| use crate::alloc::{GlobalAlloc, Layout, System}; |
| use crate::sys::c; |
| use crate::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) |
| } |
| } |
| } |