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use crate::Pages;
use loupe::MemoryUsage;
#[cfg(feature = "enable-rkyv")]
use rkyv::{Archive, Deserialize as RkyvDeserialize, Serialize as RkyvSerialize};
#[cfg(feature = "enable-serde")]
use serde::{Deserialize, Serialize};
/// Implementation styles for WebAssembly linear memory.
#[derive(Debug, Clone, PartialEq, Eq, Hash, MemoryUsage)]
#[cfg_attr(
feature = "enable-rkyv",
derive(RkyvSerialize, RkyvDeserialize, Archive)
)]
#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
pub enum MemoryStyle {
/// The actual memory can be resized and moved.
Dynamic {
/// Our chosen offset-guard size.
///
/// It represents the size in bytes of extra guard pages after the end
/// to optimize loads and stores with constant offsets.
offset_guard_size: u64,
},
/// Address space is allocated up front.
Static {
/// The number of mapped and unmapped pages.
bound: Pages,
/// Our chosen offset-guard size.
///
/// It represents the size in bytes of extra guard pages after the end
/// to optimize loads and stores with constant offsets.
offset_guard_size: u64,
},
}
impl MemoryStyle {
/// Returns the offset-guard size
pub fn offset_guard_size(&self) -> u64 {
match self {
Self::Dynamic { offset_guard_size } => *offset_guard_size,
Self::Static {
offset_guard_size, ..
} => *offset_guard_size,
}
}
}