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/* mpfr_set_uj -- set a MPFR number from a huge machine unsigned integer
Copyright 2004-2016 Free Software Foundation, Inc.
Contributed by the AriC and Caramba projects, INRIA.
This file is part of the GNU MPFR Library.
The GNU 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 3 of the License, or (at your
option) any later version.
The GNU 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 GNU MPFR Library; see the file COPYING.LESSER. If not, see
http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#define MPFR_NEED_LONGLONG_H
#include "mpfr-intmax.h"
#include "mpfr-impl.h"
#ifdef _MPFR_H_HAVE_INTMAX_T
#define uintmaxpml (sizeof(uintmax_t) / sizeof(mp_limb_t))
int
mpfr_set_uj (mpfr_t x, uintmax_t j, mpfr_rnd_t rnd)
{
return mpfr_set_uj_2exp (x, j, 0, rnd);
}
int
mpfr_set_uj_2exp (mpfr_t x, uintmax_t j, intmax_t e, mpfr_rnd_t rnd)
{
int cnt;
mp_size_t i, k;
mp_limb_t limb;
mp_limb_t yp[uintmaxpml];
mpfr_t y;
unsigned long uintmax_bit_size = sizeof(uintmax_t) * CHAR_BIT;
unsigned long bpml = GMP_NUMB_BITS % uintmax_bit_size;
/* Special case */
if (j == 0)
{
MPFR_SET_POS(x);
MPFR_SET_ZERO(x);
MPFR_RET(0);
}
MPFR_ASSERTN (sizeof(uintmax_t) % sizeof(mp_limb_t) == 0);
/* Create an auxiliary var */
MPFR_TMP_INIT1 (yp, y, uintmax_bit_size);
/* The compiler will optimize the code by removing the useless branch. */
k = uintmaxpml;
if (uintmaxpml == 1)
{
limb = j;
count_leading_zeros(cnt, limb);
/* Normalize the most significant limb */
yp[0] = limb << cnt;
}
else
{
mp_size_t len;
/* Note: either GMP_NUMB_BITS = uintmax_bit_size, then k = 1 the
shift j >>= bpml is never done, or GMP_NUMB_BITS < uintmax_bit_size
and bpml = GMP_NUMB_BITS. */
for (i = 0; i < k; i++, j >>= bpml)
yp[i] = j; /* Only the low bits are copied */
/* Find the first limb not equal to zero. */
do
{
MPFR_ASSERTD (k > 0);
limb = yp[--k];
}
while (limb == 0);
k++;
len = numberof (yp) - k;
count_leading_zeros(cnt, limb);
/* Normalize it: len = number of last zero limbs,
k = number of previous limbs */
if (MPFR_LIKELY (cnt != 0))
mpn_lshift (yp+len, yp, k, cnt); /* Normalize the high limb */
else if (len != 0)
MPN_COPY_DECR (yp+len, yp, k); /* Must use DECR */
if (len != 0)
{
if (len == 1)
yp[0] = MPFR_LIMB_ZERO;
else
MPN_ZERO (yp, len); /* Zero the last limbs */
}
}
e += k * GMP_NUMB_BITS - cnt; /* Update Expo */
MPFR_ASSERTD (MPFR_LIMB_MSB(yp[numberof (yp) - 1]) != 0);
/* Check expo underflow / overflow (can't use mpfr_check_range) */
if (MPFR_UNLIKELY(e < __gmpfr_emin))
{
/* The following test is necessary because in the rounding to the
* nearest mode, mpfr_underflow always rounds away from 0. In
* this rounding mode, we need to round to 0 if:
* _ |x| < 2^(emin-2), or
* _ |x| = 2^(emin-2) and the absolute value of the exact
* result is <= 2^(emin-2). */
if (rnd == MPFR_RNDN && (e+1 < __gmpfr_emin || mpfr_powerof2_raw(y)))
rnd = MPFR_RNDZ;
return mpfr_underflow (x, rnd, MPFR_SIGN_POS);
}
if (MPFR_UNLIKELY(e > __gmpfr_emax))
return mpfr_overflow (x, rnd, MPFR_SIGN_POS);
MPFR_SET_EXP (y, e);
/* Final: set x to y (rounding if necessary) */
return mpfr_set (x, y, rnd);
}
#endif
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