lib/xtime.h

   1 /* xtime -- extended-resolution integer timestamps
   2
   3    Copyright (C) 2005-2006, 2009-2024 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation, either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Paul Eggert.  */
  19
  20 #ifndef XTIME_H_
  21 #define XTIME_H_ 1
  22
  23 /* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE.  */
  24 #if !_GL_CONFIG_H_INCLUDED
  25  #error "Please include config.h first."
  26 #endif
  27
  28 _GL_INLINE_HEADER_BEGIN
  29 #ifndef XTIME_INLINE
  30 # define XTIME_INLINE _GL_INLINE
  31 #endif
  32
  33 /* xtime_t is a signed type used for timestamps.  It is an integer
  34    type that is a count of nanoseconds.  */
  35 typedef long long int xtime_t;
  36 #define XTIME_PRECISION 1000000000
  37
  38 #ifdef  __cplusplus
  39 extern "C" {
  40 #endif
  41
  42 /* Return an extended time value that contains S seconds and NS
  43    nanoseconds.  S and NS should be nonnegative; otherwise, integer
  44    overflow can occur even if the result is in range.  */
  45 XTIME_INLINE xtime_t
  46 xtime_make (xtime_t s, long int ns)
  47 {
  48   return XTIME_PRECISION * s + ns;
  49 }
  50
  51 /* The following functions split an extended time value:
  52    T = XTIME_PRECISION * xtime_sec (T) + xtime_nsec (T)
  53    with  0 <= xtime_nsec (T) < XTIME_PRECISION.  */
  54
  55 /* Return the number of seconds in T, which must be nonnegative.  */
  56 XTIME_INLINE xtime_t
  57 xtime_nonnegative_sec (xtime_t t)
  58 {
  59   return t / XTIME_PRECISION;
  60 }
  61
  62 /* Return the number of seconds in T.  */
  63 XTIME_INLINE xtime_t
  64 xtime_sec (xtime_t t)
  65 {
  66   return (t + (t < 0)) / XTIME_PRECISION - (t < 0);
  67 }
  68
  69 /* Return the number of nanoseconds in T, which must be nonnegative.  */
  70 XTIME_INLINE long int
  71 xtime_nonnegative_nsec (xtime_t t)
  72 {
  73   return t % XTIME_PRECISION;
  74 }
  75
  76 /* Return the number of nanoseconds in T.  */
  77 XTIME_INLINE long int
  78 xtime_nsec (xtime_t t)
  79 {
  80   long int ns = t % XTIME_PRECISION;
  81   if (ns < 0)
  82     ns += XTIME_PRECISION;
  83   return ns;
  84 }
  85
  86 #ifdef  __cplusplus
  87 }
  88 #endif
  89
  90 _GL_INLINE_HEADER_END
  91
  92 #endif