summaryrefslogtreecommitdiff
path: root/libc/misc/time/clock.c
diff options
context:
space:
mode:
Diffstat (limited to 'libc/misc/time/clock.c')
-rw-r--r--libc/misc/time/clock.c45
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);
+}