source/libs/gmp/gmp-src/mpz/and.c

   1 /* mpz_and -- Logical and.
   2
   3 Copyright 1991, 1993, 1994, 1996, 1997, 2000, 2001, 2003, 2005, 2012 Free
   4 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 "gmp.h"
  33 #include "gmp-impl.h"
  34
  35 void
  36 mpz_and (mpz_ptr res, mpz_srcptr op1, mpz_srcptr op2)
  37 {
  38   mp_srcptr op1_ptr, op2_ptr;
  39   mp_size_t op1_size, op2_size;
  40   mp_ptr res_ptr;
  41   mp_size_t res_size;
  42   mp_size_t i;
  43   TMP_DECL;
  44
  45   TMP_MARK;
  46   op1_size = SIZ(op1);
  47   op2_size = SIZ(op2);
  48
  49   op1_ptr = PTR(op1);
  50   op2_ptr = PTR(op2);
  51
  52   if (op1_size >= 0)
  53     {
  54       if (op2_size >= 0)
  55         {
  56           res_size = MIN (op1_size, op2_size);
  57           /* First loop finds the size of the result.  */
  58           for (i = res_size - 1; i >= 0; i--)
  59             if ((op1_ptr[i] & op2_ptr[i]) != 0)
  60               break;
  61           res_size = i + 1;
  62
  63           /* Handle allocation, now then we know exactly how much space is
  64              needed for the result.  */
  65           res_ptr = MPZ_REALLOC (res, res_size);
  66           /* Don't re-read op1_ptr and op2_ptr.  Since res_size <=
  67              MIN(op1_size, op2_size), res is not changed when op1
  68              is identical to res or op2 is identical to res.  */
  69
  70           SIZ(res) = res_size;
  71           if (LIKELY (res_size != 0))
  72             mpn_and_n (res_ptr, op1_ptr, op2_ptr, res_size);
  73           return;
  74         }
  75       else /* op2_size < 0 */
  76         {
  77           /* Fall through to the code at the end of the function.  */
  78         }
  79     }
  80   else
  81     {
  82       if (op2_size < 0)
  83         {
  84           mp_ptr opx, opy;
  85           mp_limb_t cy;
  86
  87           /* Both operands are negative, so will be the result.
  88              -((-OP1) & (-OP2)) = -(~(OP1 - 1) & ~(OP2 - 1)) =
  89              = ~(~(OP1 - 1) & ~(OP2 - 1)) + 1 =
  90              = ((OP1 - 1) | (OP2 - 1)) + 1      */
  91
  92           /* It might seem as we could end up with an (invalid) result with
  93              a leading zero-limb here when one of the operands is of the
  94              type 1,,0,,..,,.0.  But some analysis shows that we surely
  95              would get carry into the zero-limb in this situation...  */
  96
  97           op1_size = -op1_size;
  98           op2_size = -op2_size;
  99
 100           if (op1_size > op2_size)
 101             MPN_SRCPTR_SWAP (op1_ptr, op1_size, op2_ptr, op2_size);
 102
 103           TMP_ALLOC_LIMBS_2 (opx, op1_size, opy, op2_size);
 104           mpn_sub_1 (opx, op1_ptr, op1_size, (mp_limb_t) 1);
 105           op1_ptr = opx;
 106
 107           mpn_sub_1 (opy, op2_ptr, op2_size, (mp_limb_t) 1);
 108           op2_ptr = opy;
 109
 110           res_ptr = MPZ_REALLOC (res, 1 + op2_size);
 111           /* Don't re-read OP1_PTR and OP2_PTR.  They point to temporary
 112              space--never to the space PTR(res) used to point to before
 113              reallocation.  */
 114
 115           MPN_COPY (res_ptr + op1_size, op2_ptr + op1_size,
 116                     op2_size - op1_size);
 117           mpn_ior_n (res_ptr, op1_ptr, op2_ptr, op1_size);
 118           res_size = op2_size;
 119
 120           cy = mpn_add_1 (res_ptr, res_ptr, res_size, (mp_limb_t) 1);
 121           res_ptr[res_size] = cy;
 122           res_size += (cy != 0);
 123
 124           SIZ(res) = -res_size;
 125           TMP_FREE;
 126           return;
 127         }
 128       else
 129         {
 130           /* We should compute -OP1 & OP2.  Swap OP1 and OP2 and fall
 131              through to the code that handles OP1 & -OP2.  */
 132           MPN_SRCPTR_SWAP (op1_ptr, op1_size, op2_ptr, op2_size);
 133         }
 134
 135     }
 136
 137   {
 138 #if ANDNEW
 139     mp_size_t op2_lim;
 140     mp_size_t count;
 141
 142     /* OP2 must be negated as with infinite precision.
