174 lines
4.9 KiB
C
174 lines
4.9 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) 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 length > 0, bits > 0. */
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void
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_nmod_poly_bit_pack(mp_ptr res, mp_srcptr poly, slong len, mp_bitcnt_t bits)
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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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ulong total_limbs = (len * bits - 1) / FLINT_BITS + 1;
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mp_limb_t temp_lower, temp_upper;
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res[0] = WORD(0);
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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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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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/* the coefficient will be added accross a limb boundary */
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temp_lower = (poly[i] << current_bit);
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temp_upper = (poly[i] >> (FLINT_BITS - current_bit));
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res[current_limb] |= temp_lower;
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current_limb++;
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res[current_limb] = temp_upper;
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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 coefficient will fit in the current limb */
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temp_lower = poly[i] << current_bit;
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res[current_limb] |= temp_lower;
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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_limb++;
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if (current_limb < total_limbs)
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res[current_limb] = WORD(0);
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current_bit = 0;
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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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res[i] = poly[i];
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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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res[current_limb++] = poly[i];
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res[current_limb++] = WORD(0);
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}
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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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/* the coefficient will be added accross a limb boundary */
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temp_lower = poly[i] << current_bit;
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temp_upper = r_shift(poly[i], FLINT_BITS - current_bit);
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res[current_limb++] |= temp_lower;
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res[current_limb] = temp_upper;
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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 -= FLINT_BITS;
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current_limb++;
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if (current_limb < total_limbs)
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res[current_limb] = WORD(0);
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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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for (i = 0; i < len; i++)
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{
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temp_lower = poly[i] << current_bit;
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temp_upper = r_shift(poly[i], FLINT_BITS - current_bit);
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res[current_limb++] |= temp_lower;
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res[current_limb++] = temp_upper;
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if (current_limb < total_limbs)
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res[current_limb] = WORD(0);
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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 -= FLINT_BITS;
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current_limb++;
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if (current_limb < total_limbs)
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res[current_limb] = WORD(0);
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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_pack(fmpz_t f, const nmod_poly_t poly,
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mp_bitcnt_t bit_size)
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{
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slong len, limbs;
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__mpz_struct * mpz;
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slong i;
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len = nmod_poly_length(poly);
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if (len == 0 || bit_size == 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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mpz = _fmpz_promote(f);
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mpz_realloc2(mpz, len * bit_size);
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limbs = (len * bit_size - 1) / FLINT_BITS + 1;
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_nmod_poly_bit_pack(mpz->_mp_d, poly->coeffs, len, bit_size);
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for (i = limbs - 1; i >= 0; i--)
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{
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if (mpz->_mp_d[i] != 0)
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break;
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}
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mpz->_mp_size = i + 1;
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_fmpz_demote_val(f);
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}
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