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/* mpfr_mul_ui -- multiply a floating-point number by a machine integer
Copyright (C) 1999 Free Software Foundation.
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 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 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 Library General Public
License for more details.
You should have received a copy of the GNU Library 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 <stdio.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"
#include "mpfr.h"
#include "mpfr-impl.h"
#define ONE ((mp_limb_t) 1)
void
#if __STDC__
mpfr_mul_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mp_rnd_t rnd_mode)
#else
mpfr_mul_ui (y, x, u, rnd_mode)
mpfr_ptr y;
mpfr_srcptr x;
unsigned long int u;
mp_rnd_t rnd_mode;
#endif
{
mp_limb_t carry, *my, *old_my, *my2;
unsigned long xsize, ysize, cnt, dif, ex, c;
long int sh;
TMP_DECL(marker);
if (MPFR_IS_NAN(x))
{
MPFR_CLEAR_FLAGS(y);
MPFR_SET_NAN(y);
return;
}
if (MPFR_IS_INF(x))
{
MPFR_CLEAR_FLAGS(y);
if (u)
{
MPFR_SET_INF(y);
if (MPFR_SIGN(y) != MPFR_SIGN(x)) { MPFR_CHANGE_SIGN(y); }
return;
}
else { MPFR_SET_NAN(y); return; }
}
if (MPFR_IS_ZERO(x) || !u)
{
MPFR_CLEAR_FLAGS(y); MPFR_SET_ZERO(y); return;
}
MPFR_CLEAR_FLAGS(y);
TMP_MARK(marker);
my = MPFR_MANT(y); ex = MPFR_EXP(x);
ysize = (MPFR_PREC(y) - 1) / BITS_PER_MP_LIMB + 1;
xsize = (MPFR_PREC(x) - 1) / BITS_PER_MP_LIMB + 1;
old_my = my;
if (ysize < xsize)
{
my = (mp_ptr) TMP_ALLOC (xsize * BYTES_PER_MP_LIMB);
dif = 0;
}
else
{
dif = ysize - xsize;
MPN_ZERO (my, dif);
}
carry = mpn_mul_1 (my + dif, MPFR_MANT(x), xsize, u);
/* WARNING: count_leading_zeros is undefined for carry=0 */
if (carry)
count_leading_zeros(cnt, carry);
else
cnt = BITS_PER_MP_LIMB;
/* BITS_PER_MP_LIMB - cnt is the number of significant bits in the carry */
/* the first (BITS_PER_MP_LIMB-cnt) bits of the result are in carry,
the remaining bits are in my[dif+xsize-1] .. my[dif] */
/* Warning: if all significant bits are in the carry, one has to
be careful */
if (cnt + MPFR_PREC(y) < BITS_PER_MP_LIMB)
{
/* Quick 'n dirty */
if (xsize > ysize) {
my2 = (mp_ptr) TMP_ALLOC ((xsize + 1) * BYTES_PER_MP_LIMB);
my2[xsize] = mpn_lshift(my2, my, xsize, cnt)
| (carry << (cnt ? BITS_PER_MP_LIMB - cnt : 0));
}
else {
my2 = (mp_ptr) TMP_ALLOC ((ysize + 1) * BYTES_PER_MP_LIMB);
my2[ysize] = mpn_lshift(my2, my, ysize, cnt)
| (carry << (cnt ? BITS_PER_MP_LIMB - cnt : 0));
}
my = my2; ex += BITS_PER_MP_LIMB - cnt;
carry = 0; cnt = BITS_PER_MP_LIMB;
}
/* as we already have (BITS_PER_MP_LIMB-cnt) bits in carry,
we need only prec(y) - (BITS_PER_MP_LIMB-cnt) more bits
from those in my[dif+xsize-1] .. my[dif],
and we want to store them in my[ysize-1] .. my[ysize].
Warning: the number of limbs used by x and the lower part
of y may differ */
sh = ysize - (MPFR_PREC(y) + cnt - 1) / BITS_PER_MP_LIMB;
c = mpfr_round_raw (my + sh, my + dif, MPFR_PREC(x), (MPFR_SIGN(x) < 0),
MPFR_PREC(y) - BITS_PER_MP_LIMB + cnt, rnd_mode);
/* now the high (BITS_PER_MP_LIMB-cnt) bits of the result are in carry,
and the remaining (yprec-BITS_PER_MP_LIMB+cnt) ones in
my[ysize-1] .. my[sh] */
/* If cnt = 1111111111111 and c = 1 we shall get depressed */
if (c && (carry == (ONE << (cnt ? BITS_PER_MP_LIMB - cnt : 0))
- 1))
{
cnt--;
mpn_rshift(my, my, ysize, BITS_PER_MP_LIMB - cnt);
my[ysize - 1] |= ((mp_limb_t) 1) << (BITS_PER_MP_LIMB - 1);
}
else
{
/* Warning: mpn_rshift is undefined for shift=0 */
if (cnt != BITS_PER_MP_LIMB)
mpn_rshift(my, my, ysize, BITS_PER_MP_LIMB - cnt);
my[ysize - 1] |= carry << cnt;
}
MPFR_EXP(y) = ex + BITS_PER_MP_LIMB - cnt;
if (ysize < xsize)
MPN_COPY(old_my, my, ysize);
/* set sign */
if (MPFR_SIGN(y) * MPFR_SIGN(x) < 0)
MPFR_CHANGE_SIGN(y);
TMP_FREE(marker);
}
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