mirror of https://github.com/macssh/macssh.git
124 lines
3.0 KiB
C
124 lines
3.0 KiB
C
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/* mpz_sub -- Subtract two integers.
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Copyright (C) 1991, 1993, 1994, 1996, 2000 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., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, 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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#endif
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#ifndef BERKELEY_MP
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void
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#if __STDC__
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mpz_sub (mpz_ptr w, mpz_srcptr u, mpz_srcptr v)
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#else
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mpz_sub (w, u, v)
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mpz_ptr w;
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mpz_srcptr u;
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mpz_srcptr v;
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#endif
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#else /* BERKELEY_MP */
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void
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#if __STDC__
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msub (mpz_srcptr u, mpz_srcptr v, mpz_ptr w)
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#else
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msub (u, v, w)
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mpz_srcptr u;
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mpz_srcptr v;
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mpz_ptr w;
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#endif
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#endif /* BERKELEY_MP */
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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 = -v->_mp_size; /* The "-" makes the difference from mpz_add */
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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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