/* Split a double into fraction and mantissa.
- Copyright (C) 2007 Free Software Foundation, Inc.
+ Copyright (C) 2007-2013 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/>. */
-#include <config.h>
+/* Written by Paolo Bonzini <bonzini@gnu.org>, 2003, and
+ Bruno Haible <bruno@clisp.org>, 2007. */
-#if !(defined USE_LONG_DOUBLE && !HAVE_LONG_DOUBLE)
+#if ! defined USE_LONG_DOUBLE
+# include <config.h>
+#endif
/* Specification. */
-# include <math.h>
+#include <math.h>
-# include <float.h>
-# ifdef USE_LONG_DOUBLE
-# include "isnanl-nolibm.h"
-# else
-# include "isnan.h"
-# endif
+#include <float.h>
+#ifdef USE_LONG_DOUBLE
+# include "isnanl-nolibm.h"
+# include "fpucw.h"
+#else
+# include "isnand-nolibm.h"
+#endif
/* This file assumes FLT_RADIX = 2. If FLT_RADIX is a power of 2 greater
than 2, or not even a power of 2, some rounding errors can occur, so that
then the returned mantissa is only guaranteed to be <= 1.0, not < 1.0. */
-# ifdef USE_LONG_DOUBLE
-# define FUNC frexpl
-# define DOUBLE long double
-# define ISNAN isnanl
-# define L_(literal) literal##L
-# else
-# define FUNC frexp
-# define DOUBLE double
-# define ISNAN isnan
-# define L_(literal) literal
-# endif
+#ifdef USE_LONG_DOUBLE
+# define FUNC frexpl
+# define DOUBLE long double
+# define ISNAN isnanl
+# define DECL_ROUNDING DECL_LONG_DOUBLE_ROUNDING
+# define BEGIN_ROUNDING() BEGIN_LONG_DOUBLE_ROUNDING ()
+# define END_ROUNDING() END_LONG_DOUBLE_ROUNDING ()
+# define L_(literal) literal##L
+#else
+# define FUNC frexp
+# define DOUBLE double
+# define ISNAN isnand
+# define DECL_ROUNDING
+# define BEGIN_ROUNDING()
+# define END_ROUNDING()
+# define L_(literal) literal
+#endif
DOUBLE
-FUNC (DOUBLE x, int *exp)
+FUNC (DOUBLE x, int *expptr)
{
int sign;
int exponent;
+ DECL_ROUNDING
/* Test for NaN, infinity, and zero. */
if (ISNAN (x) || x + x == x)
{
- *exp = 0;
+ *expptr = 0;
return x;
}
sign = -1;
}
- if (0)
- {
- /* Implementation contributed by Paolo Bonzini.
- Disabled because it's under GPL and doesn't pass the tests. */
-
- /* Since the exponent is an 'int', it fits in 64 bits. Therefore the
- loops are executed no more than 64 times. */
- DOUBLE exponents[64];
- DOUBLE *next;
- int bit;
-
- exponent = 0;
- if (x >= L_(1.0))
- {
- for (next = exponents, exponents[0] = L_(2.0), bit = 1;
- *next <= x + x;
- bit <<= 1, next[1] = next[0] * next[0], next++);
-
- for (; next >= exponents; bit >>= 1, next--)
- if (x + x >= *next)
- {
- x /= *next;
- exponent |= bit;
- }
- }
- else if (x < L_(0.5))
- {
- for (next = exponents, exponents[0] = L_(0.5), bit = 1;
- *next > x;
- bit <<= 1, next[1] = next[0] * next[0], next++);
-
- for (; next >= exponents; bit >>= 1, next--)
- if (x < *next)
- {
- x /= *next;
- exponent |= bit;
- }
- exponent = - exponent;
- }
- }
- else
- {
- /* Implementation contributed by Bruno Haible. */
-
- /* Since the exponent is an 'int', it fits in 64 bits. Therefore the
- loops are executed no more than 64 times. */
- DOUBLE pow2[64]; /* pow2[i] = 2^2^i */
- DOUBLE powh[64]; /* powh[i] = 2^-2^i */
- int i;
-
- exponent = 0;
- if (x >= L_(1.0))
- {
- /* A positive exponent. */
- DOUBLE pow2_i; /* = pow2[i] */
- DOUBLE powh_i; /* = powh[i] */
-
