/* Round towards zero.
- Copyright (C) 2007 Free Software Foundation, Inc.
+ Copyright (C) 2007, 2010-2013 Free Software Foundation, Inc.
- This program is free software; you can redistribute it and/or modify
+ 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 2, or (at your option)
- any later version.
+ 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, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+ 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 Bruno Haible <bruno@clisp.org>, 2007. */
-#include <config.h>
+#if ! defined USE_LONG_DOUBLE
+# include <config.h>
+#endif
/* Specification. */
#include <math.h>
#include <float.h>
+#undef MIN
+
#ifdef USE_LONG_DOUBLE
# define FUNC truncl
# define DOUBLE long double
# define MANT_DIG LDBL_MANT_DIG
+# define MIN LDBL_MIN
# define L_(literal) literal##L
#elif ! defined USE_FLOAT
# define FUNC trunc
# define DOUBLE double
# define MANT_DIG DBL_MANT_DIG
+# define MIN DBL_MIN
# define L_(literal) literal
#else /* defined USE_FLOAT */
# define FUNC truncf
# define DOUBLE float
# define MANT_DIG FLT_MANT_DIG
+# define MIN FLT_MIN
# define L_(literal) literal##f
#endif
+/* -0.0. See minus-zero.h. */
+#if defined __hpux || defined __sgi || defined __ICC
+# define MINUS_ZERO (-MIN * MIN)
+#else
+# define MINUS_ZERO L_(-0.0)
+#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 =
+static const DOUBLE TWO_MANT_DIG =
/* Assume MANT_DIG <= 5 * 31.
Use the identity
n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */
if (z > L_(0.0))
{
- /* 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);
+ /* 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))
{
- /* Round to the next integer (nearest or up or down, doesn't matter). */
- z -= TWO_MANT_DIG;
- z += TWO_MANT_DIG;
- /* Enforce rounding up. */
- if (z < y)
- z += L_(1.0);
+ /* For -1 < x < 0, return -0.0 regardless of the current rounding
+ mode. */
+ if (z > L_(-1.0))
+ z = MINUS_ZERO;
+ /* 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 up. */
+ if (z < y)
+ z += L_(1.0);
+ }
}
return z;
}