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45 lines
1.7 KiB
C
45 lines
1.7 KiB
C
/* Copyright (C) 1991-2013 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sys/times.h>
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#include <time.h>
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#include <unistd.h>
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/* Return the time used by the program so far (user time + system time). */
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clock_t
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clock (void)
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{
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struct tms buf;
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long clk_tck = __sysconf (_SC_CLK_TCK);
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/* We don't check for errors here. The only error the kernel
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returns is EFAULT if the value cannot be written to the struct we
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pass a pointer to. Otherwise the kernel returns an `unsigned
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long' value which is the number of jiffies since system start.
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But this number can be negative (when read as `long') when the
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system is up for some time. Ignoring errors should therefore
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have no negative impacts but solve the problem. */
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__times (&buf);
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return
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(clk_tck <= CLOCKS_PER_SEC)
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? ((unsigned long) buf.tms_utime + buf.tms_stime) * (CLOCKS_PER_SEC
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/ clk_tck)
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: ((unsigned long) buf.tms_utime + buf.tms_stime) / (clk_tck
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/ CLOCKS_PER_SEC);
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}
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