/* mpq_set_d(mpq_t q, double d) -- Set q to d without rounding.

Copyright (C) 2000 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 2.1 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; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */

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

#if BITS_PER_MP_LIMB != 32 && BITS_PER_MP_LIMB != 64
This file does not handle any the used BITS_PER_MP_LIMB.
#endif

void
#if __STDC__
mpq_set_d (mpq_ptr dest, double d)
#else
mpq_set_d (dest, d)
     mpq_ptr dest;
     double d;
#endif
{
  int negative;
  mp_exp_t exp;
  mp_limb_t tp[3];
  mp_ptr np, dp;
  mp_size_t nn, dn;
  int c;

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

  exp = __gmp_extract_double (tp, d);

  /* There are two main version of the conversion.  The `then' arm handles
     things that have a fractional part, while the `else' part handles
     only integers.  */
#if BITS_PER_MP_LIMB == 32
  if (exp <= 1 || (exp == 2 && tp[0] != 0))
#else
  if (exp <= 1)
#endif
    {
      if (d == 0.0)
	{
	  SIZ(&(dest->_mp_num)) = 0;
	  SIZ(&(dest->_mp_den)) = 1;
	  PTR(&(dest->_mp_den))[0] = 1;
	  return;
	}

      dn = -exp;
      if (dest->_mp_num._mp_alloc < 3)
	_mpz_realloc (&(dest->_mp_num), 3);
      np = PTR(&(dest->_mp_num));
#if BITS_PER_MP_LIMB == 32
      if ((tp[0] | tp[1]) == 0)
	np[0] = tp[2], nn = 1;
      else if (tp[0] == 0)
	np[1] = tp[2], np[0] = tp[1], nn = 2;
      else
	np[2] = tp[2], np[1] = tp[1], np[0] = tp[0], nn = 3;
#else
      if (tp[0] == 0)
	np[0] = tp[1], nn = 1;
      else
	np[1] = tp[1], np[0] = tp[0], nn = 2;
#endif
      dn += nn + 1;
      if (dest->_mp_den._mp_alloc < dn)
	_mpz_realloc (&(dest->_mp_den), dn);
      dp = PTR(&(dest->_mp_den));
      MPN_ZERO (dp, dn - 1);
      dp[dn - 1] = 1;
      count_trailing_zeros (c, np[0] | dp[0]);
      if (c != 0)
	{
	  mpn_rshift (np, np, nn, c);
	  nn -= np[nn - 1] == 0;
	  mpn_rshift (dp, dp, dn, c);
	  dn -= dp[dn - 1] == 0;
	}
      SIZ(&(dest->_mp_den)) = dn;
      SIZ(&(dest->_mp_num)) = negative ? -nn : nn;
    }
  else
    {
      nn = exp;
      if (dest->_mp_num._mp_alloc < nn)
	_mpz_realloc (&(dest->_mp_num), nn);
      np = PTR(&(dest->_mp_num));
#if BITS_PER_MP_LIMB == 32
      switch (nn)
        {
	default:
          MPN_ZERO (np, nn - 3);
          np += nn - 3;
	  /* fall through */
	case 3:
	  np[2] = tp[2], np[1] = tp[1], np[0] = tp[0];
	  break;
	case 2:
	  np[1] = tp[2], np[0] = tp[1];
	  break;
	}
#else
      switch (nn)
        {
	default:
	  MPN_ZERO (np, nn - 2);
	  np += nn - 2;
	  /* fall through */
	case 2:
	  np[1] = tp[1], np[0] = tp[0];
	  break;
	}
#endif
      dp = PTR(&(dest->_mp_den));
      dp[0] = 1;
      SIZ(&(dest->_mp_den)) = 1;
      SIZ(&(dest->_mp_num)) = negative ? -nn : nn;
    }
}
