lib/timespec.h

   1 /* timespec -- System time interface
   2
   3    Copyright (C) 2000, 2002, 2004-2005, 2007, 2009-2024 Free Software
   4    Foundation, Inc.
   5
   6    This file is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU Lesser General Public License as
   8    published by the Free Software Foundation, either version 3 of the
   9    License, or (at your option) any later version.
  10
  11    This file is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #if ! defined TIMESPEC_H
  20 #define TIMESPEC_H
  21
  22 /* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE, _GL_ATTRIBUTE_CONST,
  23    _GL_ATTRIBUTE_PURE, _GL_CMP.  */
  24 #if !_GL_CONFIG_H_INCLUDED
  25  #error "Please include config.h first."
  26 #endif
  27
  28 #include <time.h>
  29
  30 _GL_INLINE_HEADER_BEGIN
  31 #ifndef _GL_TIMESPEC_INLINE
  32 # define _GL_TIMESPEC_INLINE _GL_INLINE
  33 #endif
  34
  35 #ifdef __cplusplus
  36 extern "C" {
  37 #endif
  38
  39 #include "arg-nonnull.h"
  40
  41 /* Inverse resolution of timespec timestamps (in units per second),
  42    and log base 10 of the inverse resolution.  */
  43
  44 enum { TIMESPEC_HZ = 1000000000 };
  45 enum { LOG10_TIMESPEC_HZ = 9 };
  46
  47 /* Obsolescent names for backward compatibility.
  48    They are misnomers, because TIMESPEC_RESOLUTION is not a resolution.  */
  49
  50 enum { TIMESPEC_RESOLUTION = TIMESPEC_HZ };
  51 enum { LOG10_TIMESPEC_RESOLUTION = LOG10_TIMESPEC_HZ };
  52
  53 /* Return a timespec with seconds S and nanoseconds NS.  */
  54
  55 _GL_TIMESPEC_INLINE struct timespec
  56 make_timespec (time_t s, long int ns)
  57 {
  58   return (struct timespec) { .tv_sec = s, .tv_nsec = ns };
  59 }
  60
  61 /* Return negative, zero, positive if A < B, A == B, A > B, respectively.  */
  62
  63 _GL_TIMESPEC_INLINE int _GL_ATTRIBUTE_PURE
  64 timespec_cmp (struct timespec a, struct timespec b)
  65 {
  66   return 2 * _GL_CMP (a.tv_sec, b.tv_sec) + _GL_CMP (a.tv_nsec, b.tv_nsec);
  67 }
  68
  69 /* Return -1, 0, 1, depending on the sign of A.  A.tv_nsec must be
  70    nonnegative.  */
  71 _GL_TIMESPEC_INLINE int _GL_ATTRIBUTE_PURE
  72 timespec_sign (struct timespec a)
  73 {
  74   return _GL_CMP (a.tv_sec, 0) + (!a.tv_sec & !!a.tv_nsec);
  75 }
  76
  77 struct timespec timespec_add (struct timespec, struct timespec)
  78   _GL_ATTRIBUTE_CONST;
  79 struct timespec timespec_sub (struct timespec, struct timespec)
  80   _GL_ATTRIBUTE_CONST;
  81 struct timespec dtotimespec (double)
  82   _GL_ATTRIBUTE_CONST;
  83
  84 /* Return an approximation to A, of type 'double'.  */
  85 _GL_TIMESPEC_INLINE double
  86 timespectod (struct timespec a)
  87 {
  88   return a.tv_sec + a.tv_nsec / 1e9;
  89 }
  90
  91 long int gettime_res (void);
  92 struct timespec current_timespec (void);
  93 void gettime (struct timespec *) _GL_ARG_NONNULL ((1));
  94 int settime (struct timespec const *) _GL_ARG_NONNULL ((1));
  95
  96 #ifdef __cplusplus
  97 }
  98 #endif
  99
 100 _GL_INLINE_HEADER_END
 101
 102 #endif