247 lines
7.7 KiB
C
247 lines
7.7 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) 2007 David Howden
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Copyright (C) 2010 William Hart
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******************************************************************************/
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#include <stdlib.h>
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#include <gmp.h>
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#include "flint.h"
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#include "nmod_vec.h"
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#include "nmod_poly.h"
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#include "fmpz.h"
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/* Assumes len > 0, bits > 0. */
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void
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_nmod_poly_bit_unpack(mp_ptr res, slong len, mp_srcptr mpn, mp_bitcnt_t bits,
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nmod_t mod)
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{
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slong i;
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ulong current_bit = 0, current_limb = 0;
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mp_limb_t temp_lower, temp_upper, temp_upper2;
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if (bits < FLINT_BITS)
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{
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ulong boundary_limit_bit = FLINT_BITS - bits;
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mp_limb_t mask = (WORD(1) << bits) - WORD(1);
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for (i = 0; i < len; i++)
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{
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if (current_bit > boundary_limit_bit)
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{
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temp_lower = mpn[current_limb++] >> current_bit;
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temp_upper = mpn[current_limb] << (FLINT_BITS - current_bit);
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temp_upper |= temp_lower;
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temp_upper &= mask;
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NMOD_RED(res[i], temp_upper, mod);
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current_bit += bits - FLINT_BITS;
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}
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else
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{
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/* the coeff will fit in the current limb */
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temp_upper = (mpn[current_limb] >> current_bit) & mask;
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NMOD_RED(res[i], temp_upper, mod);
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current_bit += bits;
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if (current_bit == FLINT_BITS)
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{
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current_bit = 0;
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current_limb++;
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}
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}
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}
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}
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else if (bits == FLINT_BITS)
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{
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for (i = 0; i < len; i++)
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NMOD_RED(res[i], mpn[i], mod);
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}
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else if (bits == 2 * FLINT_BITS)
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{
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for (i = 0; i < len; i++)
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{
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NMOD2_RED2(res[i], mpn[current_limb + 1], mpn[current_limb], mod);
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current_limb += 2;
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}
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}
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else if (bits < 2 * FLINT_BITS) /* FLINT_BITS < bits < 2*FLINT_BITS */
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{
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ulong double_boundary_limit_bit = 2 * FLINT_BITS - bits;
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mp_limb_t mask = (WORD(1) << (bits - FLINT_BITS)) - WORD(1);
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for (i = 0; i < len; i++)
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{
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if (current_bit == 0)
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{
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temp_lower = mpn[current_limb++];
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temp_upper = mpn[current_limb] & mask;
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NMOD2_RED2(res[i], temp_upper, temp_lower, mod);
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current_bit = bits - FLINT_BITS;
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}
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else if (current_bit > double_boundary_limit_bit)
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{
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/* the coeff will be across two limb boundaries */
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temp_lower = mpn[current_limb++] >> current_bit;
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temp_lower |=
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(mpn[current_limb] << (FLINT_BITS - current_bit));
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temp_upper = mpn[current_limb++] >> current_bit;
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temp_upper |=
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(mpn[current_limb] << (FLINT_BITS - current_bit));
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temp_upper &= mask;
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NMOD2_RED2(res[i], temp_upper, temp_lower, mod);
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current_bit += bits - 2 * FLINT_BITS;
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}
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else
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{
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/* the coeff will be across one limb boundary */
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temp_lower =
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(mpn[current_limb] >> current_bit) | (mpn[current_limb + 1]
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<< (FLINT_BITS -
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current_bit));
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current_limb++;
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temp_upper = mpn[current_limb] >> current_bit;
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temp_upper &= mask;
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NMOD2_RED2(res[i], temp_upper, temp_lower, mod);
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current_bit += bits - FLINT_BITS;
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if (current_bit == FLINT_BITS)
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{
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current_bit = 0;
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current_limb++;
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}
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}
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}
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}
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else /* 2*FLINT_BITS < bits < 3*FLINT_BITS */
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{
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ulong double_boundary_limit_bit = 3 * FLINT_BITS - bits;
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mp_limb_t mask = (WORD(1) << (bits - 2 * FLINT_BITS)) - WORD(1);
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for (i = 0; i < len; i++)
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{
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if (current_bit == 0)
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{
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temp_lower = mpn[current_limb++];
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temp_upper = mpn[current_limb++];
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temp_upper2 = mpn[current_limb] & mask;
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NMOD_RED3(res[i], temp_upper2, temp_upper, temp_lower, mod);
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current_bit = bits - 2 * FLINT_BITS;
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}
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else if (current_bit <= double_boundary_limit_bit)
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{
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/* the coeff will be across two limb boundaries */
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temp_lower = mpn[current_limb++] >> current_bit;
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temp_lower |=
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(mpn[current_limb] << (FLINT_BITS - current_bit));
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temp_upper = mpn[current_limb++] >> current_bit;
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temp_upper |=
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(mpn[current_limb] << (FLINT_BITS - current_bit));
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temp_upper2 = mpn[current_limb] >> current_bit;
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temp_upper2 &= mask;
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NMOD_RED3(res[i], temp_upper2, temp_upper, temp_lower, mod);
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current_bit += bits - 2 * FLINT_BITS;
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if (current_bit == FLINT_BITS)
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{
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current_bit = 0;
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current_limb++;
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}
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}
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else
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{
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/* the coeff will be across three limb boundaries */
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temp_lower = mpn[current_limb++] >> current_bit;
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temp_lower |=
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(mpn[current_limb] << (FLINT_BITS - current_bit));
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temp_upper = mpn[current_limb++] >> current_bit;
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temp_upper |=
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(mpn[current_limb] << (FLINT_BITS - current_bit));
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temp_upper2 = mpn[current_limb++] >> current_bit;
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temp_upper2 |=
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(mpn[current_limb] << (FLINT_BITS - current_bit));
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temp_upper2 &= mask;
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NMOD_RED3(res[i], temp_upper2, temp_upper, temp_lower, mod);
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current_bit += bits - 3 * FLINT_BITS;
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}
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}
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}
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}
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void
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nmod_poly_bit_unpack(nmod_poly_t poly, const fmpz_t f, mp_bitcnt_t bit_size)
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{
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slong len;
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mpz_t tmp;
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if (fmpz_sgn(f) < 0)
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{
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flint_printf("Exception (nmod_poly_bit_unpack). f < 0.\n");
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abort();
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}
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if (bit_size == 0 || fmpz_is_zero(f))
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{
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nmod_poly_zero(poly);
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return;
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}
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len = (fmpz_bits(f) + bit_size - 1) / bit_size;
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mpz_init2(tmp, bit_size*len);
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flint_mpn_zero(tmp->_mp_d, tmp->_mp_alloc);
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fmpz_get_mpz(tmp, f);
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nmod_poly_fit_length(poly, len);
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_nmod_poly_bit_unpack(poly->coeffs, len, tmp->_mp_d, bit_size, poly->mod);
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poly->length = len;
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_nmod_poly_normalise(poly);
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mpz_clear(tmp);
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}
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