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mul.c revision 1.1.1.5 
      1 /* mpz_mul -- Multiply two integers.
      2 
      3 Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2005, 2009, 2011, 2012,
      4 2015 Free Software 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 <stdio.h> /* for NULL */
     33 #include "gmp-impl.h"
     34 
     35 
     36 void
     37 mpz_mul (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
     38 {
     39   mp_size_t usize;
     40   mp_size_t vsize;
     41   mp_size_t wsize;
     42   mp_size_t sign_product;
     43   mp_ptr up, vp;
     44   mp_ptr wp;
     45   mp_ptr free_me;
     46   size_t free_me_size;
     47   mp_limb_t cy_limb;
     48   TMP_DECL;
     49 
     50   usize = SIZ (u);
     51   vsize = SIZ (v);
     52   sign_product = usize ^ vsize;
     53   usize = ABS (usize);
     54   vsize = ABS (vsize);
     55 
     56   if (usize < vsize)
     57     {
     58       MPZ_SRCPTR_SWAP (u, v);
     59       MP_SIZE_T_SWAP (usize, vsize);
     60     }
     61 
     62   if (vsize == 0)
     63     {
     64       SIZ (w) = 0;
     65       return;
     66     }
     67 
     68 #if HAVE_NATIVE_mpn_mul_2
     69   if (vsize <= 2)
     70     {
     71       wp = MPZ_REALLOC (w, usize+vsize);
     72       if (vsize == 1)
     73 	cy_limb = mpn_mul_1 (wp, PTR (u), usize, PTR (v)[0]);
     74       else
     75 	{
     76 	  cy_limb = mpn_mul_2 (wp, PTR (u), usize, PTR (v));
     77 	  usize++;
     78 	}
     79       wp[usize] = cy_limb;
     80       usize += (cy_limb != 0);
     81       SIZ (w) = (sign_product >= 0 ? usize : -usize);
     82       return;
     83     }
     84 #else
     85   if (vsize == 1)
     86     {
     87       wp = MPZ_REALLOC (w, usize+1);
     88       cy_limb = mpn_mul_1 (wp, PTR (u), usize, PTR (v)[0]);
     89       wp[usize] = cy_limb;
     90       usize += (cy_limb != 0);
     91       SIZ (w) = (sign_product >= 0 ? usize : -usize);
     92       return;
     93     }
     94 #endif
     95 
     96   TMP_MARK;
     97   free_me = NULL;
     98   up = PTR (u);
     99   vp = PTR (v);
    100   wp = PTR (w);
    101 
    102   /* Ensure W has space enough to store the result.  */
    103   wsize = usize + vsize;
    104   if (ALLOC (w) < wsize)
    105     {
    106       if (ALLOC (w) != 0)
    107 	{
    108 	  if (wp == up || wp == vp)
    109 	    {
    110 	      free_me = wp;
    111 	      free_me_size = ALLOC (w);
    112 	    }
    113 	  else
    114 	    (*__gmp_free_func) (wp, (size_t) ALLOC (w) * GMP_LIMB_BYTES);
    115 	}
    116 
    117       ALLOC (w) = wsize;
    118       wp = __GMP_ALLOCATE_FUNC_LIMBS (wsize);
    119       PTR (w) = wp;
    120     }
    121   else
    122     {
    123       /* Make U and V not overlap with W.  */
    124       if (wp == up)
    125 	{
    126 	  /* W and U are identical.  Allocate temporary space for U.  */
    127 	  up = TMP_ALLOC_LIMBS (usize);
    128 	  /* Is V identical too?  Keep it identical with U.  */
    129 	  if (wp == vp)
    130 	    vp = up;
    131 	  /* Copy to the temporary space.  */
    132 	  MPN_COPY (up, wp, usize);
    133 	}
    134       else if (wp == vp)
    135 	{
    136 	  /* W and V are identical.  Allocate temporary space for V.  */
    137 	  vp = TMP_ALLOC_LIMBS (vsize);
    138 	  /* Copy to the temporary space.  */
    139 	  MPN_COPY (vp, wp, vsize);
    140 	}
    141     }
    142 
    143   if (up == vp)
    144     {
    145       mpn_sqr (wp, up, usize);
    146       cy_limb = wp[wsize - 1];
    147     }
    148   else
    149     {
    150       cy_limb = mpn_mul (wp, up, usize, vp, vsize);
    151     }
    152 
    153   wsize -= cy_limb == 0;
    154 
    155   SIZ (w) = sign_product < 0 ? -wsize : wsize;
    156   if (free_me != NULL)
    157     (*__gmp_free_func) (free_me, free_me_size * GMP_LIMB_BYTES);
    158   TMP_FREE;
    159 }
    160