1  /* mpf_mul -- Multiply two floats.
       2  
       3  Copyright 1993, 1994, 1996, 2001, 2005, 2019, 2020 Free Software
       4  Foundation, Inc.
       5  
       6  This file is part of the GNU MP Library.
       7  
       8  The GNU MP Library is free software; you can redistribute it and/or modify
       9  it under the terms of either:
      10  
      11    * the GNU Lesser General Public License as published by the Free
      12      Software Foundation; either version 3 of the License, or (at your
      13      option) any later version.
      14  
      15  or
      16  
      17    * the GNU General Public License as published by the Free Software
      18      Foundation; either version 2 of the License, or (at your option) any
      19      later version.
      20  
      21  or both in parallel, as here.
      22  
      23  The GNU MP Library is distributed in the hope that it will be useful, but
      24  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      25  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      26  for more details.
      27  
      28  You should have received copies of the GNU General Public License and the
      29  GNU Lesser General Public License along with the GNU MP Library.  If not,
      30  see https://www.gnu.org/licenses/.  */
      31  
      32  #include "gmp-impl.h"
      33  
      34  void
      35  mpf_mul (mpf_ptr r, mpf_srcptr u, mpf_srcptr v)
      36  {
      37    mp_size_t sign_product;
      38    mp_size_t prec = PREC (r);
      39    mp_size_t rsize;
      40    mp_limb_t cy_limb;
      41    mp_ptr rp, tp;
      42    mp_size_t adj;
      43    TMP_DECL;
      44  
      45    if (u == v)
      46      {
      47        mp_srcptr up;
      48        mp_size_t usize;
      49  
      50        sign_product = 0;
      51  
      52        usize = ABSIZ (u);
      53  
      54        up = PTR (u);
      55        if (usize > prec)
      56  	{
      57  	  up += usize - prec;
      58  	  usize = prec;
      59  	}
      60  
      61        if (usize == 0)
      62  	{
      63  	  SIZ (r) = 0;
      64  	  EXP (r) = 0;		/* ??? */
      65  	  return;
      66  	}
      67        else
      68  	{
      69  	  TMP_MARK;
      70  	  rsize = 2 * usize;
      71  	  tp = TMP_ALLOC_LIMBS (rsize);
      72  
      73  	  mpn_sqr (tp, up, usize);
      74  	  cy_limb = tp[rsize - 1];
      75  	}
      76      }
      77    else
      78      {
      79        mp_srcptr up, vp;
      80        mp_size_t usize, vsize;
      81  
      82        usize = SIZ (u);
      83        vsize = SIZ (v);
      84        sign_product = usize ^ vsize;
      85  
      86        usize = ABS (usize);
      87        vsize = ABS (vsize);
      88  
      89        up = PTR (u);
      90        vp = PTR (v);
      91        if (usize > prec)
      92  	{
      93  	  up += usize - prec;
      94  	  usize = prec;
      95  	}
      96        if (vsize > prec)
      97  	{
      98  	  vp += vsize - prec;
      99  	  vsize = prec;
     100  	}
     101  
     102        if (usize == 0 || vsize == 0)
     103  	{
     104  	  SIZ (r) = 0;
     105  	  EXP (r) = 0;
     106  	  return;
     107  	}
     108        else
     109  	{
     110  	  TMP_MARK;
     111  	  rsize = usize + vsize;
     112  	  tp = TMP_ALLOC_LIMBS (rsize);
     113  	  cy_limb = (usize >= vsize
     114  		     ? mpn_mul (tp, up, usize, vp, vsize)
     115  		     : mpn_mul (tp, vp, vsize, up, usize));
     116  
     117  	}
     118      }
     119  
     120    adj = cy_limb == 0;
     121    rsize -= adj;
     122    prec++;
     123    if (rsize > prec)
     124      {
     125        tp += rsize - prec;
     126        rsize = prec;
     127      }
     128    rp = PTR (r);
     129    MPN_COPY (rp, tp, rsize);
     130    EXP (r) = EXP (u) + EXP (v) - adj;
     131    SIZ (r) = sign_product >= 0 ? rsize : -rsize;
     132  
     133    TMP_FREE;
     134  }