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use crate::alloc::{GlobalAlloc, Layout, System};
static mut DLMALLOC: dlmalloc::Dlmalloc = dlmalloc::Dlmalloc::new();
#[stable(feature = "alloc_system_type", since = "1.28.0")]
unsafe impl GlobalAlloc for System {
#[inline]
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
// SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access.
// Calling malloc() is safe because preconditions on this function match the trait method preconditions.
let _lock = lock::lock();
unsafe { DLMALLOC.malloc(layout.size(), layout.align()) }
}
#[inline]
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
// SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access.
// Calling calloc() is safe because preconditions on this function match the trait method preconditions.
let _lock = lock::lock();
unsafe { DLMALLOC.calloc(layout.size(), layout.align()) }
}
#[inline]
unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
// SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access.
// Calling free() is safe because preconditions on this function match the trait method preconditions.
let _lock = lock::lock();
unsafe { DLMALLOC.free(ptr, layout.size(), layout.align()) }
}
#[inline]
unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
// SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access.
// Calling realloc() is safe because preconditions on this function match the trait method preconditions.
let _lock = lock::lock();
unsafe { DLMALLOC.realloc(ptr, layout.size(), layout.align(), new_size) }
}
}
mod lock {
use crate::sync::atomic::{AtomicI32, Ordering::SeqCst};
static LOCKED: AtomicI32 = AtomicI32::new(0);
pub struct DropLock;
pub fn lock() -> DropLock {
loop {
if LOCKED.swap(1, SeqCst) == 0 {
return DropLock;
}
crate::os::xous::ffi::do_yield();
}
}
impl Drop for DropLock {
fn drop(&mut self) {
let r = LOCKED.swap(0, SeqCst);
debug_assert_eq!(r, 1);
}
}
}
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