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use crate::globals::Globals;
use crate::trap::{Result, Trap, TrapReason};
use crate::value::LittleEndian;
use std::any;
use std::mem::size_of;
use wain_ast as ast;
const PAGE_SIZE: usize = 65536;
const MAX_MEMORY_BYTES: usize = u32::MAX as usize;
pub struct Memory {
max: Option<u32>,
data: Vec<u8>,
}
impl Memory {
pub fn allocate(memories: &[ast::Memory]) -> Result<Self> {
assert!(memories.len() <= 1);
if let Some(memory) = memories.get(0) {
if let Some(i) = &memory.import {
Err(Trap::unknown_import(i, "memory", memory.start))
} else {
let (min, max) = match &memory.ty.limit {
ast::Limits::Range(min, max) => (*min, Some(*max)),
ast::Limits::From(min) => (*min, None),
};
let data = if min == 0 {
vec![]
} else {
let len = (min as usize) * PAGE_SIZE;
vec![0; len]
};
Ok(Self { max, data })
}
} else {
Ok(Self {
max: Some(0),
data: vec![],
})
}
}
pub fn new_data(&mut self, segment: &ast::DataSegment, globals: &Globals) -> Result<()> {
let offset = match &segment.offset[segment.offset.len() - 1].kind {
ast::InsnKind::GlobalGet(idx) => globals.get(*idx),
ast::InsnKind::I32Const(i) => *i,
_ => unreachable!("unexpected instruction for element offset"),
};
let offset = offset as usize;
let data = &segment.data;
let end_addr = offset + data.len();
if let Some(max) = self.max {
let max = max as usize;
if end_addr > max * PAGE_SIZE {
return Err(Trap::new(
TrapReason::OutOfLimit {
max,
idx: end_addr,
kind: "data element",
},
segment.start,
));
}
}
if self.data.len() < end_addr {
return Err(Trap::new(
TrapReason::DataSegmentOutOfBuffer {
segment_end: end_addr,
buffer_size: self.data.len(),
},
segment.start,
));
}
#[allow(clippy::manual_memcpy)]
{
for i in 0..data.len() {
self.data[offset + i] = data[i];
}
}
Ok(())
}
pub fn size(&self) -> u32 {
(self.data.len() / PAGE_SIZE) as u32
}
pub fn grow(&mut self, num_pages: u32) -> i32 {
let prev = self.size();
let next = prev + num_pages;
if let Some(max) = self.max {
if next > max {
return -1;
}
}
let next_len = (next as usize) * PAGE_SIZE;
if next_len > MAX_MEMORY_BYTES {
return -1;
}
self.data.resize(next_len, 0);
prev as i32
}
fn check_addr<V: LittleEndian>(
&self,
addr: usize,
at: usize,
operation: &'static str,
) -> Result<()> {
if addr.saturating_add(size_of::<V>()) > self.data.len() {
Err(Trap::new(
TrapReason::LoadMemoryOutOfRange {
max: self.data.len(),
addr,
operation,
ty: any::type_name::<V>(),
},
at,
))
} else {
Ok(())
}
}
pub fn load<V: LittleEndian>(&self, addr: usize, at: usize) -> Result<V> {
self.check_addr::<V>(addr, at, "load")?;
Ok(LittleEndian::read(&self.data, addr))
}
pub fn store<V: LittleEndian>(&mut self, addr: usize, v: V, at: usize) -> Result<()> {
self.check_addr::<V>(addr, at, "store")?;
LittleEndian::write(&mut self.data, addr, v);
Ok(())
}
pub fn data(&self) -> &'_ [u8] {
&self.data
}
pub fn data_mut(&mut self) -> &mut [u8] {
&mut self.data
}
}