116 lines
2.9 KiB
C
116 lines
2.9 KiB
C
/* mpz_add_ui, mpz_sub_ui -- Add or subtract an mpz_t and an unsigned
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one-word integer.
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Copyright 1991, 1993, 1994, 1996, 1999, 2000, 2001, 2002, 2004 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 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 "mpir.h"
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#include "gmp-impl.h"
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#ifdef OPERATION_add_ui
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#define FUNCTION mpz_add_ui
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#define FUNCTION2 mpz_add
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#define VARIATION_CMP >=
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#define VARIATION_NEG
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#define VARIATION_UNNEG -
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#endif
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#ifdef OPERATION_sub_ui
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#define FUNCTION mpz_sub_ui
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#define FUNCTION2 mpz_sub
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#define VARIATION_CMP <
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#define VARIATION_NEG -
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#define VARIATION_UNNEG
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#endif
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#ifndef FUNCTION
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Error, need OPERATION_add_ui or OPERATION_sub_ui
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#endif
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void
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FUNCTION (mpz_ptr w, mpz_srcptr u, mpir_ui vval)
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{
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mp_srcptr up;
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mp_ptr wp;
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mp_size_t usize, wsize;
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mp_size_t abs_usize;
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#if BITS_PER_UI > GMP_NUMB_BITS /* avoid warnings about shift amount */
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if (vval > GMP_NUMB_MAX)
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{
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mpz_t v;
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mp_limb_t vl[2];
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PTR(v) = vl;
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vl[0] = vval & GMP_NUMB_MASK;
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vl[1] = vval >> GMP_NUMB_BITS;
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SIZ(v) = 2;
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FUNCTION2 (w, u, v);
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return;
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}
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#endif
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usize = u->_mp_size;
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abs_usize = ABS (usize);
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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 may be the same as W). */
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up = u->_mp_d;
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wp = w->_mp_d;
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if (abs_usize == 0)
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{
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wp[0] = vval;
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w->_mp_size = VARIATION_NEG (vval != 0);
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return;
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}
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if (usize VARIATION_CMP 0)
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{
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mp_limb_t cy;
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cy = mpn_add_1 (wp, up, abs_usize, (mp_limb_t) vval);
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wp[abs_usize] = cy;
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wsize = VARIATION_NEG (abs_usize + cy);
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}
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else
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{
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/* The signs are different. Need exact comparison to determine
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which operand to subtract from which. */
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if (abs_usize == 1 && up[0] < vval)
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{
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wp[0] = vval - up[0];
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wsize = VARIATION_NEG 1;
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}
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else
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{
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mpn_sub_1 (wp, up, abs_usize, (mp_limb_t) vval);
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/* Size can decrease with at most one limb. */
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wsize = VARIATION_UNNEG (abs_usize - (wp[abs_usize - 1] == 0));
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}
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}
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w->_mp_size = wsize;
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}
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