/* Reference floating point routines.

Copyright 1996, 2001 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 "tests.h"


void
refmpf_add (mpf_ptr w, mpf_srcptr u, mpf_srcptr v)
{
  mp_size_t hi, lo, size;
  mp_ptr ut, vt, wt;
  int neg;
  mp_exp_t exp;
  mp_limb_t cy;
  TMP_DECL (mark);

  TMP_MARK (mark);

  if (SIZ (u) == 0)
    {
      size = ABSIZ (v);
      wt = (mp_ptr) TMP_ALLOC ((size+1) * BYTES_PER_MP_LIMB);
      MPN_COPY (wt, PTR (v), size);
      exp = EXP (v);
      neg = SIZ (v) < 0;
      goto done;
    }
  if (SIZ (v) == 0)
    {
      size = ABSIZ (u);
      wt = (mp_ptr) TMP_ALLOC ((size+1) * BYTES_PER_MP_LIMB);
      MPN_COPY (wt, PTR (u), size);
      exp = EXP (u);
      neg = SIZ (u) < 0;
      goto done;
    }
  if ((SIZ (u) ^ SIZ (v)) < 0)
    {
      mpf_t tmp;
      SIZ (tmp) = -SIZ (v);
      EXP (tmp) = EXP (v);
      PTR (tmp) = PTR (v);
      refmpf_sub (w, u, tmp);
      return;
    }
  neg = SIZ (u) < 0;

  /* Compute the significance of the hi and lo end of the result.  */
  hi = MAX (EXP (u), EXP (v));
  lo = MIN (EXP (u) - ABSIZ (u), EXP (v) - ABSIZ (v));
  size = hi - lo;
  ut = (mp_ptr) TMP_ALLOC ((size + 1) * BYTES_PER_MP_LIMB);
  vt = (mp_ptr) TMP_ALLOC ((size + 1) * BYTES_PER_MP_LIMB);
  wt = (mp_ptr) TMP_ALLOC ((size + 1) * BYTES_PER_MP_LIMB);
  MPN_ZERO (ut, size);
  MPN_ZERO (vt, size);
  {int off;
  off = size + (EXP (u) - hi) - ABSIZ (u);
  MPN_COPY (ut + off, PTR (u), ABSIZ (u));
  off = size + (EXP (v) - hi) - ABSIZ (v);
  MPN_COPY (vt + off, PTR (v), ABSIZ (v));
  }

  cy = mpn_add_n (wt, ut, vt, size);
  wt[size] = cy;
  size += cy;
  exp = hi + cy;

done:
  if (size > PREC (w))
    {
      wt += size - PREC (w);
      size = PREC (w);
    }
  MPN_COPY (PTR (w), wt, size);
  SIZ (w) = neg == 0 ? size : -size;
  EXP (w) = exp;
  TMP_FREE (mark);
}

void
refmpf_sub (mpf_ptr w, mpf_srcptr u, mpf_srcptr v)
{
  mp_size_t hi, lo, size;
  mp_ptr ut, vt, wt;
  int neg;
  mp_exp_t exp;
  TMP_DECL (mark);

  TMP_MARK (mark);

  if (SIZ (u) == 0)
    {
      size = ABSIZ (v);
      wt = (mp_ptr) TMP_ALLOC ((size+1) * BYTES_PER_MP_LIMB);
      MPN_COPY (wt, PTR (v), size);
      exp = EXP (v);
      neg = SIZ (v) > 0;
      goto done;
    }
  if (SIZ (v) == 0)
    {
      size = ABSIZ (u);
      wt = (mp_ptr) TMP_ALLOC ((size+1) * BYTES_PER_MP_LIMB);
      MPN_COPY (wt, PTR (u), size);
      exp = EXP (u);
      neg = SIZ (u) < 0;
      goto done;
    }
  if ((SIZ (u) ^ SIZ (v)) < 0)
    {
      mpf_t tmp;
      SIZ (tmp) = -SIZ (v);
      EXP (tmp) = EXP (v);
      PTR (tmp) = PTR (v);
      refmpf_add (w, u, tmp);
      if (SIZ (u) < 0)
	mpf_neg (w, w);
      return;
    }
  neg = SIZ (u) < 0;

  /* Compute the significance of the hi and lo end of the result.  */
  hi = MAX (EXP (u), EXP (v));
  lo = MIN (EXP (u) - ABSIZ (u), EXP (v) - ABSIZ (v));
  size = hi - lo;
  ut = (mp_ptr) TMP_ALLOC ((size + 1) * BYTES_PER_MP_LIMB);
  vt = (mp_ptr) TMP_ALLOC ((size + 1) * BYTES_PER_MP_LIMB);
  wt = (mp_ptr) TMP_ALLOC ((size + 1) * BYTES_PER_MP_LIMB);
  MPN_ZERO (ut, size);
  MPN_ZERO (vt, size);
  {int off;
  off = size + (EXP (u) - hi) - ABSIZ (u);
  MPN_COPY (ut + off, PTR (u), ABSIZ (u));
  off = size + (EXP (v) - hi) - ABSIZ (v);
  MPN_COPY (vt + off, PTR (v), ABSIZ (v));
  }

  if (mpn_cmp (ut, vt, size) >= 0)
    mpn_sub_n (wt, ut, vt, size);
  else
    {
      mpn_sub_n (wt, vt, ut, size);
      neg ^= 1;
    }
  exp = hi;
  while (size != 0 && wt[size - 1] == 0)
    {
      size--;
      exp--;
    }

done:
  if (size > PREC (w))
    {
      wt += size - PREC (w);
      size = PREC (w);
    }
  MPN_COPY (PTR (w), wt, size);
  SIZ (w) = neg == 0 ? size : -size;
  EXP (w) = exp;
  TMP_FREE (mark);
}
