/* timespec -- System time interface
- Copyright (C) 2000, 2002, 2004-2005, 2007, 2009-2010 Free Software
+ Copyright (C) 2000, 2002, 2004-2005, 2007, 2009-2018 Free Software
Foundation, Inc.
This program is free software: you can redistribute it and/or modify
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
#if ! defined TIMESPEC_H
# define TIMESPEC_H
# include <time.h>
+#ifndef _GL_INLINE_HEADER_BEGIN
+ #error "Please include config.h first."
+#endif
+_GL_INLINE_HEADER_BEGIN
+#ifndef _GL_TIMESPEC_INLINE
+# define _GL_TIMESPEC_INLINE _GL_INLINE
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "verify.h"
+
+/* Resolution of timespec timestamps (in units per second), and log
+ base 10 of the resolution. */
+
+enum { TIMESPEC_RESOLUTION = 1000000000 };
+enum { LOG10_TIMESPEC_RESOLUTION = 9 };
+
+/* Return a timespec with seconds S and nanoseconds NS. */
+
+_GL_TIMESPEC_INLINE struct timespec
+make_timespec (time_t s, long int ns)
+{
+ struct timespec r;
+ r.tv_sec = s;
+ r.tv_nsec = ns;
+ return r;
+}
+
/* Return negative, zero, positive if A < B, A == B, A > B, respectively.
- Assume the nanosecond components are in range, or close to it. */
-static inline int
+
+ For each timestamp T, this code assumes that either:
+
+ * T.tv_nsec is in the range 0..999999999; or
+ * T.tv_sec corresponds to a valid leap second on a host that supports
+ leap seconds, and T.tv_nsec is in the range 1000000000..1999999999; or
+ * T.tv_sec is the minimum time_t value and T.tv_nsec is -1; or
+ T.tv_sec is the maximum time_t value and T.tv_nsec is 2000000000.
+ This allows for special struct timespec values that are less or
+ greater than all possible valid timestamps.
+
+ In all these cases, it is safe to subtract two tv_nsec values and
+ convert the result to integer without worrying about overflow on
+ any platform of interest to the GNU project, since all such
+ platforms have 32-bit int or wider.
+
+ Replacing "a.tv_nsec - b.tv_nsec" with something like
+ "a.tv_nsec < b.tv_nsec ? -1 : a.tv_nsec > b.tv_nsec" would cause
+ this function to work in some cases where the above assumption is
+ violated, but not in all cases (e.g., a.tv_sec==1, a.tv_nsec==-2,
+ b.tv_sec==0, b.tv_nsec==999999999) and is arguably not worth the
+ extra instructions. Using a subtraction has the advantage of
+ detecting some invalid cases on platforms that detect integer
+ overflow. */
+
+_GL_TIMESPEC_INLINE int _GL_ATTRIBUTE_PURE
timespec_cmp (struct timespec a, struct timespec b)
{
- return (a.tv_sec < b.tv_sec ? -1
- : a.tv_sec > b.tv_sec ? 1
- : a.tv_nsec < b.tv_nsec ? -1
- : a.tv_nsec > b.tv_nsec ? 1
- : 0);
+ if (a.tv_sec < b.tv_sec)
+ return -1;
+ if (a.tv_sec > b.tv_sec)
+ return 1;
+
+ /* Pacify gcc -Wstrict-overflow (bleeding-edge circa 2017-10-02). See:
+ http://lists.gnu.org/r/bug-gnulib/2017-10/msg00006.html */
+ assume (-1 <= a.tv_nsec && a.tv_nsec <= 2 * TIMESPEC_RESOLUTION);
+ assume (-1 <= b.tv_nsec && b.tv_nsec <= 2 * TIMESPEC_RESOLUTION);
+
+ return a.tv_nsec - b.tv_nsec;
+}
+
+/* Return -1, 0, 1, depending on the sign of A. A.tv_nsec must be
+ nonnegative. */
+_GL_TIMESPEC_INLINE int _GL_ATTRIBUTE_PURE
+timespec_sign (struct timespec a)
+{
+ return a.tv_sec < 0 ? -1 : a.tv_sec || a.tv_nsec;
+}
+
+struct timespec timespec_add (struct timespec, struct timespec)
+ _GL_ATTRIBUTE_CONST;
+struct timespec timespec_sub (struct timespec, struct timespec)
+ _GL_ATTRIBUTE_CONST;
+struct timespec dtotimespec (double)
+ _GL_ATTRIBUTE_CONST;
+
+/* Return an approximation to A, of type 'double'. */
+_GL_TIMESPEC_INLINE double
+timespectod (struct timespec a)
+{
+ return a.tv_sec + a.tv_nsec / 1e9;
}
void gettime (struct timespec *);
int settime (struct timespec const *);
+#ifdef __cplusplus
+}
+#endif
+
+_GL_INLINE_HEADER_END
+
#endif