From 2deeabadbd2d7eaebc49d62f818e60f40159b0ff Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Thu, 30 Jun 2011 15:14:25 -0700
Subject: [PATCH] dtotimespec: new module

* lib/timespec.h (dtotimespec): New decl.
* lib/dtotimespec.c, modules/dtotimespec: New files.
---
 ChangeLog           |  4 +++
 lib/dtotimespec.c   | 69 +++++++++++++++++++++++++++++++++++++++++++++
 lib/timespec.h      |  2 ++
 modules/dtotimespec | 25 ++++++++++++++++
 4 files changed, 100 insertions(+)
 create mode 100644 lib/dtotimespec.c
 create mode 100644 modules/dtotimespec

diff --git a/ChangeLog b/ChangeLog
index 0f37252610..d20588f19e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2011-06-30  Paul Eggert  <eggert@cs.ucla.edu>
 
+	dtotimespec: new module
+	* lib/timespec.h (dtotimespec): New decl.
+	* lib/dtotimespec.c, modules/dtotimespec: New files.
+
 	* lib/timespec.h (timespec_sign, timespectod): New inline functions.
 
 	pselect: new module
diff --git a/lib/dtotimespec.c b/lib/dtotimespec.c
new file mode 100644
index 0000000000..ea0470a785
--- /dev/null
+++ b/lib/dtotimespec.c
@@ -0,0 +1,69 @@
+/* Convert double to timespec.
+
+   Copyright (C) 2011 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
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 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/>.  */
+
+/* written by Paul Eggert */
+
+/* Convert the double value SEC to a struct timespec.  Round toward
+   positive infinity.  On overflow, return an extremal value.  */
+
+#include <config.h>
+
+#include "timespec.h"
+
+#include "intprops.h"
+
+struct timespec
+dtotimespec (double sec)
+{
+  enum { BILLION = 1000 * 1000 * 1000 };
+  double min_representable = TYPE_MINIMUM (time_t);
+  double max_representable =
+    ((TYPE_MAXIMUM (time_t) * (double) BILLION + (BILLION - 1))
+     / BILLION);
+  struct timespec r;
+
+  if (! (min_representable < sec))
+    {
+      r.tv_sec = TYPE_MINIMUM (time_t);
+      r.tv_nsec = 0;
+    }
+  else if (! (sec < max_representable))
+    {
+      r.tv_sec = TYPE_MAXIMUM (time_t);
+      r.tv_nsec = BILLION - 1;
+    }
+  else
+    {
+      time_t s = sec;
+      double frac = BILLION * (sec - s);
+      long ns = frac;
+      ns += ns < frac;
+      s += ns / BILLION;
+      ns %= BILLION;
+
+      if (ns < 0)
+        {
+          s--;
+          ns += BILLION;
+        }
+
+      r.tv_sec = s;
+      r.tv_nsec = ns;
+    }
+
+  return r;
+}
diff --git a/lib/timespec.h b/lib/timespec.h
index 071f3a1fbc..191cf0660c 100644
--- a/lib/timespec.h
+++ b/lib/timespec.h
@@ -65,6 +65,8 @@ timespec_sign (struct timespec a)
   return a.tv_sec < 0 ? -1 : a.tv_sec || a.tv_nsec;
 }
 
+struct timespec dtotimespec (double);
+
 /* Return an approximation to A, of type 'double'.  */
 static inline double
 timespectod (struct timespec a)
diff --git a/modules/dtotimespec b/modules/dtotimespec
new file mode 100644
index 0000000000..d5705916cb
--- /dev/null
+++ b/modules/dtotimespec
@@ -0,0 +1,25 @@
+Description:
+Convert double to timespec.
+
+Files:
+lib/dtotimespec.c
+
+Depends-on:
+intprops
+timespec
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += dtotimespec.c
+
+Include:
+"timespec.h"
+
+Link:
+
+License:
+GPL
+
+Maintainer:
+Paul Eggert, Jim Meyering
-- 
2.30.2