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use super::*;
/// An encoder for the memory section.
///
/// # Example
///
/// ```
/// use wasm_encoder::{Module, MemorySection, MemoryType};
///
/// let mut memories = MemorySection::new();
/// memories.memory(MemoryType {
/// minimum: 1,
/// maximum: None,
/// memory64: false,
/// });
///
/// let mut module = Module::new();
/// module.section(&memories);
///
/// let wasm_bytes = module.finish();
/// ```
#[derive(Clone, Default, Debug)]
pub struct MemorySection {
bytes: Vec<u8>,
num_added: u32,
}
impl MemorySection {
/// Create a new memory section encoder.
pub fn new() -> Self {
Self::default()
}
/// How many memories have been defined inside this section so far?
pub fn len(&self) -> u32 {
self.num_added
}
/// Determines if the section is empty.
pub fn is_empty(&self) -> bool {
self.num_added == 0
}
/// Define a memory.
pub fn memory(&mut self, memory_type: MemoryType) -> &mut Self {
memory_type.encode(&mut self.bytes);
self.num_added += 1;
self
}
}
impl Section for MemorySection {
fn id(&self) -> u8 {
SectionId::Memory.into()
}
fn encode<S>(&self, sink: &mut S)
where
S: Extend<u8>,
{
let num_added = encoders::u32(self.num_added);
let n = num_added.len();
sink.extend(
encoders::u32(u32::try_from(n + self.bytes.len()).unwrap())
.chain(num_added)
.chain(self.bytes.iter().copied()),
);
}
}
/// A memory's type.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct MemoryType {
/// Minimum size, in pages, of this memory
pub minimum: u64,
/// Maximum size, in pages, of this memory
pub maximum: Option<u64>,
/// Whether or not this is a 64-bit memory.
pub memory64: bool,
}
impl MemoryType {
pub(crate) fn encode(&self, bytes: &mut Vec<u8>) {
let mut flags = 0;
if self.maximum.is_some() {
flags |= 0b001;
}
if self.memory64 {
flags |= 0b100;
}
bytes.push(flags);
bytes.extend(encoders::u64(self.minimum));
if let Some(max) = self.maximum {
bytes.extend(encoders::u64(max));
}
}
}