1 /* * Copyright (c) 2018 Apple Inc. All rights reserved. 2 * 3 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ 4 * 5 * This file contains Original Code and/or Modifications of Original Code 6 * as defined in and that are subject to the Apple Public Source License 7 * Version 2.0 (the 'License'). You may not use this file except in 8 * compliance with the License. The rights granted to you under the License 9 * may not be used to create, or enable the creation or redistribution of, 10 * unlawful or unlicensed copies of an Apple operating system, or to 11 * circumvent, violate, or enable the circumvention or violation of, any 12 * terms of an Apple operating system software license agreement. 13 * 14 * Please obtain a copy of the License at 15 * http://www.opensource.apple.com/apsl/ and read it before using this file. 16 * 17 * The Original Code and all software distributed under the License are 18 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 19 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 20 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 21 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 22 * Please see the License for the specific language governing rights and 23 * limitations under the License. 24 * 25 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ 26 */ 27 28 #ifndef _OS_PTRTOOLS_H 29 #define _OS_PTRTOOLS_H 30 31 /* dereference unaligned pointer 'p' */ 32 #define os_unaligned_deref(p) ((__os_unaligned_type(p))(p))->val 33 34 /* ensure the compiler emits at most one access to 'val' */ 35 #define os_access_once(val) (*((volatile __typeof__((val)) *)&(val))) 36 37 #define __os_unaligned_type(p) struct { __typeof__(*(p)) val; } __attribute__((packed)) * 38 39 #endif /* _OS_PTRTOOLS_H */ 40