contrib/gmp/mpz/set_d.c

   1 /* mpz_set_d(integer, val) -- Assign INTEGER with a double value VAL.
   2
   3 Copyright 1995, 1996, 2000, 2001, 2002, 2003, 2006 Free Software Foundation,
   4 Inc.
   5
   6 This file is part of the GNU MP Library.
   7
   8 The GNU MP Library is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU Lesser General Public License as published by
  10 the Free Software Foundation; either version 3 of the License, or (at your
  11 option) any later version.
  12
  13 The GNU MP Library is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  16 License for more details.
  17
  18 You should have received a copy of the GNU Lesser General Public License
  19 along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  20
  21 #include "config.h"
  22
  23 #if HAVE_FLOAT_H
  24 #include <float.h>  /* for DBL_MAX */
  25 #endif
  26
  27 #include "gmp.h"
  28 #include "gmp-impl.h"
  29
  30
  31 /* We used to have a special case for d < MP_BASE_AS_DOUBLE, just casting
  32    double -> limb.  Unfortunately gcc 3.3 on powerpc970-apple-darwin6.8.5
  33    got this wrong.  (It assumed __fixunsdfdi returned its result in a single
  34    64-bit register, where instead that function followed the calling
  35    conventions and gave the result in two parts r3 and r4.)  Hence the use
  36    of __gmp_extract_double in all cases.  */
  37
  38 void
  39 mpz_set_d (mpz_ptr r, double d)
  40 {
  41   int negative;
  42   mp_limb_t tp[LIMBS_PER_DOUBLE];
  43   mp_ptr rp;
  44   mp_size_t rn;
  45
  46   DOUBLE_NAN_INF_ACTION (d,
  47                          __gmp_invalid_operation (),
  48                          __gmp_invalid_operation ());
  49
  50   negative = d < 0;
  51   d = ABS (d);
  52
  53   rn = __gmp_extract_double (tp, d);
  54
  55   if (ALLOC(r) < rn)
  56     _mpz_realloc (r, rn);
  57
  58   if (rn <= 0)
  59     rn = 0;
  60
  61   rp = PTR (r);
  62
  63   switch (rn)
  64     {
  65     default:
  66       MPN_ZERO (rp, rn - LIMBS_PER_DOUBLE);
  67       rp += rn - LIMBS_PER_DOUBLE;
  68       /* fall through */
  69 #if LIMBS_PER_DOUBLE == 2
  70     case 2:
  71       rp[1] = tp[1], rp[0] = tp[0];
  72       break;
  73     case 1:
  74       rp[0] = tp[1];
  75       break;
  76 #endif
  77 #if LIMBS_PER_DOUBLE == 3
  78     case 3:
  79       rp[2] = tp[2], rp[1] = tp[1], rp[0] = tp[0];
  80       break;
  81     case 2:
  82       rp[1] = tp[2], rp[0] = tp[1];
  83       break;
  84     case 1:
  85       rp[0] = tp[2];
  86       break;
  87 #endif
  88 #if LIMBS_PER_DOUBLE == 4
  89     case 4:
  90       rp[3] = tp[3], rp[2] = tp[2], rp[1] = tp[1], rp[0] = tp[0];
  91       break;
  92     case 3:
  93       rp[2] = tp[3], rp[1] = tp[2], rp[0] = tp[1];
  94       break;
  95     case 2:
  96       rp[1] = tp[3], rp[0] = tp[2];
  97       break;
  98     case 1:
  99       rp[0] = tp[3];
 100       break;
 101 #endif
 102     case 0:
 103       break;
 104     }
 105
 106   SIZ(r) = negative ? -rn : rn;
 107 }