135 lines
3.3 KiB
C
135 lines
3.3 KiB
C
/* mpz_add, mpz_sub -- add or subtract integers.
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Copyright 1991, 1993, 1994, 1996, 2000, 2001 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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#ifdef BERKELEY_MP
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#include "mp.h"
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#ifdef OPERATION_add
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#define FUNCTION madd
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#define VARIATION
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#endif
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#ifdef OPERATION_sub
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#define FUNCTION msub
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#define VARIATION -
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#endif
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#define ARGUMENTS mpz_srcptr u, mpz_srcptr v, mpz_ptr w
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#else /* normal GMP */
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#ifdef OPERATION_add
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#define FUNCTION mpz_add
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#define VARIATION
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#endif
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#ifdef OPERATION_sub
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#define FUNCTION mpz_sub
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#define VARIATION -
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#endif
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#define ARGUMENTS mpz_ptr w, mpz_srcptr u, mpz_srcptr v
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#endif
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#ifndef FUNCTION
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Error, need OPERATION_add or OPERATION_sub
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#endif
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void
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FUNCTION (ARGUMENTS)
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{
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mp_srcptr up, vp;
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mp_ptr wp;
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mp_size_t usize, vsize, wsize;
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mp_size_t abs_usize;
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mp_size_t abs_vsize;
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usize = u->_mp_size;
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vsize = VARIATION v->_mp_size;
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abs_usize = ABS (usize);
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abs_vsize = ABS (vsize);
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if (abs_usize < abs_vsize)
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{
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/* Swap U and V. */
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MPZ_SRCPTR_SWAP (u, v);
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MP_SIZE_T_SWAP (usize, vsize);
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MP_SIZE_T_SWAP (abs_usize, abs_vsize);
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}
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/* True: ABS_USIZE >= ABS_VSIZE. */
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/* If not space for w (and possible carry), increase space. */
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wsize = abs_usize + 1;
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if (w->_mp_alloc < wsize)
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_mpz_realloc (w, wsize);
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/* These must be after realloc (u or v may be the same as w). */
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up = u->_mp_d;
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vp = v->_mp_d;
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wp = w->_mp_d;
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if ((usize ^ vsize) < 0)
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{
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/* U and V have different sign. Need to compare them to determine
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which operand to subtract from which. */
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/* This test is right since ABS_USIZE >= ABS_VSIZE. */
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if (abs_usize != abs_vsize)
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{
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mpn_sub (wp, up, abs_usize, vp, abs_vsize);
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wsize = abs_usize;
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MPN_NORMALIZE (wp, wsize);
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if (usize < 0)
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wsize = -wsize;
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}
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else if (mpn_cmp (up, vp, abs_usize) < 0)
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{
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mpn_sub_n (wp, vp, up, abs_usize);
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wsize = abs_usize;
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MPN_NORMALIZE (wp, wsize);
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if (usize >= 0)
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wsize = -wsize;
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}
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else
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{
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mpn_sub_n (wp, up, vp, abs_usize);
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wsize = abs_usize;
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MPN_NORMALIZE (wp, wsize);
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if (usize < 0)
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wsize = -wsize;
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}
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}
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else
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{
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/* U and V have same sign. Add them. */
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mp_limb_t cy_limb = mpn_add (wp, up, abs_usize, vp, abs_vsize);
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wp[abs_usize] = cy_limb;
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wsize = abs_usize + cy_limb;
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if (usize < 0)
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wsize = -wsize;
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}
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w->_mp_size = wsize;
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}
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