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+/* 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;
+ }
+ }
+}
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