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

     1  /* mpq_set_d(mpq_t q, double d) -- Set q to d without rounding.
     2  
     3  Copyright 2000, 2002, 2003, 2012, 2014 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  #include "longlong.h"
    40  
    41  #if LIMBS_PER_DOUBLE > 4
    42    choke me
    43  #endif
    44  
    45  void
    46  mpq_set_d (mpq_ptr dest, double d)
    47  {
    48    int negative;
    49    mp_exp_t exp;
    50    mp_limb_t tp[LIMBS_PER_DOUBLE];
    51    mp_ptr np, dp;
    52    mp_size_t nn, dn;
    53    int c;
    54  
    55    DOUBLE_NAN_INF_ACTION (d,
    56                           __gmp_invalid_operation (),
    57                           __gmp_invalid_operation ());
    58  
    59    negative = d < 0;
    60    d = ABS (d);
    61  
    62    exp = __gmp_extract_double (tp, d);
    63  
    64    /* There are two main version of the conversion.  The `then' arm handles
    65       numbers with a fractional part, while the `else' arm handles integers.  */
    66  #if LIMBS_PER_DOUBLE == 4
    67    if (exp <= 1 || (exp == 2 && (tp[0] | tp[1]) != 0))
    68  #endif
    69  #if LIMBS_PER_DOUBLE == 3
    70    if (exp <= 1 || (exp == 2 && tp[0] != 0))
    71  #endif
    72  #if LIMBS_PER_DOUBLE == 2
    73    if (exp <= 1)
    74  #endif
    75      {
    76        if (d == 0.0)
    77  	{
    78  	  SIZ(NUM(dest)) = 0;
    79  	  SIZ(DEN(dest)) = 1;
    80  	  PTR(DEN(dest))[0] = 1;
    81  	  return;
    82  	}
    83  
    84  #if LIMBS_PER_DOUBLE == 4
    85        np = MPZ_NEWALLOC (NUM(dest), 4);
    86        if ((tp[0] | tp[1] | tp[2]) == 0)
    87  	np[0] = tp[3], nn = 1;
    88        else if ((tp[0] | tp[1]) == 0)
    89  	np[1] = tp[3], np[0] = tp[2], nn = 2;
    90        else if (tp[0] == 0)
    91  	np[2] = tp[3], np[1] = tp[2], np[0] = tp[1], nn = 3;
    92        else
    93  	np[3] = tp[3], np[2] = tp[2], np[1] = tp[1], np[0] = tp[0], nn = 4;
    94  #endif
    95  #if LIMBS_PER_DOUBLE == 3
    96        np = MPZ_NEWALLOC (NUM(dest), 3);
    97        if ((tp[0] | tp[1]) == 0)
    98  	np[0] = tp[2], nn = 1;
    99        else if (tp[0] == 0)
   100  	np[1] = tp[2], np[0] = tp[1], nn = 2;
   101        else
   102  	np[2] = tp[2], np[1] = tp[1], np[0] = tp[0], nn = 3;
   103  #endif
   104  #if LIMBS_PER_DOUBLE == 2
   105        np = MPZ_NEWALLOC (NUM(dest), 2);
   106        if (tp[0] == 0)
   107  	np[0] = tp[1], nn = 1;
   108        else
   109  	np[1] = tp[1], np[0] = tp[0], nn = 2;
   110  #endif
   111        dn = nn + 1 - exp;
   112        ASSERT (dn > 0); /* -exp >= -1; nn >= 1*/
   113        dp = MPZ_NEWALLOC (DEN(dest), dn);
   114        MPN_ZERO (dp, dn - 1);
   115        dp[dn - 1] = 1;
   116        count_trailing_zeros (c, np[0] | dp[0]);
   117        if (c != 0)
   118  	{
   119  	  mpn_rshift (np, np, nn, c);
   120  	  nn -= np[nn - 1] == 0;
   121  	  --dn;
   122  	  dp[dn - 1] = CNST_LIMB(1) << (GMP_LIMB_BITS - c);
   123  	}
   124        SIZ(DEN(dest)) = dn;
   125      }
   126    else
   127      {
   128        nn = exp;
   129        np = MPZ_NEWALLOC (NUM(dest), nn);
   130        switch (nn)
   131          {
   132  	default:
   133  	  MPN_ZERO (np, nn - LIMBS_PER_DOUBLE);
   134  	  np += nn - LIMBS_PER_DOUBLE;
   135  	  /* fall through */
   136  #if LIMBS_PER_DOUBLE == 2
   137  	case 2:
   138  	  np[1] = tp[1], np[0] = tp[0];
   139  	  break;
   140  #endif
   141  #if LIMBS_PER_DOUBLE == 3
   142  	case 3:
   143  	  np[2] = tp[2], np[1] = tp[1], np[0] = tp[0];
   144  	  break;
   145  	case 2:
   146  	  np[1] = tp[2], np[0] = tp[1];
   147  	  break;
   148  #endif
   149  #if LIMBS_PER_DOUBLE == 4
   150  	case 4:
   151  	  np[3] = tp[3], np[2] = tp[2], np[1] = tp[1], np[0] = tp[0];
   152  	  break;
   153  	case 3:
   154  	  np[2] = tp[3], np[1] = tp[2], np[0] = tp[1];
   155  	  break;
   156  	case 2:
   157  	  np[1] = tp[3], np[0] = tp[2];
   158  	  break;
   159  #endif
   160  	}
   161        *PTR(DEN(dest)) = 1;
   162        SIZ(DEN(dest)) = 1;
   163      }
   164    SIZ(NUM(dest)) = negative ? -nn : nn;
   165  }