source/libs/gmp/gmp-src/mpz/set_d.c

   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 }