src/shims/time.h

   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
  35 static inline unsigned int
  36 sleep(unsigned int seconds)
  37 {
  38         Sleep(seconds * 1000); // milliseconds
  39         return 0;
  40 }
  41 #endif
  42
  43 uint64_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
  48 DISPATCH_ALWAYS_INLINE
  49 static inline uint64_t
  50 _dispatch_time_mach2nano(uint64_t machtime)
  51 {
  52         return machtime;
  53 }
  54
  55 DISPATCH_ALWAYS_INLINE
  56 static inline uint64_t
  57 _dispatch_time_nano2mach(uint64_t nsec)
  58 {
  59         return nsec;
  60 }
  61 #else
  62 typedef 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;
  67 extern _dispatch_host_time_data_s _dispatch_host_time_data;
  68 void _dispatch_get_host_time_init(void *context);
  69
  70 static 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
  89 static 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
 109 static 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 static inline uint64_t
 136 _dispatch_approximate_time(void)
 137 {
 138         return _dispatch_absolute_time();
 139 }
 140
 141 #endif // __DISPATCH_SHIMS_TIME__