This is xnu-8019. See this file in:
/*
 * Copyright (c) 2000 Apple Computer, 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@
 */
/*
 * Copyright (c) 1999 Apple Computer, Inc.  All rights reserved.
 *
 * HISTORY
 *
 */

#ifndef _OS_OSBASE_H
#define _OS_OSBASE_H

#include <sys/cdefs.h>

#include <libkern/OSTypes.h>

#include <stdint.h>

__BEGIN_DECLS

#ifdef  KERNEL_PRIVATE

OS_INLINE
uint64_t
__OSAbsoluteTime(
	AbsoluteTime    abstime)
{
	return *(uint64_t *)&abstime;
}

OS_INLINE
uint64_t *
__OSAbsoluteTimePtr(
	AbsoluteTime    *abstime)
{
	return (uint64_t *)abstime;
}

#define AbsoluteTime_to_scalar(x)       (*(uint64_t *)(x))

/* t1 < = > t2 */
#define CMP_ABSOLUTETIME(t1, t2)                                \
	(AbsoluteTime_to_scalar(t1) >                           \
	        AbsoluteTime_to_scalar(t2)? (int)+1 :   \
	 (AbsoluteTime_to_scalar(t1) <                          \
	        AbsoluteTime_to_scalar(t2)? (int)-1 : 0))

/* t1 += t2 */
#define ADD_ABSOLUTETIME(t1, t2)                                \
	(AbsoluteTime_to_scalar(t1) +=                          \
	                        AbsoluteTime_to_scalar(t2))

/* t1 -= t2 */
#define SUB_ABSOLUTETIME(t1, t2)                                \
	(AbsoluteTime_to_scalar(t1) -=                          \
	                        AbsoluteTime_to_scalar(t2))

#define ADD_ABSOLUTETIME_TICKS(t1, ticks)               \
	(AbsoluteTime_to_scalar(t1) +=                          \
	                                        (int32_t)(ticks))

#endif  /* KERNEL_PRIVATE */

__END_DECLS

#endif /* _OS_OSBASE_H */