bits/time.h

   1 /* System-dependent timing definitions.  Generic version.
   2    Copyright (C) 1996-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /*
  20  * Never include this file directly; use <time.h> instead.
  21  */
  22
  23 #ifndef _BITS_TIME_H
  24 #define _BITS_TIME_H    1
  25
  26 #include <bits/types.h>
  27
  28 /* ISO/IEC 9899:1999 7.23.1: Components of time
  29    The macro `CLOCKS_PER_SEC' is an expression with type `clock_t' that is
  30    the number per second of the value returned by the `clock' function.  */
  31 /* CAE XSH, Issue 4, Version 2: <time.h>
  32    The value of CLOCKS_PER_SEC is required to be 1 million on all
  33    XSI-conformant systems. */
  34 #define CLOCKS_PER_SEC  ((__clock_t) 1000000)
  35
  36 #if (!defined __STRICT_ANSI__ || defined __USE_POSIX) \
  37    && !defined __USE_XOPEN2K
  38 /* Even though CLOCKS_PER_SEC has such a strange value CLK_TCK
  39    presents the real value for clock ticks per second for the system.  */
  40 extern long int __sysconf (int);
  41 # define CLK_TCK ((__clock_t) __sysconf (2))    /* 2 is _SC_CLK_TCK */
  42 #endif
  43
  44 #ifdef __USE_POSIX199309
  45 /* Identifier for system-wide realtime clock.  */
  46 # define CLOCK_REALTIME                 0
  47 /* Monotonic system-wide clock.  */
  48 # define CLOCK_MONOTONIC                1
  49 /* High-resolution timer from the CPU.  */
  50 # define CLOCK_PROCESS_CPUTIME_ID       2
  51 /* Thread-specific CPU-time clock.  */
  52 # define CLOCK_THREAD_CPUTIME_ID        3
  53 /* Monotonic system-wide clock, not adjusted for frequency scaling.  */
  54 # define CLOCK_MONOTONIC_RAW            4
  55 /* Identifier for system-wide realtime clock, updated only on ticks.  */
  56 # define CLOCK_REALTIME_COARSE          5
  57 /* Monotonic system-wide clock, updated only on ticks.  */
  58 # define CLOCK_MONOTONIC_COARSE         6
  59
  60 /* Flag to indicate time is absolute.  */
  61 # define TIMER_ABSTIME                  1
  62 #endif
  63
  64 #endif  /* bits/time.h */