mul.c
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上传日期:2022-08-06
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- /* mpz_mul -- Multiply two integers.
- Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2005, 2009 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 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.
- 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 Lesser General Public
- License for more details.
- You should have received a copy of the GNU Lesser General Public License
- along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
- #include <stdio.h> /* for NULL */
- #include "gmp.h"
- #include "gmp-impl.h"
- #ifdef BERKELEY_MP
- #include "mp.h"
- #endif
- void
- #ifndef BERKELEY_MP
- mpz_mul (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
- #else /* BERKELEY_MP */
- mult (mpz_srcptr u, mpz_srcptr v, mpz_ptr w)
- #endif /* BERKELEY_MP */
- {
- mp_size_t usize = SIZ(u);
- mp_size_t vsize = SIZ(v);
- 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;
- 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)
- {
- MPZ_REALLOC (w, usize+vsize);
- wp = PTR(w);
- 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)
- {
- MPZ_REALLOC (w, usize+1);
- wp = PTR(w);
- 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 (wp == up || wp == vp)
- {
- free_me = wp;
- free_me_size = ALLOC(w);
- }
- else
- (*__gmp_free_func) (wp, ALLOC(w) * BYTES_PER_MP_LIMB);
- ALLOC(w) = wsize;
- wp = (mp_ptr) (*__gmp_allocate_func) (wsize * BYTES_PER_MP_LIMB);
- 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);
- wsize = usize + vsize;
- cy_limb = wp[wsize - 1];
- }
- else
- {
- cy_limb = mpn_mul (wp, up, usize, vp, vsize);
- wsize = usize + vsize;
- }
- wsize -= cy_limb == 0;
- SIZ(w) = sign_product < 0 ? -wsize : wsize;
- if (free_me != NULL)
- (*__gmp_free_func) (free_me, free_me_size * BYTES_PER_MP_LIMB);
- TMP_FREE;
- }