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mul.c revision 1.1.1.4 
      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 	if (wp == up || wp == vp)
    108 	  {
    109 	    free_me = wp;
    110 	    free_me_size = ALLOC (w);
    111 	  }
    112 	else
    113 	  (*__gmp_free_func) (wp, (size_t) ALLOC (w) * GMP_LIMB_BYTES);
    114 
    115       ALLOC (w) = wsize;
    116       wp = __GMP_ALLOCATE_FUNC_LIMBS (wsize);
    117       PTR (w) = wp;
    118     }
    119   else
    120     {
    121       /* Make U and V not overlap with W.  */
    122       if (wp == up)
    123 	{
    124 	  /* W and U are identical.  Allocate temporary space for U.  */
    125 	  up = TMP_ALLOC_LIMBS (usize);
    126 	  /* Is V identical too?  Keep it identical with U.  */
    127 	  if (wp == vp)
    128 	    vp = up;
    129 	  /* Copy to the temporary space.  */
    130 	  MPN_COPY (up, wp, usize);
    131 	}
    132       else if (wp == vp)
    133 	{
    134 	  /* W and V are identical.  Allocate temporary space for V.  */
    135 	  vp = TMP_ALLOC_LIMBS (vsize);
    136 	  /* Copy to the temporary space.  */
    137 	  MPN_COPY (vp, wp, vsize);
    138 	}
    139     }
    140 
    141   if (up == vp)
    142     {
    143       mpn_sqr (wp, up, usize);
    144       cy_limb = wp[wsize - 1];
    145     }
    146   else
    147     {
    148       cy_limb = mpn_mul (wp, up, usize, vp, vsize);
    149     }
    150 
    151   wsize -= cy_limb == 0;
    152 
    153   SIZ (w) = sign_product < 0 ? -wsize : wsize;
    154   if (free_me != NULL)
    155     (*__gmp_free_func) (free_me, free_me_size * GMP_LIMB_BYTES);
    156   TMP_FREE;
    157 }
    158