/* mpz_and -- Logical and.

Copyright 1991, 1993, 1994, 1996, 1997, 2000, 2001, 2003, 2005, 2012,

2015-2018 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 "gmp-impl.h"

void

mpz_and (mpz_ptr res, mpz_srcptr op1, mpz_srcptr op2)

{

  mp_srcptr op1_ptr, op2_ptr;

  mp_size_t op1_size, op2_size;

  mp_ptr res_ptr;

  mp_size_t res_size;

  mp_size_t i;

  op1_size = SIZ(op1);

  op2_size = SIZ(op2);

  if (op1_size < op2_size)

    {

      MPZ_SRCPTR_SWAP (op1, op2);

      MP_SIZE_T_SWAP (op1_size, op2_size);

    }

  op1_ptr = PTR(op1);

  op2_ptr = PTR(op2);

  if (op2_size >= 0)

    {

      /* First loop finds the size of the result.  */

      for (i = op2_size; --i >= 0;)

  if ((op1_ptr[i] & op2_ptr[i]) != 0)

    {

      res_size = i + 1;

      /* Handle allocation, now then we know exactly how much space is

         needed for the result.  */

      /* Don't re-read op1_ptr and op2_ptr.  Since res_size <=

         MIN(op1_size, op2_size), res is not changed when op1

         is identical to res or op2 is identical to res.  */

      SIZ (res) = res_size;

      mpn_and_n (MPZ_NEWALLOC (res, res_size), op1_ptr, op2_ptr, res_size);

      return;

    }

      SIZ (res) = 0;

    }

  else

    {

      TMP_DECL;

      op2_size = -op2_size;

      TMP_MARK;

      if (op1_size < 0)

  {

    mp_ptr opx, opy;

    /* Both operands are negative, so will be the result.

       -((-OP1) & (-OP2)) = -(~(OP1 - 1) & ~(OP2 - 1)) =

       = ~(~(OP1 - 1) & ~(OP2 - 1)) + 1 =

       = ((OP1 - 1) | (OP2 - 1)) + 1      */

    /* It might seem as we could end up with an (invalid) result with

       a leading zero-limb here when one of the operands is of the

       type 1,,0,,..,,.0.  But some analysis shows that we surely

       would get carry into the zero-limb in this situation...  */

    op1_size = -op1_size;

    TMP_ALLOC_LIMBS_2 (opx, op1_size, opy, op2_size);

    mpn_sub_1 (opx, op1_ptr, op1_size, (mp_limb_t) 1);

    op1_ptr = opx;

    mpn_sub_1 (opy, op2_ptr, op2_size, (mp_limb_t) 1);

    op2_ptr = opy;

    res_ptr = MPZ_NEWALLOC (res, 1 + op2_size);

    /* Don't re-read OP1_PTR and OP2_PTR.  They point to temporary

       space--never to the space PTR(res) used to point to before

       reallocation.  */

    MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size,

        op2_size - op1_size);

    mpn_ior_n (res_ptr, op1_ptr, op2_ptr, op1_size);

    TMP_FREE;

    res_size = op2_size;

    res_ptr[res_size] = 0;

    MPN_INCR_U (res_ptr, res_size + 1, (mp_limb_t) 1);

    res_size += res_ptr[res_size];

    SIZ(res) = -res_size;

  }

      else

  {

#if ANDNEW

    mp_size_t op2_lim;

    mp_size_t count;

    /* OP2 must be negated as with infinite precision.

       Scan from the low end for a non-zero limb.  The first non-zero

       limb is simply negated (two's complement).  Any subsequent

       limbs are one's complemented.  Of course, we don't need to

       handle more limbs than there are limbs in the other, positive

       operand as the result for those limbs is going to become zero

       anyway.  */

    /* Scan for the least significant non-zero OP2 limb, and zero the

       result meanwhile for those limb positions.  (We will surely

       find a non-zero limb, so we can write the loop with one

       termination condition only.)  */

    for (i = 0; op2_ptr[i] == 0; i++)

      res_ptr[i] = 0;

    op2_lim = i;

    if (op1_size <= op2_size)

      {

        /* The ones-extended OP2 is >= than the zero-extended OP1.

     RES_SIZE <= OP1_SIZE.  Find the exact size.  */

        for (i = op1_size - 1; i > op2_lim; i--)

    if ((op1_ptr[i] & ~op2_ptr[i]) != 0)

      break;

        res_size = i + 1;

        for (i = res_size - 1; i > op2_lim; i--)

    res_ptr[i] = op1_ptr[i] & ~op2_ptr[i];

        res_ptr[op2_lim] = op1_ptr[op2_lim] & -op2_ptr[op2_lim];

        /* Yes, this *can* happen!  */

        MPN_NORMALIZE (res_ptr, res_size);

      }

    else

      {

        /* The ones-extended OP2 is < than the zero-extended OP1.

     RES_SIZE == OP1_SIZE, since OP1 is normalized.  */

        res_size = op1_size;

        MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, op1_size - op2_size);

        for (i = op2_size - 1; i > op2_lim; i--)

    res_ptr[i] = op1_ptr[i] & ~op2_ptr[i];

        res_ptr[op2_lim] = op1_ptr[op2_lim] & -op2_ptr[op2_lim];

      }

#else

    /* OP1 is positive and zero-extended,

       OP2 is negative and ones-extended.

       The result will be positive.

       OP1 & -OP2 = OP1 & ~(OP2 - 1).  */

    mp_ptr opx;

    opx = TMP_ALLOC_LIMBS (op2_size);

    mpn_sub_1 (opx, op2_ptr, op2_size, (mp_limb_t) 1);

    op2_ptr = opx;

    if (op1_size > op2_size)

      {

        /* The result has the same size as OP1, since OP1 is normalized

     and longer than the ones-extended OP2.  */

        res_size = op1_size;

        /* Handle allocation, now then we know exactly how much space is

     needed for the result.  */

        res_ptr = MPZ_NEWALLOC (res, res_size);

        /* Don't re-read OP1_PTR or OP2_PTR.  Since res_size = op1_size,

     op1 is not changed if it is identical to res.

     OP2_PTR points to temporary space.  */

        mpn_andn_n (res_ptr, op1_ptr, op2_ptr, op2_size);

        MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, res_size - op2_size);

      }

    else

      {

        /* Find out the exact result size.  Ignore the high limbs of OP2,

     OP1 is zero-extended and would make the result zero.  */

        res_size = 0;

        for (i = op1_size; --i >= 0;)

    if ((op1_ptr[i] & ~op2_ptr[i]) != 0)

      {

        res_size = i + 1;

        /* Handle allocation, now then we know exactly how much

           space is needed for the result.  */

        /* Don't re-read OP1_PTR.  Since res_size <= op1_size,

           op1 is not changed if it is identical to res.  Don't

           re-read OP2_PTR.  It points to temporary space--never

           to the space PTR(res) used to point to before

           reallocation.  */

        mpn_andn_n (MPZ_NEWALLOC (res, res_size), op1_ptr, op2_ptr, res_size);

        break;

      }

      }

#endif

    SIZ(res) = res_size;

    TMP_FREE;

  }

    }

}