115 lines
2.8 KiB
C
115 lines
2.8 KiB
C
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/* mpz_mul -- Multiply two integers.
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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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#ifndef BERKELEY_MP
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void
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#ifdef __STDC__
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mpz_mul (MP_INT *w, const MP_INT *u, const MP_INT *v)
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#else
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mpz_mul (w, u, v)
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MP_INT *w;
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const MP_INT *u;
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const MP_INT *v;
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#endif
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#else /* BERKELEY_MP */
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void
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#ifdef __STDC__
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mult (const MP_INT *u, const MP_INT *v, MP_INT *w)
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#else
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mult (u, v, w)
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const MP_INT *u;
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const MP_INT *v;
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MP_INT *w;
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#endif
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#endif /* BERKELEY_MP */
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{
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mp_size usize = u->size;
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mp_size vsize = v->size;
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mp_size wsize;
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mp_size sign_product;
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mp_ptr up, vp;
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mp_ptr wp;
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mp_ptr free_me = NULL;
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size_t free_me_size;
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sign_product = usize ^ vsize;
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usize = ABS (usize);
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vsize = ABS (vsize);
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if (usize < vsize)
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{
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/* Swap U and V. */
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{const MP_INT *t = u; u = v; v = t;}
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{mp_size t = usize; usize = vsize; vsize = t;}
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}
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up = u->d;
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vp = v->d;
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wp = w->d;
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/* Ensure W has space enough to store the result. */
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wsize = usize + vsize;
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if (w->alloc < wsize)
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{
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if (wp == up || wp == vp)
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{
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free_me = wp;
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free_me_size = w->alloc;
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}
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else
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(*_mp_free_func) (wp, w->alloc * BYTES_PER_MP_LIMB);
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w->alloc = wsize;
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wp = (mp_ptr) (*_mp_allocate_func) (wsize * BYTES_PER_MP_LIMB);
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w->d = wp;
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}
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else
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{
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/* Make U and V not overlap with W. */
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if (wp == up)
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{
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/* W and U are identical. Allocate temporary space for U. */
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up = (mp_ptr) alloca (usize * BYTES_PER_MP_LIMB);
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/* Is V identical too? Keep it identical with U. */
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if (wp == vp)
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vp = up;
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/* Copy to the temporary space. */
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MPN_COPY (up, wp, usize);
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}
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else if (wp == vp)
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{
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/* W and V are identical. Allocate temporary space for V. */
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vp = (mp_ptr) alloca (vsize * BYTES_PER_MP_LIMB);
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/* Copy to the temporary space. */
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MPN_COPY (vp, wp, vsize);
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}
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}
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wsize = mpn_mul (wp, up, usize, vp, vsize);
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w->size = sign_product < 0 ? -wsize : wsize;
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if (free_me != NULL)
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(*_mp_free_func) (free_me, free_me_size * BYTES_PER_MP_LIMB);
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alloca (0);
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}
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