85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
/* mpz_add_ui -- Add an MP_INT and an unsigned one-word integer.
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Copyright (C) 1991 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 General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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The GNU MP Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with the GNU MP Library; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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void
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#ifdef __STDC__
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mpz_add_ui (MP_INT *sum, const MP_INT *add1, mp_limb add2)
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#else
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mpz_add_ui (sum, add1, add2)
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MP_INT *sum;
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const MP_INT *add1;
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mp_limb add2;
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#endif
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{
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mp_srcptr add1p;
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mp_ptr sump;
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mp_size add1size, sumsize;
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mp_size abs_add1size;
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add1size = add1->size;
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abs_add1size = ABS (add1size);
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/* If not space for SUM (and possible carry), increase space. */
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sumsize = abs_add1size + 1;
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if (sum->alloc < sumsize)
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_mpz_realloc (sum, sumsize);
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/* These must be after realloc (ADD1 may be the same as SUM). */
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add1p = add1->d;
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sump = sum->d;
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if (add2 == 0)
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{
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MPN_COPY (sump, add1p, abs_add1size);
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sum->size = add1size;
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return;
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}
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if (abs_add1size == 0)
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{
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sump[0] = add2;
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sum->size = 1;
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return;
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}
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if (add1size >= 0)
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{
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sumsize = mpn_add (sump, add1p, abs_add1size, &add2, 1);
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if (sumsize != 0)
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sump[abs_add1size] = 1;
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sumsize = sumsize + abs_add1size;
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}
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else
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{
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/* The signs are different. Need exact comparision to determine
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which operand to subtract from which. */
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if (abs_add1size == 1 && add1p[0] < add2)
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sumsize = (abs_add1size
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+ mpn_sub (sump, &add2, 1, add1p, 1));
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else
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sumsize = -(abs_add1size
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+ mpn_sub (sump, add1p, abs_add1size, &add2, 1));
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}
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sum->size = sumsize;
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}
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