- /* Invariants: pow2_i = 2^2^i, powh_i = 2^-2^i,
- x * 2^exponent = argument, x >= 1.0. */
- for (i = 0, pow2_i = L_(2.0), powh_i = L_(0.5);
- ;
- i++, pow2_i = pow2_i * pow2_i, powh_i = powh_i * powh_i)
- {
- if (x >= pow2_i)
- {
- exponent += (1 << i);
- x *= powh_i;
- }
- else
- break;
-
- pow2[i] = pow2_i;
- powh[i] = powh_i;
- }
- /* Avoid making x too small, as it could become a denormalized
- number and thus lose precision. */
- while (i > 0 && x < pow2[i - 1])
- {
- i--;
- powh_i = powh[i];
- }
- exponent += (1 << i);
- x *= powh_i;
- /* Here 2^-2^i <= x < 1.0. */
- }
- else
- {
- /* A negative or zero exponent. */
- DOUBLE pow2_i; /* = pow2[i] */
- DOUBLE powh_i; /* = powh[i] */
-
- /* Invariants: pow2_i = 2^2^i, powh_i = 2^-2^i,
- x * 2^exponent = argument, x < 1.0. */
- for (i = 0, pow2_i = L_(2.0), powh_i = L_(0.5);
- ;
- i++, pow2_i = pow2_i * pow2_i, powh_i = powh_i * powh_i)
- {
- if (x < powh_i)
- {
- exponent -= (1 << i);
- x *= pow2_i;
- }
- else
- break;
-
- pow2[i] = pow2_i;
- powh[i] = powh_i;
- }
- /* Here 2^-2^i <= x < 1.0. */
- }
-
- /* Invariants: x * 2^exponent = argument, and 2^-2^i <= x < 1.0. */
- while (i > 0)
- {
- i--;
- if (x < powh[i])
- {
- exponent -= (1 << i);
- x *= pow2[i];
- }
- }
- /* Here 0.5 <= x < 1.0. */
- }
-
- *exp = exponent;
- return (sign < 0 ? - x : x);
+ BEGIN_ROUNDING ();
+
+ {
+ /* Since the exponent is an 'int', it fits in 64 bits. Therefore the
+ loops are executed no more than 64 times. */
+ DOUBLE pow2[64]; /* pow2[i] = 2^2^i */
+ DOUBLE powh[64]; /* powh[i] = 2^-2^i */
+ int i;
+
+ exponent = 0;
+ if (x >= L_(1.0))
+ {
+ /* A positive exponent. */
+ DOUBLE pow2_i; /* = pow2[i] */
+ DOUBLE powh_i; /* = powh[i] */
+
+ /* Invariants: pow2_i = 2^2^i, powh_i = 2^-2^i,
+ x * 2^exponent = argument, x >= 1.0. */
+ for (i = 0, pow2_i = L_(2.0), powh_i = L_(0.5);
+ ;
+ i++, pow2_i = pow2_i * pow2_i, powh_i = powh_i * powh_i)
+ {
+ if (x >= pow2_i)
+ {
+ exponent += (1 << i);
+ x *= powh_i;
+ }
+ else
+ break;
+
+ pow2[i] = pow2_i;
+ powh[i] = powh_i;
+ }
+ /* Avoid making x too small, as it could become a denormalized
+ number and thus lose precision. */
+ while (i > 0 && x < pow2[i - 1])
+ {
+ i--;
+ powh_i = powh[i];
+ }
+ exponent += (1 << i);
+ x *= powh_i;
+ /* Here 2^-2^i <= x < 1.0. */
+ }
+ else
+ {
+ /* A negative or zero exponent. */
+ DOUBLE pow2_i; /* = pow2[i] */
+ DOUBLE powh_i; /* = powh[i] */
+
+ /* Invariants: pow2_i = 2^2^i, powh_i = 2^-2^i,
+ x * 2^exponent = argument, x < 1.0. */
+ for (i = 0, pow2_i = L_(2.0), powh_i = L_(0.5);
+ ;
+ i++, pow2_i = pow2_i * pow2_i, powh_i = powh_i * powh_i)
+ {
+ if (x < powh_i)
+ {
+ exponent -= (1 << i);
+ x *= pow2_i;
+ }
+ else
+ break;
+
+ pow2[i] = pow2_i;
+ powh[i] = powh_i;
+ }
+ /* Here 2^-2^i <= x < 1.0. */
+ }
+
+ /* Invariants: x * 2^exponent = argument, and 2^-2^i <= x < 1.0. */
+ while (i > 0)
+ {
+ i--;
+ if (x < powh[i])
+ {
+ exponent -= (1 << i);
+ x *= pow2[i];
+ }
+ }
+ /* Here 0.5 <= x < 1.0. */
+ }
+
+ if (sign < 0)
+ x = - x;
+
+ END_ROUNDING ();
+
+ *expptr = exponent;
+ return x;
}
-
-#else
-
-/* This declaration is solely to ensure that after preprocessing
- this file is never empty. */
-typedef int dummy;
-
-#endif
projects / gnulib.git / blobdiff