/* mpz_mul -- Multiply two integers.

Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2005, 2009, 2011, 2012,

2015 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 either:

  * the GNU Lesser General Public License as published by the Free

    Software Foundation; either version 3 of the License, or (at your

    option) any later version.

or

  * the GNU General Public License as published by the Free Software

    Foundation; either version 2 of the License, or (at your option) any

    later version.

or both in parallel, as here.

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 General Public License

for more details.

You should have received copies of the GNU General Public License and the

GNU Lesser General Public License along with the GNU MP Library.  If not,

see https://www.gnu.org/licenses/.  */

#include <stdio.h> /* for NULL */

#include "gmp-impl.h"

void

mpz_mul (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)

{

  mp_size_t usize;

  mp_size_t vsize;

  mp_size_t wsize;

  mp_size_t sign_product;

  mp_ptr up, vp;

  mp_ptr wp;

  mp_ptr free_me;

  size_t free_me_size;

  mp_limb_t cy_limb;

  TMP_DECL;

  usize = SIZ (u);

  vsize = SIZ (v);

  sign_product = usize ^ vsize;

  usize = ABS (usize);

  vsize = ABS (vsize);

  if (usize < vsize)

    {

      MPZ_SRCPTR_SWAP (u, v);

      MP_SIZE_T_SWAP (usize, vsize);

    }

  if (vsize == 0)

    {

      SIZ (w) = 0;

      return;

    }

#if HAVE_NATIVE_mpn_mul_2

  if (vsize <= 2)

    {

      wp = MPZ_REALLOC (w, usize+vsize);

      if (vsize == 1)

  cy_limb = mpn_mul_1 (wp, PTR (u), usize, PTR (v)[0]);

      else

  {

    cy_limb = mpn_mul_2 (wp, PTR (u), usize, PTR (v));

    usize++;

  }

      wp[usize] = cy_limb;

      usize += (cy_limb != 0);

      SIZ (w) = (sign_product >= 0 ? usize : -usize);

      return;

    }

#else

  if (vsize == 1)

    {

      wp = MPZ_REALLOC (w, usize+1);

      cy_limb = mpn_mul_1 (wp, PTR (u), usize, PTR (v)[0]);

      wp[usize] = cy_limb;

      usize += (cy_limb != 0);

      SIZ (w) = (sign_product >= 0 ? usize : -usize);

      return;

    }

#endif

  TMP_MARK;

  free_me = NULL;

  up = PTR (u);

  vp = PTR (v);

  wp = PTR (w);

  /* Ensure W has space enough to store the result.  */

  wsize = usize + vsize;

  if (ALLOC (w) < wsize)

    {

      if (ALLOC (w) != 0)

  {

    if (wp == up || wp == vp)

      {

        free_me = wp;

        free_me_size = ALLOC (w);

      }

    else

      (*__gmp_free_func) (wp, (size_t) ALLOC (w) * GMP_LIMB_BYTES);

  }

      ALLOC (w) = wsize;

      wp = __GMP_ALLOCATE_FUNC_LIMBS (wsize);

      PTR (w) = wp;

    }

  else

    {

      /* Make U and V not overlap with W.  */

      if (wp == up)

  {

    /* W and U are identical.  Allocate temporary space for U.  */

    up = TMP_ALLOC_LIMBS (usize);

    /* Is V identical too?  Keep it identical with U.  */

    if (wp == vp)

      vp = up;

    /* Copy to the temporary space.  */

    MPN_COPY (up, wp, usize);

  }

      else if (wp == vp)

  {

    /* W and V are identical.  Allocate temporary space for V.  */

    vp = TMP_ALLOC_LIMBS (vsize);

    /* Copy to the temporary space.  */

    MPN_COPY (vp, wp, vsize);

  }

    }

  if (up == vp)

    {

      mpn_sqr (wp, up, usize);

      cy_limb = wp[wsize - 1];

    }

  else

    {

      cy_limb = mpn_mul (wp, up, usize, vp, vsize);

    }

  wsize -= cy_limb == 0;

  SIZ (w) = sign_product < 0 ? -wsize : wsize;

  if (free_me != NULL)

    (*__gmp_free_func) (free_me, free_me_size * GMP_LIMB_BYTES);

  TMP_FREE;

}