github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpz/set_d.c (about)

     1  /* mpz_set_d(integer, val) -- Assign INTEGER with a double value VAL.
     2  
     3  Copyright 1995, 1996, 2000-2003, 2006 Free Software Foundation, Inc.
     4  
     5  This file is part of the GNU MP Library.
     6  
     7  The GNU MP Library is free software; you can redistribute it and/or modify
     8  it under the terms of either:
     9  
    10    * the GNU Lesser General Public License as published by the Free
    11      Software Foundation; either version 3 of the License, or (at your
    12      option) any later version.
    13  
    14  or
    15  
    16    * the GNU General Public License as published by the Free Software
    17      Foundation; either version 2 of the License, or (at your option) any
    18      later version.
    19  
    20  or both in parallel, as here.
    21  
    22  The GNU MP Library is distributed in the hope that it will be useful, but
    23  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    24  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    25  for more details.
    26  
    27  You should have received copies of the GNU General Public License and the
    28  GNU Lesser General Public License along with the GNU MP Library.  If not,
    29  see https://www.gnu.org/licenses/.  */
    30  
    31  #include "config.h"
    32  
    33  #if HAVE_FLOAT_H
    34  #include <float.h>  /* for DBL_MAX */
    35  #endif
    36  
    37  #include "gmp.h"
    38  #include "gmp-impl.h"
    39  
    40  
    41  /* We used to have a special case for d < MP_BASE_AS_DOUBLE, just casting
    42     double -> limb.  Unfortunately gcc 3.3 on powerpc970-apple-darwin6.8.5
    43     got this wrong.  (It assumed __fixunsdfdi returned its result in a single
    44     64-bit register, where instead that function followed the calling
    45     conventions and gave the result in two parts r3 and r4.)  Hence the use
    46     of __gmp_extract_double in all cases.  */
    47  
    48  void
    49  mpz_set_d (mpz_ptr r, double d)
    50  {
    51    int negative;
    52    mp_limb_t tp[LIMBS_PER_DOUBLE];
    53    mp_ptr rp;
    54    mp_size_t rn;
    55  
    56    DOUBLE_NAN_INF_ACTION (d,
    57  			 __gmp_invalid_operation (),
    58  			 __gmp_invalid_operation ());
    59  
    60    negative = d < 0;
    61    d = ABS (d);
    62  
    63    rn = __gmp_extract_double (tp, d);
    64  
    65    if (ALLOC(r) < rn)
    66      _mpz_realloc (r, rn);
    67  
    68    if (rn <= 0)
    69      rn = 0;
    70  
    71    rp = PTR (r);
    72  
    73    switch (rn)
    74      {
    75      default:
    76        MPN_ZERO (rp, rn - LIMBS_PER_DOUBLE);
    77        rp += rn - LIMBS_PER_DOUBLE;
    78        /* fall through */
    79  #if LIMBS_PER_DOUBLE == 2
    80      case 2:
    81        rp[1] = tp[1], rp[0] = tp[0];
    82        break;
    83      case 1:
    84        rp[0] = tp[1];
    85        break;
    86  #endif
    87  #if LIMBS_PER_DOUBLE == 3
    88      case 3:
    89        rp[2] = tp[2], rp[1] = tp[1], rp[0] = tp[0];
    90        break;
    91      case 2:
    92        rp[1] = tp[2], rp[0] = tp[1];
    93        break;
    94      case 1:
    95        rp[0] = tp[2];
    96        break;
    97  #endif
    98  #if LIMBS_PER_DOUBLE == 4
    99      case 4:
   100        rp[3] = tp[3], rp[2] = tp[2], rp[1] = tp[1], rp[0] = tp[0];
   101        break;
   102      case 3:
   103        rp[2] = tp[3], rp[1] = tp[2], rp[0] = tp[1];
   104        break;
   105      case 2:
   106        rp[1] = tp[3], rp[0] = tp[2];
   107        break;
   108      case 1:
   109        rp[0] = tp[3];
   110        break;
   111  #endif
   112      case 0:
   113        break;
   114      }
   115  
   116    SIZ(r) = negative ? -rn : rn;
   117  }