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/* mpfr_mul_ui -- multiply a floating-point number by a machine integer
Copyright 1999, 2000, 2001, 2002, 2003 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"
int
mpfr_mul_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mp_rnd_t rnd_mode)
{
mp_limb_t *yp, *old_yp;
mp_size_t xn, yn;
int cnt, c, inexact;
TMP_DECL(marker);
if (MPFR_IS_NAN(x))
{
MPFR_SET_NAN(y);
MPFR_RET_NAN;
}
if (MPFR_IS_INF(x))
{
if (u != 0)
{
MPFR_CLEAR_FLAGS(y);
MPFR_SET_INF(y);
MPFR_SET_SAME_SIGN(y, x);
MPFR_RET(0); /* infinity is exact */
}
else /* 0 * infinity */
{
MPFR_SET_NAN(y);
MPFR_RET_NAN;
}
}
MPFR_CLEAR_FLAGS(y);
if (u == 0 || MPFR_IS_ZERO(x))
{
MPFR_SET_ZERO(y);
MPFR_SET_SAME_SIGN(y, x);
MPFR_RET(0); /* zero is exact */
}
if (u == 1)
return mpfr_set (y, x, rnd_mode);
TMP_MARK(marker);
yp = MPFR_MANT(y);
yn = (MPFR_PREC(y) - 1) / BITS_PER_MP_LIMB + 1;
xn = (MPFR_PREC(x) - 1) / BITS_PER_MP_LIMB + 1;
old_yp = yp;
MPFR_ASSERTN(xn < MP_SIZE_T_MAX);
if (yn < xn + 1)
yp = (mp_ptr) TMP_ALLOC ((size_t) (xn + 1) * BYTES_PER_MP_LIMB);
MPFR_ASSERTN(u == (mp_limb_t) u);
yp[xn] = mpn_mul_1 (yp, MPFR_MANT(x), xn, u);
/* x * u is stored in yp[xn], ..., yp[0] */
/* since the case u=1 was treated above, we have u >= 2, thus
yp[xn] >= 1 since x was msb-normalized */
MPFR_ASSERTN(yp[xn] != 0);
if ((yp[xn] & MPFR_LIMB_HIGHBIT) == 0)
{
count_leading_zeros(cnt, yp[xn]);
mpn_lshift (yp, yp, xn + 1, cnt);
}
else
{
cnt = 0;
}
/* now yp[xn], ..., yp[0] is msb-normalized too, and has at most
PREC(x) + (BITS_PER_MP_LIMB - cnt) non-zero bits */
c = mpfr_round_raw (old_yp, yp, (mp_prec_t) (xn + 1) * BITS_PER_MP_LIMB,
(MPFR_SIGN(x) < 0), MPFR_PREC(y), rnd_mode, &inexact);
cnt = BITS_PER_MP_LIMB - cnt;
if (c) /* rounded result is 1.0000000000000000... */
{
old_yp[yn-1] = MPFR_LIMB_HIGHBIT;
cnt++;
}
TMP_FREE(marker);
if (__gmpfr_emax < MPFR_EMAX_MIN + cnt ||
MPFR_GET_EXP (x) > __gmpfr_emax - cnt)
return mpfr_set_overflow(y, rnd_mode, MPFR_SIGN(x));
MPFR_SET_EXP (y, MPFR_GET_EXP (x) + cnt);
MPFR_SET_SAME_SIGN(y, x);
return inexact;
}
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