153 lines
4.4 KiB
C
153 lines
4.4 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) 2008, 2009, William Hart
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Copyright (C) 2010 Fredrik Johansson
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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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#include "nmod_vec.h"
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void
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__fmpz_multi_CRT_ui_sign(fmpz_t output, const fmpz_t input,
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const fmpz_comb_t comb, fmpz_t temp)
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{
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slong n = comb->n;
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slong p;
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if (n == WORD(0))
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{
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if (fmpz_is_zero(input))
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{
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fmpz_zero(output);
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return;
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}
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/* XXX: overflow possible? */
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p = comb->primes[0];
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if ((p - (*input)) < (*input))
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fmpz_set_si(output, (slong) ((*input) - p));
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else
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fmpz_set_ui(output, (*input));
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return;
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}
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fmpz_sub(temp, input, comb->comb[comb->n - 1]);
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if (fmpz_cmpabs(temp, input) <= 0)
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fmpz_set(output, temp);
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else
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fmpz_set(output, input);
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return;
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}
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void fmpz_multi_CRT_ui(fmpz_t output, mp_srcptr residues,
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const fmpz_comb_t comb, fmpz_comb_temp_t ctemp, int sign)
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{
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slong i, j;
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slong n = comb->n;
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slong num;
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slong log_res;
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slong num_primes = comb->num_primes;
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fmpz ** comb_temp = ctemp->comb_temp;
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fmpz * temp = ctemp->temp;
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fmpz * temp2 = ctemp->temp2;
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/* The output is less than a single prime, so just output the result */
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if (num_primes == 1)
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{
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if (sign)
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{
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mp_limb_t p = comb->primes[0];
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if ((p - residues[0]) < residues[0])
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fmpz_set_si(output, residues[0] - p);
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else
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fmpz_set_ui(output, residues[0]);
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}
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else
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{
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fmpz_set_ui(output, residues[0]);
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}
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return;
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}
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/* First layer of reconstruction */
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num = (WORD(1) << n);
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for (i = 0, j = 0; i + 2 <= num_primes; i += 2, j++)
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{
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fmpz_set_ui(temp, residues[i]);
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fmpz_mod_ui(temp2, temp, comb->primes[i+1]);
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fmpz_sub_ui(temp2, temp2, residues[i + 1]);
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fmpz_neg(temp2, temp2);
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fmpz_mul(temp, temp2, comb->res[0] + j);
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fmpz_mod_ui(temp2, temp, comb->primes[i+1]);
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fmpz_mul_ui(temp, temp2, comb->primes[i]);
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fmpz_add_ui(comb_temp[0] + j, temp, residues[i]);
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}
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if (i < num_primes)
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fmpz_set_ui(comb_temp[0] + j, residues[i]);
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/* Compute other layers of reconstruction */
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num /= 2;
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log_res = 1;
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while (log_res < n)
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{
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for (i = 0, j = 0; i < num; i += 2, j++)
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{
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if (fmpz_is_one(comb->comb[log_res-1] + i + 1))
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{
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if (!fmpz_is_one(comb->comb[log_res-1] + i))
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fmpz_set(comb_temp[log_res] + j, comb_temp[log_res-1] + i);
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}
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else
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{
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fmpz_mod(temp2, comb_temp[log_res-1] + i,
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comb->comb[log_res-1] + i + 1);
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fmpz_sub(temp, comb_temp[log_res-1] + i + 1, temp2);
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fmpz_mul(temp2, temp, comb->res[log_res] + j);
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fmpz_mod(temp, temp2, comb->comb[log_res-1] + i + 1);
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fmpz_mul(temp2, temp, comb->comb[log_res-1] + i);
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fmpz_add(comb_temp[log_res] + j, temp2,
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comb_temp[log_res-1] + i);
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}
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}
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log_res++;
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num /= 2;
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}
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/* Write out the output */
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if (sign)
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__fmpz_multi_CRT_ui_sign(output, comb_temp[log_res - 1], comb, temp);
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else
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fmpz_set(output, comb_temp[log_res - 1]);
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}
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