efee5258bc
The MPFR library is a C library for multiple-precision floating-point computations with exact rounding (also called correct rounding). It is based on the GMP multiple-precision library and should replace the MPF class in further releases of GMP. GCC >= 4.2 requires MPFR.
138 lines
4.2 KiB
C
138 lines
4.2 KiB
C
/* mpfr_set_uj -- set a MPFR number from a huge machine unsigned integer
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Copyright 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
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Contributed by the Arenaire and Cacao projects, INRIA.
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This file is part of the GNU MPFR Library.
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The GNU MPFR Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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The GNU MPFR Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
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http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
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51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
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#ifdef HAVE_CONFIG_H
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# include "config.h" /* for a build within gmp */
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#endif
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/* The ISO C99 standard specifies that in C++ implementations the
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INTMAX_MAX, ... macros should only be defined if explicitly requested. */
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#if defined(__cplusplus)
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# define __STDC_LIMIT_MACROS
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# define __STDC_CONSTANT_MACROS
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#endif
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#if HAVE_INTTYPES_H
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# include <inttypes.h> /* for intmax_t */
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#else
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# if HAVE_STDINT_H
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# include <stdint.h>
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# endif
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#endif
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#define MPFR_NEED_LONGLONG_H
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#include "mpfr-impl.h"
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#ifdef _MPFR_H_HAVE_INTMAX_T
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int
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mpfr_set_uj (mpfr_t x, uintmax_t j, mpfr_rnd_t rnd)
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{
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return mpfr_set_uj_2exp (x, j, 0, rnd);
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}
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int
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mpfr_set_uj_2exp (mpfr_t x, uintmax_t j, intmax_t e, mpfr_rnd_t rnd)
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{
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unsigned int cnt, i;
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mp_size_t k, len;
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mp_limb_t limb;
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mp_limb_t yp[sizeof(uintmax_t) / sizeof(mp_limb_t)];
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mpfr_t y;
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unsigned long uintmax_bit_size = sizeof(uintmax_t) * CHAR_BIT;
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unsigned long bpml = GMP_NUMB_BITS % uintmax_bit_size;
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/* Special case */
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if (j == 0)
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{
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MPFR_SET_POS(x);
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MPFR_SET_ZERO(x);
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MPFR_RET(0);
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}
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MPFR_ASSERTN (sizeof(uintmax_t) % sizeof(mp_limb_t) == 0);
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/* Create an auxillary var */
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MPFR_TMP_INIT1 (yp, y, uintmax_bit_size);
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k = numberof (yp);
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if (k == 1)
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limb = yp[0] = j;
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else
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{
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/* Note: either GMP_NUMB_BITS = uintmax_bit_size, then k = 1 the
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shift j >>= bpml is never done, or GMP_NUMB_BITS < uintmax_bit_size
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and bpml = GMP_NUMB_BITS. */
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for (i = 0; i < k; i++, j >>= bpml)
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yp[i] = j; /* Only the low bits are copied */
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/* Find the first limb not equal to zero. */
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do
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{
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MPFR_ASSERTD (k > 0);
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limb = yp[--k];
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}
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while (limb == 0);
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k++;
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}
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count_leading_zeros(cnt, limb);
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len = numberof (yp) - k;
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/* Normalize it: len = number of last 0 limb, k number of non-zero limbs */
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if (MPFR_LIKELY(cnt))
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mpn_lshift (yp+len, yp, k, cnt); /* Normalize the High Limb*/
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else if (len != 0)
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MPN_COPY_DECR (yp+len, yp, k); /* Must use DECR */
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if (len != 0)
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/* Note: when numberof(yp)==1, len is constant and null, so the compiler
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can optimize out this code. */
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{
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if (len == 1)
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yp[0] = (mp_limb_t) 0;
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else
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MPN_ZERO (yp, len); /* Zeroing the last limbs */
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}
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e += k * GMP_NUMB_BITS - cnt; /* Update Expo */
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MPFR_ASSERTD (MPFR_LIMB_MSB(yp[numberof (yp) - 1]) != 0);
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/* Check expo underflow / overflow (can't use mpfr_check_range) */
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if (MPFR_UNLIKELY(e < __gmpfr_emin))
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{
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/* The following test is necessary because in the rounding to the
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* nearest mode, mpfr_underflow always rounds away from 0. In
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* this rounding mode, we need to round to 0 if:
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* _ |x| < 2^(emin-2), or
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* _ |x| = 2^(emin-2) and the absolute value of the exact
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* result is <= 2^(emin-2). */
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if (rnd == MPFR_RNDN && (e+1 < __gmpfr_emin || mpfr_powerof2_raw(y)))
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rnd = MPFR_RNDZ;
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return mpfr_underflow (x, rnd, MPFR_SIGN_POS);
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}
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if (MPFR_UNLIKELY(e > __gmpfr_emax))
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return mpfr_overflow (x, rnd, MPFR_SIGN_POS);
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MPFR_SET_EXP (y, e);
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/* Final: set x to y (rounding if necessary) */
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return mpfr_set (x, y, rnd);
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}
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#endif
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