().len() {
panic!("write: out of bounds");
}
self.borrow_mut()[offset as usize..n as usize].copy_from_slice(src);
}
}
impl<M: Memory> Memory for Rc<M> {
fn size(&self) -> u64 {
self.deref().size()
}
fn grow(&self, pages: u64) -> i64 {
self.deref().grow(pages)
}
fn read(&self, offset: u64, dst: &mut [u8]) {
self.deref().read(offset, dst)
}
fn write(&self, offset: u64, src: &[u8]) {
self.deref().write(offset, src)
}
}