 143
 144        Scan from the low end for a non-zero limb.  The first non-zero
 145        limb is simply negated (two's complement).  Any subsequent
 146        limbs are one's complemented.  Of course, we don't need to
 147        handle more limbs than there are limbs in the other, positive
 148        operand as the result for those limbs is going to become zero
 149        anyway.  */
 150
 151     /* Scan for the least significant non-zero OP2 limb, and zero the
 152        result meanwhile for those limb positions.  (We will surely
 153        find a non-zero limb, so we can write the loop with one
 154        termination condition only.)  */
 155     for (i = 0; op2_ptr[i] == 0; i++)
 156       res_ptr[i] = 0;
 157     op2_lim = i;
 158
 159     op2_size = -op2_size;
 160
 161     if (op1_size <= op2_size)
 162       {
 163         /* The ones-extended OP2 is >= than the zero-extended OP1.
 164            RES_SIZE <= OP1_SIZE.  Find the exact size.  */
 165         for (i = op1_size - 1; i > op2_lim; i--)
 166           if ((op1_ptr[i] & ~op2_ptr[i]) != 0)
 167             break;
 168         res_size = i + 1;
 169         for (i = res_size - 1; i > op2_lim; i--)
 170           res_ptr[i] = op1_ptr[i] & ~op2_ptr[i];
 171         res_ptr[op2_lim] = op1_ptr[op2_lim] & -op2_ptr[op2_lim];
 172         /* Yes, this *can* happen!  */
 173         MPN_NORMALIZE (res_ptr, res_size);
 174       }
 175     else
 176       {
 177         /* The ones-extended OP2 is < than the zero-extended OP1.
 178            RES_SIZE == OP1_SIZE, since OP1 is normalized.  */
 179         res_size = op1_size;
 180         MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, op1_size - op2_size);
 181         for (i = op2_size - 1; i > op2_lim; i--)
 182           res_ptr[i] = op1_ptr[i] & ~op2_ptr[i];
 183         res_ptr[op2_lim] = op1_ptr[op2_lim] & -op2_ptr[op2_lim];
 184       }
 185
 186     SIZ(res) = res_size;
 187 #else
 188
 189     /* OP1 is positive and zero-extended,
 190        OP2 is negative and ones-extended.
 191        The result will be positive.
 192        OP1 & -OP2 = OP1 & ~(OP2 - 1).  */
 193
 194     mp_ptr opx;
 195
 196     op2_size = -op2_size;
 197     opx = TMP_ALLOC_LIMBS (op2_size);
 198     mpn_sub_1 (opx, op2_ptr, op2_size, (mp_limb_t) 1);
 199     op2_ptr = opx;
 200
 201     if (op1_size > op2_size)
 202       {
 203         /* The result has the same size as OP1, since OP1 is normalized
 204            and longer than the ones-extended OP2.  */
 205         res_size = op1_size;
 206
 207         /* Handle allocation, now then we know exactly how much space is
 208            needed for the result.  */
 209         res_ptr = MPZ_REALLOC (res, res_size);
 210         /* Don't re-read OP1_PTR or OP2_PTR.  Since res_size = op1_size,
 211            op1 is not changed if it is identical to res.
 212            OP2_PTR points to temporary space.  */
 213
 214         MPN_COPY (res_ptr + op2_size, op1_ptr + op2_size, res_size - op2_size);
 215         mpn_andn_n (res_ptr, op1_ptr, op2_ptr, op2_size);
 216
 217         SIZ(res) = res_size;
 218       }
 219     else
 220       {
 221         /* Find out the exact result size.  Ignore the high limbs of OP2,
 222            OP1 is zero-extended and would make the result zero.  */
 223         for (i = op1_size - 1; i >= 0; i--)
 224           if ((op1_ptr[i] & ~op2_ptr[i]) != 0)
 225             break;
 226         res_size = i + 1;
 227
 228         /* Handle allocation, now then we know exactly how much space is
 229            needed for the result.  */
 230         res_ptr = MPZ_REALLOC (res, res_size);
 231         /* Don't re-read OP1_PTR.  Since res_size <= op1_size,
 232            op1 is not changed if it is identical to res.
 233            Don't re-read OP2_PTR.  It points to temporary space--never
 234            to the space PTR(res) used to point to before reallocation.  */
 235
 236         if (LIKELY (res_size != 0))
 237           mpn_andn_n (res_ptr, op1_ptr, op2_ptr, res_size);
 238
 239         SIZ(res) = res_size;
 240       }
 241 #endif
 242   }
 243   TMP_FREE;
 244 }