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glibc  2.9
clock.c
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00001 /* Copyright (C) 1991, 1997, 1998, 1999 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <sys/resource.h>
00020 #include <sys/time.h>
00021 #include <time.h>
00022 
00023 #ifdef __GNUC__
00024 __inline
00025 #endif
00026 static clock_t
00027 timeval_to_clock_t (const struct timeval *tv)
00028 {
00029   return (clock_t) ((tv->tv_sec * CLOCKS_PER_SEC) +
00030                   (tv->tv_usec * CLOCKS_PER_SEC / 1000000));
00031 }
00032 
00033 /* Return the time used by the program so far (user time + system time).  */
00034 clock_t
00035 clock (void)
00036 {
00037   struct rusage usage;
00038 
00039   if (__getrusage (RUSAGE_SELF, &usage) < 0)
00040     return (clock_t) -1;
00041 
00042   return (timeval_to_clock_t (&usage.ru_stime) +
00043          timeval_to_clock_t (&usage.ru_utime));
00044 }