File: [local] / OpenXM_contrib / gmp / mpfr / Attic / set_d.c (download)
Revision 1.1.1.2 (vendor branch), Mon Aug 25 16:06:07 2003 UTC (21 years, 1 month ago) by ohara
Branch: GMP
CVS Tags: VERSION_4_1_2, RELEASE_1_2_3, RELEASE_1_2_2_KNOPPIX_b, RELEASE_1_2_2_KNOPPIX Changes since 1.1.1.1: +88 -188
lines
Import gmp 4.1.2
|
/* mpfr_set_d -- convert a machine double precision float to
a multiple precision floating-point number
Copyright 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
This file is part of the MPFR Library.
The MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.
The MPFR Library 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"
#include "mpfr.h"
#include "mpfr-impl.h"
#if (BITS_PER_MP_LIMB==32)
#define MPFR_LIMBS_PER_DOUBLE 2
#elif (BITS_PER_MP_LIMB >= 64)
#define MPFR_LIMBS_PER_DOUBLE 1
#elif (BITS_PER_MP_LIMB == 16)
#define MPFR_LIMBS_PER_DOUBLE 4
#endif
static int __mpfr_extract_double _PROTO ((mp_ptr, double));
/* Included from gmp-2.0.2, patched to support denorms */
#ifdef XDEBUG
#undef _GMP_IEEE_FLOATS
#endif
#ifndef _GMP_IEEE_FLOATS
#define _GMP_IEEE_FLOATS 0
#endif
static int
__mpfr_extract_double (mp_ptr rp, double d)
/* e=0 iff BITS_PER_MP_LIMB=32 and rp has only one limb */
{
long exp;
mp_limb_t manl;
#if BITS_PER_MP_LIMB == 32
mp_limb_t manh;
#endif
/* BUGS
1. Should handle Inf and NaN in IEEE specific code.
2. Handle Inf and NaN also in default code, to avoid hangs.
3. Generalize to handle all BITS_PER_MP_LIMB >= 32.
4. This lits is incomplete and misspelled.
*/
if (d == 0.0)
{
rp[0] = 0;
return 0;
}
#if _GMP_IEEE_FLOATS
{
union ieee_double_extract x;
x.d = d;
exp = x.s.exp;
if (exp)
{
#if BITS_PER_MP_LIMB == 64
manl = ((MP_LIMB_T_ONE << 63)
| ((mp_limb_t) x.s.manh << 43) | ((mp_limb_t) x.s.manl << 11));
#else
manh = (MP_LIMB_T_ONE << 31) | (x.s.manh << 11) | (x.s.manl >> 21);
manl = x.s.manl << 11;
#endif
}
else /* denormalized number */
{
#if BITS_PER_MP_LIMB == 64
manl = ((mp_limb_t) x.s.manh << 43) | ((mp_limb_t) x.s.manl << 11);
#else
manh = (x.s.manh << 11) /* high 21 bits */
| (x.s.manl >> 21); /* middle 11 bits */
manl = x.s.manl << 11; /* low 21 bits */
#endif
}
}
#else
{
/* Unknown (or known to be non-IEEE) double format. */
exp = 0;
if (d >= 1.0)
{
if (d * 0.5 == d)
abort ();
while (d >= 32768.0)
{
d *= (1.0 / 65536.0);
exp += 16;
}
while (d >= 1.0)
{
d *= 0.5;
exp += 1;
}
}
else if (d < 0.5)
{
while (d < (1.0 / 65536.0))
{
d *= 65536.0;
exp -= 16;
}
while (d < 0.5)
{
d *= 2.0;
exp -= 1;
}
}
d *= MP_BASE_AS_DOUBLE;
#if BITS_PER_MP_LIMB == 64
manl = d;
#else
manh = d;
manl = (d - manh) * MP_BASE_AS_DOUBLE;
#endif
exp += 1022;
}
#endif
if (exp) exp = (unsigned) exp - 1022; else exp = -1021;
#if BITS_PER_MP_LIMB == 64
rp[0] = manl;
#else
rp[1] = manh;
rp[0] = manl;
#endif
return exp;
}
/* End of part included from gmp-2.0.2 */
int
mpfr_set_d (mpfr_ptr r, double d, mp_rnd_t rnd_mode)
{
int signd, sizetmp, inexact;
unsigned int cnt, k;
mpfr_ptr tmp;
TMP_DECL(marker);
TMP_MARK(marker);
MPFR_CLEAR_FLAGS(r);
if (d == 0)
{
union ieee_double_extract x;
MPFR_SET_ZERO(r);
/* set correct sign */
x.d = d;
if (((x.s.sig == 1) && (MPFR_SIGN(r) > 0))
|| ((x.s.sig == 0) && (MPFR_SIGN(r) < 0)))
MPFR_CHANGE_SIGN(r);
return 0; /* 0 is exact */
}
else if (DOUBLE_ISNAN(d))
{
MPFR_SET_NAN(r);
MPFR_RET_NAN;
}
else if (DOUBLE_ISINF(d))
{
MPFR_SET_INF(r);
if ((d > 0 && (MPFR_SIGN(r) == -1)) || (d < 0 && (MPFR_SIGN(r) == 1)))
MPFR_CHANGE_SIGN(r);
return 0; /* infinity is exact */
}
/* warning: don't use tmp=r here, even if SIZE(r) >= MPFR_LIMBS_PER_DOUBLE,
since PREC(r) may be different from PREC(tmp), and then both variables
would have same precision in the mpfr_set4 call below. */
tmp = (mpfr_ptr) TMP_ALLOC(sizeof(mpfr_t));
MPFR_MANT(tmp) = TMP_ALLOC(MPFR_LIMBS_PER_DOUBLE * BYTES_PER_MP_LIMB);
MPFR_PREC(tmp) = 53;
MPFR_SIZE(tmp) = MPFR_LIMBS_PER_DOUBLE;
sizetmp = MPFR_LIMBS_PER_DOUBLE;
signd = (d < 0) ? -1 : 1;
d = ABS (d);
MPFR_EXP(tmp) = __mpfr_extract_double (MPFR_MANT(tmp), d);
/* determine number k of zero high limbs */
for (k = 0; k < sizetmp && MPFR_MANT(tmp)[sizetmp - 1 - k] == 0; k++);
count_leading_zeros (cnt, MPFR_MANT(tmp)[sizetmp - 1 - k]);
if (cnt)
mpn_lshift (MPFR_MANT(tmp) + k, MPFR_MANT(tmp), sizetmp - k, cnt);
else if (k)
MPN_COPY (MPFR_MANT(tmp) + k, MPFR_MANT(tmp), sizetmp - k);
if (k)
MPN_ZERO (MPFR_MANT(tmp), k);
MPFR_EXP(tmp) -= cnt + k * BITS_PER_MP_LIMB;
/* tmp is exact since PREC(tmp)=53 */
inexact = mpfr_set4 (r, tmp, rnd_mode, signd);
TMP_FREE(marker);
return inexact;
}