/* Reference floating point routines.

Copyright (C) 1996 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"

#if __STDC__
void ref_mpf_add (mpf_t, const mpf_t, const mpf_t);
void ref_mpf_sub (mpf_t, const mpf_t, const mpf_t);
#else
void ref_mpf_add ();
void ref_mpf_sub ();
#endif

void
#if __STDC__
ref_mpf_add (mpf_t w, const mpf_t u, const mpf_t v)
#else
ref_mpf_add (w, u, v)
     mpf_t w;
     const mpf_t u;
     const mpf_t v;
#endif
{
  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 * 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 * 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);
      ref_mpf_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
#if __STDC__
ref_mpf_sub (mpf_t w, const mpf_t u, const mpf_t v)
#else
ref_mpf_sub (w, u, v)
     mpf_t w;
     const mpf_t u;
     const mpf_t v;
#endif
{
  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 * 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 * 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);
      ref_mpf_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);
}
