libsyscall/wrappers/mach_approximate_time.c

   1 /*
   2  * Copyright (c) 2008 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 #include <sys/types.h>
  24 #include <machine/cpu_capabilities.h>
  25
  26 extern uint64_t mach_absolute_time(void);
  27
  28 #if defined(__arm64__) || defined(__x86_64__)
  29
  30 uint64_t
  31 mach_approximate_time(void)
  32 {
  33         uint8_t supported = *((uint8_t *)_COMM_PAGE_APPROX_TIME_SUPPORTED);
  34         if (supported) {
  35                 return *((uint64_t *)_COMM_PAGE_APPROX_TIME);
  36         }
  37         return mach_absolute_time();
  38 }
  39
  40 #endif