88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
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/*=============================================================================
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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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Copyright (C) 2011 Sebastian Pancratz
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "fmpz.h"
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#include "ulong_extras.h"
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void fmpz_powm(fmpz_t f, const fmpz_t g, const fmpz_t e, const fmpz_t m)
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{
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if (fmpz_sgn(m) <= 0)
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{
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flint_printf("Exception (fmpz_powm). Modulus is less than 1.\n");
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abort();
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}
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else if (!COEFF_IS_MPZ(*e)) /* e is small */
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{
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fmpz_powm_ui(f, g, *e, m);
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}
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else /* e is large */
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{
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if (!COEFF_IS_MPZ(*m)) /* m is small */
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{
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ulong g1 = fmpz_fdiv_ui(g, *m);
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mpz_t g2, m2;
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__mpz_struct *mpz_ptr;
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flint_mpz_init_set_ui(g2, g1);
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flint_mpz_init_set_ui(m2, *m);
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mpz_ptr = _fmpz_promote(f);
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mpz_powm(mpz_ptr, g2, COEFF_TO_PTR(*e), m2);
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mpz_clear(g2);
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mpz_clear(m2);
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_fmpz_demote_val(f);
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}
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else /* m is large */
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{
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if (!COEFF_IS_MPZ(*g)) /* g is small */
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{
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mpz_t g2;
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__mpz_struct *mpz_ptr;
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flint_mpz_init_set_si(g2, *g);
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mpz_ptr = _fmpz_promote(f);
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mpz_powm(mpz_ptr, g2, COEFF_TO_PTR(*e), COEFF_TO_PTR(*m));
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mpz_clear(g2);
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_fmpz_demote_val(f);
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}
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else /* g is large */
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{
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__mpz_struct *mpz_ptr = _fmpz_promote(f);
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mpz_powm(mpz_ptr,
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COEFF_TO_PTR(*g), COEFF_TO_PTR(*e), COEFF_TO_PTR(*m));
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_fmpz_demote_val(f);
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}
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}
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}
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}
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