lib/timespec.h

   1 /* timespec -- System time interface
   2
   3    Copyright (C) 2000, 2002, 2004-2005, 2007, 2009-2020 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program 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 General Public License for more details.
  15
  16    You should have received a copy of the GNU 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 #include <time.h>
  23
  24 #ifndef _GL_INLINE_HEADER_BEGIN
  25  #error "Please include config.h first."
  26 #endif
  27 _GL_INLINE_HEADER_BEGIN
  28 #ifndef _GL_TIMESPEC_INLINE
  29 # define _GL_TIMESPEC_INLINE _GL_INLINE
  30 #endif
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36 #include "arg-nonnull.h"
  37
  38 /* Inverse resolution of timespec timestamps (in units per second),
  39    and log base 10 of the inverse resolution.  */
  40
  41 enum { TIMESPEC_HZ = 1000000000 };
  42 enum { LOG10_TIMESPEC_HZ = 9 };
  43
  44 /* Obsolescent names for backward compatibility.
  45    They are misnomers, because TIMESPEC_RESOLUTION is not a resolution.  */
  46
  47 enum { TIMESPEC_RESOLUTION = TIMESPEC_HZ };
  48 enum { LOG10_TIMESPEC_RESOLUTION = LOG10_TIMESPEC_HZ };
  49
  50 /* Return a timespec with seconds S and nanoseconds NS.  */
  51
  52 _GL_TIMESPEC_INLINE struct timespec
  53 make_timespec (time_t s, long int ns)
  54 {
  55   struct timespec r;
  56   r.tv_sec = s;
  57   r.tv_nsec = ns;
  58   return r;
  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 struct timespec current_timespec (void);
  92 void gettime (struct timespec *) _GL_ARG_NONNULL ((1));
  93 int settime (struct timespec const *) _GL_ARG_NONNULL ((1));
  94
  95 #ifdef __cplusplus
  96 }
  97 #endif
  98
  99 _GL_INLINE_HEADER_END
 100
 101 #endif