1/*
2 * Copyright (c) 2008-2013 Apple Inc. All rights reserved.
3 *
4 * @APPLE_APACHE_LICENSE_HEADER_START@
5 *
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 *     http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 *
18 * @APPLE_APACHE_LICENSE_HEADER_END@
19 */
20
21/*
22 * IMPORTANT: This header file describes INTERNAL interfaces to libdispatch
23 * which are subject to change in future releases of Mac OS X. Any applications
24 * relying on these interfaces WILL break.
25 */
26
27#ifndef __DISPATCH_SHIMS_TIME__
28#define __DISPATCH_SHIMS_TIME__
29
30#ifndef __DISPATCH_INDIRECT__
31#error "Please #include <dispatch/dispatch.h> instead of this file directly."
32#endif
33
34#if TARGET_OS_WIN32
35static inline unsigned int
36sleep(unsigned int seconds)
37{
38	Sleep(seconds * 1000); // milliseconds
39	return 0;
40}
41#endif
42
43uint64_t _dispatch_get_nanoseconds(void);
44
45#if defined(__i386__) || defined(__x86_64__) || !HAVE_MACH_ABSOLUTE_TIME
46// x86 currently implements mach time in nanoseconds
47// this is NOT likely to change
48DISPATCH_ALWAYS_INLINE
49static inline uint64_t
50_dispatch_time_mach2nano(uint64_t machtime)
51{
52	return machtime;
53}
54
55DISPATCH_ALWAYS_INLINE
56static inline uint64_t
57_dispatch_time_nano2mach(uint64_t nsec)
58{
59	return nsec;
60}
61#else
62typedef struct _dispatch_host_time_data_s {
63	dispatch_once_t pred;
64	long double frac;
65	bool ratio_1_to_1;
66} _dispatch_host_time_data_s;
67extern _dispatch_host_time_data_s _dispatch_host_time_data;
68void _dispatch_get_host_time_init(void *context);
69
70static inline uint64_t
71_dispatch_time_mach2nano(uint64_t machtime)
72{
73	_dispatch_host_time_data_s *const data = &_dispatch_host_time_data;
74	dispatch_once_f(&data->pred, NULL, _dispatch_get_host_time_init);
75
76	if (!machtime || slowpath(data->ratio_1_to_1)) {
77		return machtime;
78	}
79	if (machtime >= INT64_MAX) {
80		return INT64_MAX;
81	}
82	long double big_tmp = ((long double)machtime * data->frac) + .5;
83	if (slowpath(big_tmp >= INT64_MAX)) {
84		return INT64_MAX;
85	}
86	return (uint64_t)big_tmp;
87}
88
89static inline uint64_t
90_dispatch_time_nano2mach(uint64_t nsec)
91{
92	_dispatch_host_time_data_s *const data = &_dispatch_host_time_data;
93	dispatch_once_f(&data->pred, NULL, _dispatch_get_host_time_init);
94
95	if (!nsec || slowpath(data->ratio_1_to_1)) {
96		return nsec;
97	}
98	if (nsec >= INT64_MAX) {
99		return INT64_MAX;
100	}
101	long double big_tmp = ((long double)nsec / data->frac) + .5;
102	if (slowpath(big_tmp >= INT64_MAX)) {
103		return INT64_MAX;
104	}
105	return (uint64_t)big_tmp;
106}
107#endif
108
109static inline uint64_t
110_dispatch_absolute_time(void)
111{
112#if HAVE_MACH_ABSOLUTE_TIME
113	return mach_absolute_time();
114#elif TARGET_OS_WIN32
115	LARGE_INTEGER now;
116	return QueryPerformanceCounter(&now) ? now.QuadPart : 0;
117#else
118	struct timespec ts;
119	int ret;
120
121#if HAVE_DECL_CLOCK_UPTIME
122	ret = clock_gettime(CLOCK_UPTIME, &ts);
123#elif HAVE_DECL_CLOCK_MONOTONIC
124	ret = clock_gettime(CLOCK_MONOTONIC, &ts);
125#else
126#error "clock_gettime: no supported absolute time clock"
127#endif
128	(void)dispatch_assume_zero(ret);
129
130	/* XXXRW: Some kind of overflow detection needed? */
131	return (ts.tv_sec * NSEC_PER_SEC + ts.tv_nsec);
132#endif // HAVE_MACH_ABSOLUTE_TIME
133}
134
135
136#endif // __DISPATCH_SHIMS_TIME__
137