gcc/gmp/mpz/set_d.c

/* mpz_set_d(integer, val) -- Assign INTEGER with a double value VAL.

Copyright 1995, 1996, 2000, 2001, 2002, 2003, 2006 Free Software Foundation,
Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.

The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */

#include "config.h"

#if HAVE_FLOAT_H
#include <float.h>  /* for DBL_MAX */
#endif

#include "gmp.h"
#include "gmp-impl.h"


/* We used to have a special case for d < MP_BASE_AS_DOUBLE, just casting
   double -> limb.  Unfortunately gcc 3.3 on powerpc970-apple-darwin6.8.5
   got this wrong.  (It assumed __fixunsdfdi returned its result in a single
   64-bit register, where instead that function followed the calling
   conventions and gave the result in two parts r3 and r4.)  Hence the use
   of __gmp_extract_double in all cases.  */

void
mpz_set_d (mpz_ptr r, double d)
{
  int negative;
  mp_limb_t tp[LIMBS_PER_DOUBLE];
  mp_ptr rp;
  mp_size_t rn;

  DOUBLE_NAN_INF_ACTION (d,
                         __gmp_invalid_operation (),
                         __gmp_invalid_operation ());

  negative = d < 0;
  d = ABS (d);

  rn = __gmp_extract_double (tp, d);

  if (ALLOC(r) < rn)
    _mpz_realloc (r, rn);

  if (rn <= 0)
    rn = 0;

  rp = PTR (r);

  switch (rn)
    {
    default:
      MPN_ZERO (rp, rn - LIMBS_PER_DOUBLE);
      rp += rn - LIMBS_PER_DOUBLE;
      /* fall through */
#if LIMBS_PER_DOUBLE == 2
    case 2:
      rp[1] = tp[1], rp[0] = tp[0];
      break;
    case 1:
      rp[0] = tp[1];
      break;
#endif
#if LIMBS_PER_DOUBLE == 3
    case 3:
      rp[2] = tp[2], rp[1] = tp[1], rp[0] = tp[0];
      break;
    case 2:
      rp[1] = tp[2], rp[0] = tp[1];
      break;
    case 1:
      rp[0] = tp[2];
      break;
#endif
#if LIMBS_PER_DOUBLE == 4
    case 4:
      rp[3] = tp[3], rp[2] = tp[2], rp[1] = tp[1], rp[0] = tp[0];
      break;
    case 3:
      rp[2] = tp[3], rp[1] = tp[2], rp[0] = tp[1];
      break;
    case 2:
      rp[1] = tp[3], rp[0] = tp[2];
      break;
    case 1:
      rp[0] = tp[3];
      break;
#endif
    case 0:
      break;
    }

  SIZ(r) = negative ? -rn : rn;
}