diff options
Diffstat (limited to 'libc/misc/time/clock.c')
-rw-r--r-- | libc/misc/time/clock.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/libc/misc/time/clock.c b/libc/misc/time/clock.c new file mode 100644 index 000000000..4d1a17869 --- /dev/null +++ b/libc/misc/time/clock.c @@ -0,0 +1,45 @@ +/* Copyright (C) 1991, 1992, 1996, 1999 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <sys/times.h> +#include <time.h> +#include <unistd.h> + +/* Return the time used by the program so far (user time + system time). */ +clock_t +clock (void) +{ + struct tms buf; + long clk_tck = sysconf (_SC_CLK_TCK); + + /* We don't check for errors here. The only error the kernel + returns is EFAULT if the value cannot be written to the struct we + pass a pointer to. Otherwise the kernel returns an `unsigned + long' value which is the number of jiffies since system start. + But this number can be negative (when read as `long') when the + system is up for some time. Ignoring errors should therefore + have no negative impacts but solve the problem. */ + times (&buf); + + return + (clk_tck <= CLOCKS_PER_SEC) + ? ((unsigned long) buf.tms_utime + buf.tms_stime) * (CLOCKS_PER_SEC + / clk_tck) + : ((unsigned long) buf.tms_utime + buf.tms_stime) / (clk_tck + / CLOCKS_PER_SEC); +} |