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/* mpz_add, mpz_sub -- add or subtract integers.
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Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2011, 2012 Free Software
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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 either:
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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or
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* the GNU General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any
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later version.
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or both in parallel, as here.
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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 General Public License
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for more details.
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You should have received copies of the GNU General Public License and the
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GNU Lesser General Public License along with the GNU MP Library. If not,
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see https://www.gnu.org/licenses/. */
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#include "gmp.h"
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#include "gmp-impl.h"
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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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#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 (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
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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 = SIZ(u);
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vsize = VARIATION SIZ(v);
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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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wp = 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 = PTR(u);
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vp = PTR(v);
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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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SIZ(w) = wsize;
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}
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