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1/*
2 * Copyright (c) 2016 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 <mach/mach_time.h>
24
25extern kern_return_t
26mach_timebase_info_trap(mach_timebase_info_t info);
27
28kern_return_t
29mach_timebase_info(mach_timebase_info_t info){
30 static mach_timebase_info_data_t cached_info;
31
32 /*
33 * This is racy, but because it is safe to initialize twice we avoid a
34 * barrier in the fast path by risking double initialization.
35 */
36 if (cached_info.numer == 0 || cached_info.denom == 0){
37 kern_return_t kr = mach_timebase_info_trap(&cached_info);
38 if (kr != KERN_SUCCESS) return kr;
39 }
40
41 info->numer = cached_info.numer;
42 info->denom = cached_info.denom;
43
44 return KERN_SUCCESS;
45}