1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
use super::alloc::alloc::{GlobalAlloc, Layout};
use core::ptr;
type LockedAllocator = super::Locked<Allocator>;
unsafe impl GlobalAlloc for LockedAllocator {
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
let mut inner = self.lock();
let alloc_start = super::align_up(inner.next, layout.align());
let alloc_end = match alloc_start.checked_add(layout.size()) {
Some(end) => end,
None => return ptr::null_mut(),
};
if alloc_end > inner.heap_end {
ptr::null_mut()
} else {
inner.next = alloc_end;
inner.allocations += 1;
alloc_start as *mut u8
}
}
unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
let mut inner = self.lock();
inner.allocations -= 1;
if inner.allocations == 0 {
inner.next = inner.heap_start;
}
}
}
pub(super) struct Allocator {
heap_start: usize,
heap_end: usize,
next: usize,
allocations: usize,
}
impl Allocator {
#[allow(dead_code)]
pub(super) const fn new() -> Self {
Self {
heap_start: 0,
heap_end: 0,
next: 0,
allocations: 0,
}
}
#[allow(dead_code)]
pub(super) unsafe fn init(&mut self, heap_start: usize, heap_size: usize) {
self.heap_start = heap_start;
self.heap_end = heap_start + heap_size;
self.next = heap_start;
}
}