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// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use alloc::{GlobalAlloc, Layout, System};
use sys::c;
use sys_common::alloc::{MIN_ALIGN, realloc_fallback};
#[repr(C)]
struct Header(*mut u8);
unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
&mut *(ptr as *mut Header).offset(-1)
}
unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
let aligned = ptr.add(align - (ptr as usize & (align - 1)));
*get_header(aligned) = Header(ptr);
aligned
}
#[inline]
unsafe fn allocate_with_flags(layout: Layout, flags: c::DWORD) -> *mut u8 {
if layout.align() <= MIN_ALIGN {
return c::HeapAlloc(c::GetProcessHeap(), flags, layout.size()) as *mut u8
}
let size = layout.size() + layout.align();
let ptr = c::HeapAlloc(c::GetProcessHeap(), flags, size);
if ptr.is_null() {
ptr as *mut u8
} else {
align_ptr(ptr as *mut u8, layout.align())
}
}
#[stable(feature = "alloc_system_type", since = "1.28.0")]
unsafe impl GlobalAlloc for System {
#[inline]
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
allocate_with_flags(layout, 0)
}
#[inline]
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
allocate_with_flags(layout, c::HEAP_ZERO_MEMORY)
}
#[inline]
unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
if layout.align() <= MIN_ALIGN {
let err = c::HeapFree(c::GetProcessHeap(), 0, ptr as c::LPVOID);
debug_assert!(err != 0, "Failed to free heap memory: {}",
c::GetLastError());
} else {
let header = get_header(ptr);
let err = c::HeapFree(c::GetProcessHeap(), 0, header.0 as c::LPVOID);
debug_assert!(err != 0, "Failed to free heap memory: {}",
c::GetLastError());
}
}
#[inline]
unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
if layout.align() <= MIN_ALIGN {
c::HeapReAlloc(c::GetProcessHeap(), 0, ptr as c::LPVOID, new_size) as *mut u8
} else {
realloc_fallback(self, ptr, layout, new_size)
}
}
}
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