60 lines
1.9 KiB
C
60 lines
1.9 KiB
C
/*=============================================================================
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This file is part of FLINT.
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FLINT 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 of the License, or
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(at your option) any later version.
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FLINT 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 FLINT; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2009 William Hart
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "ulong_extras.h"
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#include "fmpz.h"
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void
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fmpz_mul_si(fmpz_t f, const fmpz_t g, slong x)
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{
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fmpz c2 = *g;
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if (x == 0)
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{
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fmpz_zero(f);
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return;
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}
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else if (!COEFF_IS_MPZ(c2)) /* c2 is small */
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{
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mp_limb_t prod[2];
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mp_limb_t uc2 = FLINT_ABS(c2);
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mp_limb_t ux = FLINT_ABS(x);
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/* unsigned limb by limb multiply (assembly for most CPU's) */
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umul_ppmm(prod[1], prod[0], uc2, ux);
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if ((c2 ^ x) < WORD(0))
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fmpz_neg_uiui(f, prod[1], prod[0]);
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else
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fmpz_set_uiui(f, prod[1], prod[0]);
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}
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else /* c2 is large */
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{
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__mpz_struct *mpz_ptr = _fmpz_promote(f); /* ok without val as if aliased both are large */
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flint_mpz_mul_si(mpz_ptr, COEFF_TO_PTR(c2), x);
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}
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}
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