[apple/xnu.git] / libkern / os / ptrtools.h

/* * Copyright (c) 2018 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#ifndef _OS_PTRTOOLS_H
#define _OS_PTRTOOLS_H

/* dereference unaligned pointer 'p' */
#define os_unaligned_deref(p) ((__os_unaligned_type(p))(p))->val

/* ensure the compiler emits at most one access to 'val' */
#define os_access_once(val) (*((volatile __typeof__((val)) *)&(val)))

#define __os_unaligned_type(p) struct { __typeof__(*(p)) val; } __attribute__((packed)) *

#endif /* _OS_PTRTOOLS_H */
Commit	Line	Data
cb323159	1	/* * Copyright (c) 2018 Apple Inc. All rights reserved.
5ba3f43e A	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@
3e170ce0	26	*/
fe8ab488	27
cb323159 A	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))
fe8ab488	38
cb323159	39	#endif /* _OS_PTRTOOLS_H */