/* mpfr_set_ui -- set a MPFR number from a machine unsigned integer

Copyright (C) 1999-2001 Free Software Foundation.

This file is part of the MPFR Library.

The MPFR 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 MPFR 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 MPFR 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"
#include "mpfr.h"
#include "mpfr-impl.h"

int
mpfr_set_ui (mpfr_ptr x, unsigned long i, mp_rnd_t rnd_mode)
{
  int inex = 0;

  MPFR_CLEAR_FLAGS(x);
  if (i == 0)
    MPFR_SET_ZERO(x);  /* the sign will be set later */
  else
    {
      mp_size_t xn;
      unsigned int cnt, nbits;
      mp_limb_t *xp;

      xn = (MPFR_PREC(x)-1)/BITS_PER_MP_LIMB;
      count_leading_zeros(cnt, (mp_limb_t) i);

      xp = MPFR_MANT(x);
      xp[xn] = ((mp_limb_t) i) << cnt;
      /* don't forget to put zero in lower limbs */
      MPN_ZERO(xp, xn);

      MPFR_EXP(x) = nbits = BITS_PER_MP_LIMB - cnt;
      inex = mpfr_check_range(x, rnd_mode);
      if (inex)
        return inex; /* underflow or overflow */

      /* round if MPFR_PREC(x) smaller than length of i */
      if (MPFR_PREC(x) < nbits)
        {
          int carry;
          carry = mpfr_round_raw(xp+xn, xp+xn, nbits, 0, MPFR_PREC(x),
                                 rnd_mode, &inex);
          if (carry)
            {
              mp_exp_t exp = MPFR_EXP(x);

              if (exp == __mpfr_emax)
                return mpfr_set_overflow(x, rnd_mode, 1);

              MPFR_EXP(x)++;
              xp[xn] = MP_LIMB_T_HIGHBIT;
            }
        }
    }

  /* warning: don't change the precision of x! */
  if (MPFR_SIGN(x) < 0)
    MPFR_CHANGE_SIGN(x);

  MPFR_RET(inex);
}