doc: use ASCII in .texi files where UTF-8 isn't needed

[gnulib.git] / lib / timespec.h

diff --git a/lib/timespec.h b/lib/timespec.h
index 70bba93..872cbb7 100644 (file)
--- a/lib/timespec.h
+++ b/lib/timespec.h
@@ -1,7 +1,7 @@
 /* timespec -- System time interface
 
-   Copyright (C) 2000, 2002, 2004-2005, 2007, 2009 Free Software Foundation,
-   Inc.
+   Copyright (C) 2000, 2002, 2004-2005, 2007, 2009-2014 Free Software
+   Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -21,19 +21,92 @@
 
 # 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
+
+/* Resolution of timespec time stamps (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 time stamp 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 time stamps.
+
+   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 "(int) (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.
+
+   The (int) cast avoids a gcc -Wconversion warning.  */
+
+_GL_TIMESPEC_INLINE int
 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);
+          : (int) (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
+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 *);
 
+_GL_INLINE_HEADER_END
+
 #endif