sysdeps/unix/sysv/linux/clock.c

   1 /* Copyright (C) 1991, 1992, 1996 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <sys/times.h>
  20 #include <time.h>
  21 #include <unistd.h>
  22
  23 /* Return the time used by the program so far (user time + system time).  */
  24 clock_t
  25 clock (void)
  26 {
  27   struct tms buf;
  28   long clk_tck = __sysconf (_SC_CLK_TCK);
  29
  30   if (__times (&buf) < 0)
  31     return (clock_t) -1;
  32
  33   return
  34     (clk_tck <= CLOCKS_PER_SEC)
  35     ? ((unsigned long) buf.tms_utime + buf.tms_stime) * (CLOCKS_PER_SEC
  36                                                          / clk_tck)
  37     : ((unsigned long) buf.tms_utime + buf.tms_stime) / (clk_tck
  38                                                          / CLOCKS_PER_SEC);
  39 }