glibc/sysdeps/unix/sysv/linux/clock.c

40 lines
1.4 KiB
C

/* Return the time used by the program so far (user time + system time).
Copyright (C) 1991-2015 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>
clock_t
clock (void)
{
struct timespec ts;
_Static_assert (CLOCKS_PER_SEC == 1000000,
"CLOCKS_PER_SEC should be 1000000");
/* clock_gettime shouldn't fail here since CLOCK_PROCESS_CPUTIME_ID is
supported since 2.6.12. Check the return value anyway in case the kernel
barfs on us for some reason. */
if (__glibc_unlikely (__clock_gettime (CLOCK_PROCESS_CPUTIME_ID, &ts) != 0))
return (clock_t) -1;
return (ts.tv_sec * CLOCKS_PER_SEC
+ ts.tv_nsec / (1000000000 / CLOCKS_PER_SEC));
}