/* Round towards negative infinity.
- Copyright (C) 2007 Free Software Foundation, Inc.
+ Copyright (C) 2007, 2010-2012 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
/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
-#include <config.h>
+#if ! defined USE_LONG_DOUBLE
+# include <config.h>
+#endif
/* Specification. */
#include <math.h>
# define L_(literal) literal##f
#endif
+/* MSVC with option -fp:strict refuses to compile constant initializers that
+ contain floating-point operations. Pacify this compiler. */
+#ifdef _MSC_VER
+# pragma fenv_access (off)
+#endif
+
/* 2^(MANT_DIG-1). */
static const DOUBLE TWO_MANT_DIG =
/* Assume MANT_DIG <= 5 * 31.
volatile DOUBLE y = x;
volatile DOUBLE z = y;
- /* Round to the next integer (nearest or up or down, doesn't matter). */
if (z > L_(0.0))
{
- z += TWO_MANT_DIG;
- z -= TWO_MANT_DIG;
+ /* For 0 < x < 1, return +0.0 even if the current rounding mode is
+ FE_DOWNWARD. */
+ if (z < L_(1.0))
+ z = L_(0.0);
+ /* Avoid rounding errors for values near 2^k, where k >= MANT_DIG-1. */
+ else if (z < TWO_MANT_DIG)
+ {
+ /* Round to the next integer (nearest or up or down, doesn't matter). */
+ z += TWO_MANT_DIG;
+ z -= TWO_MANT_DIG;
+ /* Enforce rounding down. */
+ if (z > y)
+ z -= L_(1.0);
+ }
}
else if (z < L_(0.0))
{
- z -= TWO_MANT_DIG;
- z += TWO_MANT_DIG;
+ /* Avoid rounding errors for values near -2^k, where k >= MANT_DIG-1. */
+ if (z > - TWO_MANT_DIG)
+ {
+ /* Round to the next integer (nearest or up or down, doesn't matter). */
+ z -= TWO_MANT_DIG;
+ z += TWO_MANT_DIG;
+ /* Enforce rounding down. */
+ if (z > y)
+ z -= L_(1.0);
+ }
}
- /* Enforce rounding down. */
- if (z > y)
- z -= L_(1.0);
-
return z;
}