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/* Copyright (C) 1991-2013 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#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);
}
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