aa9bc17601
BMakefiles and other bits will follow. Requested by: Andrey Chernov Made world by: Chuck Robey
161 lines
3.3 KiB
C
161 lines
3.3 KiB
C
/* __gmp_extract_double -- convert from double to array of mp_limb_t.
|
|
|
|
Copyright (C) 1996 Free Software Foundation, Inc.
|
|
|
|
This file is part of the GNU MP Library.
|
|
|
|
The GNU MP Library is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU Library General Public License as published by
|
|
the Free Software Foundation; either version 2 of the License, or (at your
|
|
option) any later version.
|
|
|
|
The GNU MP 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 Library General Public
|
|
License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public License
|
|
along with the GNU MP 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"
|
|
|
|
#ifdef XDEBUG
|
|
#undef _GMP_IEEE_FLOATS
|
|
#endif
|
|
|
|
#ifndef _GMP_IEEE_FLOATS
|
|
#define _GMP_IEEE_FLOATS 0
|
|
#endif
|
|
|
|
#define MP_BASE_AS_DOUBLE (2.0 * ((mp_limb_t) 1 << (BITS_PER_MP_LIMB - 1)))
|
|
|
|
/* Extract a non-negative double in d. */
|
|
|
|
int
|
|
#if __STDC__
|
|
__gmp_extract_double (mp_ptr rp, double d)
|
|
#else
|
|
__gmp_extract_double (rp, d)
|
|
mp_ptr rp;
|
|
double d;
|
|
#endif
|
|
{
|
|
long exp;
|
|
unsigned sc;
|
|
mp_limb_t manh, manl;
|
|
|
|
/* 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;
|
|
rp[1] = 0;
|
|
#if BITS_PER_MP_LIMB == 32
|
|
rp[2] = 0;
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
#if _GMP_IEEE_FLOATS
|
|
{
|
|
union ieee_double_extract x;
|
|
x.d = d;
|
|
|
|
exp = x.s.exp;
|
|
sc = (unsigned) (exp + 2) % BITS_PER_MP_LIMB;
|
|
#if BITS_PER_MP_LIMB == 64
|
|
manl = (((mp_limb_t) 1 << 63)
|
|
| ((mp_limb_t) x.s.manh << 43) | ((mp_limb_t) x.s.manl << 11));
|
|
#else
|
|
manh = ((mp_limb_t) 1 << 31) | (x.s.manh << 11) | (x.s.manl >> 21);
|
|
manl = x.s.manl << 11;
|
|
#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;
|
|
}
|
|
}
|
|
|
|
sc = (unsigned) exp % BITS_PER_MP_LIMB;
|
|
|
|
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
|
|
|
|
exp = (unsigned) (exp + 1) / BITS_PER_MP_LIMB - 1024 / BITS_PER_MP_LIMB + 1;
|
|
|
|
#if BITS_PER_MP_LIMB == 64
|
|
if (sc != 0)
|
|
{
|
|
rp[1] = manl >> (BITS_PER_MP_LIMB - sc);
|
|
rp[0] = manl << sc;
|
|
}
|
|
else
|
|
{
|
|
rp[1] = manl;
|
|
rp[0] = 0;
|
|
}
|
|
#else
|
|
if (sc != 0)
|
|
{
|
|
rp[2] = manh >> (BITS_PER_MP_LIMB - sc);
|
|
rp[1] = (manl >> (BITS_PER_MP_LIMB - sc)) | (manh << sc);
|
|
rp[0] = manl << sc;
|
|
}
|
|
else
|
|
{
|
|
rp[2] = manh;
|
|
rp[1] = manl;
|
|
rp[0] = 0;
|
|
}
|
|
#endif
|
|
|
|
return exp;
|
|
}
|