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#![feature(const_fn)]
#![feature(allocator_api)]
#![no_std]
#[cfg(test)]
#[macro_use]
extern crate std;
#[cfg(feature = "use_spin")]
extern crate spinning_top;
extern crate alloc;
use alloc::alloc::{AllocErr, AllocRef, Layout};
use core::alloc::GlobalAlloc;
use core::mem;
#[cfg(feature = "use_spin")]
use core::ops::Deref;
use core::ptr::NonNull;
use hole::{Hole, HoleList};
#[cfg(feature = "use_spin")]
use spinning_top::Spinlock;
mod hole;
#[cfg(test)]
mod test;
pub struct Heap {
bottom: usize,
size: usize,
holes: HoleList,
}
impl Heap {
pub const fn empty() -> Heap {
Heap {
bottom: 0,
size: 0,
holes: HoleList::empty(),
}
}
pub unsafe fn init(&mut self, heap_bottom: usize, heap_size: usize) {
self.bottom = heap_bottom;
self.size = heap_size;
self.holes = HoleList::new(heap_bottom, heap_size);
}
pub unsafe fn new(heap_bottom: usize, heap_size: usize) -> Heap {
Heap {
bottom: heap_bottom,
size: heap_size,
holes: HoleList::new(heap_bottom, heap_size),
}
}
pub fn allocate_first_fit(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> {
let mut size = layout.size();
if size < HoleList::min_size() {
size = HoleList::min_size();
}
let size = align_up(size, mem::align_of::<Hole>());
let layout = Layout::from_size_align(size, layout.align()).unwrap();
self.holes.allocate_first_fit(layout)
}
pub unsafe fn deallocate(&mut self, ptr: NonNull<u8>, layout: Layout) {
let mut size = layout.size();
if size < HoleList::min_size() {
size = HoleList::min_size();
}
let size = align_up(size, mem::align_of::<Hole>());
let layout = Layout::from_size_align(size, layout.align()).unwrap();
self.holes.deallocate(ptr, layout);
}
pub fn bottom(&self) -> usize {
self.bottom
}
pub fn size(&self) -> usize {
self.size
}
pub fn top(&self) -> usize {
self.bottom + self.size
}
pub unsafe fn extend(&mut self, by: usize) {
let top = self.top();
let layout = Layout::from_size_align(by, 1).unwrap();
self.holes
.deallocate(NonNull::new_unchecked(top as *mut u8), layout);
self.size += by;
}
}
unsafe impl AllocRef for Heap {
unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> {
self.allocate_first_fit(layout)
}
unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) {
self.deallocate(ptr, layout)
}
}
#[cfg(feature = "use_spin")]
pub struct LockedHeap(Spinlock<Heap>);
#[cfg(feature = "use_spin")]
impl LockedHeap {
pub const fn empty() -> LockedHeap {
LockedHeap(Spinlock::new(Heap::empty()))
}
pub unsafe fn new(heap_bottom: usize, heap_size: usize) -> LockedHeap {
LockedHeap(Spinlock::new(Heap {
bottom: heap_bottom,
size: heap_size,
holes: HoleList::new(heap_bottom, heap_size),
}))
}
}
#[cfg(feature = "use_spin")]
impl Deref for LockedHeap {
type Target = Spinlock<Heap>;
fn deref(&self) -> &Spinlock<Heap> {
&self.0
}
}
#[cfg(feature = "use_spin")]
unsafe impl GlobalAlloc for LockedHeap {
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
self.0
.lock()
.allocate_first_fit(layout)
.ok()
.map_or(0 as *mut u8, |allocation| allocation.as_ptr())
}
unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
self.0
.lock()
.deallocate(NonNull::new_unchecked(ptr), layout)
}
}
pub fn align_down(addr: usize, align: usize) -> usize {
if align.is_power_of_two() {
addr & !(align - 1)
} else if align == 0 {
addr
} else {
panic!("`align` must be a power of 2");
}
}
pub fn align_up(addr: usize, align: usize) -> usize {
align_down(addr + align - 1, align)
}