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// FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
#![allow(static_mut_refs)]
use crate::alloc::{GlobalAlloc, Layout, System};
use crate::ptr;
use crate::sync::atomic::{AtomicBool, Ordering};
// Symbols for heap section boundaries defined in the target's linkerscript
unsafe extern "C" {
static mut __heap_start: u8;
static mut __heap_end: u8;
}
static mut DLMALLOC: dlmalloc::Dlmalloc<Vexos> = dlmalloc::Dlmalloc::new_with_allocator(Vexos);
struct Vexos;
unsafe impl dlmalloc::Allocator for Vexos {
/// Allocs system resources
fn alloc(&self, _size: usize) -> (*mut u8, usize, u32) {
static INIT: AtomicBool = AtomicBool::new(false);
if !INIT.swap(true, Ordering::Relaxed) {
// This target has no growable heap, as user memory has a fixed
// size/location and VEXos does not manage allocation for us.
unsafe {
(
(&raw mut __heap_start).cast::<u8>(),
(&raw const __heap_end).offset_from_unsigned(&raw const __heap_start),
0,
)
}
} else {
(ptr::null_mut(), 0, 0)
}
}
fn remap(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize, _can_move: bool) -> *mut u8 {
ptr::null_mut()
}
fn free_part(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize) -> bool {
false
}
fn free(&self, _ptr: *mut u8, _size: usize) -> bool {
return false;
}
fn can_release_part(&self, _flags: u32) -> bool {
false
}
fn allocates_zeros(&self) -> bool {
false
}
fn page_size(&self) -> usize {
0x1000
}
}
#[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 we are a single-threaded target, which
// guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used.
// Calling malloc() is safe because preconditions on this function match the trait method preconditions.
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 we are a single-threaded target, which
// guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used.
// Calling calloc() is safe because preconditions on this function match the trait method preconditions.
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 we are a single-threaded target, which
// guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used.
// Calling free() is safe because preconditions on this function match the trait method preconditions.
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 we are a single-threaded target, which
// guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used.
// Calling realloc() is safe because preconditions on this function match the trait method preconditions.
unsafe { DLMALLOC.realloc(ptr, layout.size(), layout.align(), new_size) }
}
}
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