lib/xtime.h

   1 /* xtime -- extended-resolution integer timestamps
   2
   3    Copyright (C) 2005-2006, 2009-2017 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 <http://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Paul Eggert.  */
  19
  20 #ifndef XTIME_H_
  21 #define XTIME_H_ 1
  22
  23 #ifndef _GL_INLINE_HEADER_BEGIN
  24  #error "Please include config.h first."
  25 #endif
  26 _GL_INLINE_HEADER_BEGIN
  27 #ifndef XTIME_INLINE
  28 # define XTIME_INLINE _GL_INLINE
  29 #endif
  30
  31 /* xtime_t is a signed type used for timestamps.  It is an integer
  32    type that is a count of nanoseconds -- except for obsolescent hosts
  33    without sufficiently-wide integers, where it is a count of
  34    seconds.  */
  35 #if HAVE_LONG_LONG_INT
  36 typedef long long int xtime_t;
  37 # define XTIME_PRECISION 1000000000
  38 #else
  39 # include <limits.h>
  40 typedef long int xtime_t;
  41 # if LONG_MAX >> 31 >> 31 == 0
  42 #  define XTIME_PRECISION 1
  43 # else
  44 #  define XTIME_PRECISION 1000000000
  45 # endif
  46 #endif
  47
  48 #ifdef  __cplusplus
  49 extern "C" {
  50 #endif
  51
  52 /* Return an extended time value that contains S seconds and NS
  53    nanoseconds, without any overflow checking.  */
  54 XTIME_INLINE xtime_t
  55 xtime_make (xtime_t s, long int ns)
  56 {
  57   if (XTIME_PRECISION == 1)
  58     return s;
  59   else
  60     return XTIME_PRECISION * s + ns;
  61 }
  62
  63 /* Return the number of seconds in T, which must be nonnegative.  */
  64 XTIME_INLINE xtime_t
  65 xtime_nonnegative_sec (xtime_t t)
  66 {
  67   return t / XTIME_PRECISION;
  68 }
  69
  70 /* Return the number of seconds in T.  */
  71 XTIME_INLINE xtime_t
  72 xtime_sec (xtime_t t)
  73 {
  74   return (XTIME_PRECISION == 1
  75           ? t
  76           : t < 0
  77           ? (t + XTIME_PRECISION - 1) / XTIME_PRECISION - 1
  78           : xtime_nonnegative_sec (t));
  79 }
  80
  81 /* Return the number of nanoseconds in T, which must be nonnegative.  */
  82 XTIME_INLINE long int
  83 xtime_nonnegative_nsec (xtime_t t)
  84 {
  85   return t % XTIME_PRECISION;
  86 }
  87
  88 /* Return the number of nanoseconds in T.  */
  89 XTIME_INLINE long int
  90 xtime_nsec (xtime_t t)
  91 {
  92   long int ns = t % XTIME_PRECISION;
  93   if (ns < 0)
  94     ns += XTIME_PRECISION;
  95   return ns;
  96 }
  97
  98 #ifdef  __cplusplus
  99 }
 100 #endif
 101
 102 #endif