version 1.1.1.2, 2000/09/09 14:12:58 |
version 1.1.1.3, 2003/08/25 16:06:34 |
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/* mpz_sub_ui -- Subtract an unsigned one-word integer from an MP_INT. |
/* mpz_sub_ui -- Subtract an mpz_t and an unsigned one-word integer. |
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Copyright (C) 1991, 1993, 1994, 1996, 1999 Free Software Foundation, Inc. |
Copyright 2001 Free Software Foundation, Inc. |
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This file is part of the GNU MP Library. |
This file is part of the GNU MP Library. |
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Line 19 along with the GNU MP Library; see the file COPYING.LI |
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Line 19 along with the GNU MP Library; see the file COPYING.LI |
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
MA 02111-1307, USA. */ |
MA 02111-1307, USA. */ |
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#include "gmp.h" |
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#include "gmp-impl.h" |
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void |
#define OPERATION_sub_ui |
#if __STDC__ |
#include "aors_ui.h" |
mpz_sub_ui (mpz_ptr w, mpz_srcptr u, unsigned long int v) |
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#else |
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mpz_sub_ui (w, u, v) |
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mpz_ptr w; |
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mpz_srcptr u; |
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unsigned long int v; |
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#endif |
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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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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] = v; |
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w->_mp_size = -(v != 0); |
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return; |
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} |
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if (usize < 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) v); |
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wp[abs_usize] = cy; |
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wsize = -(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] < v) |
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{ |
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wp[0] = v - up[0]; |
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wsize = -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) v); |
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/* Size can decrease with at most one limb. */ |
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wsize = 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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