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/*=============================================================================
This file is part of FLINT.
FLINT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FLINT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FLINT; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2007 David Howden
Copyright (C) 2010 William Hart
******************************************************************************/
#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "nmod_vec.h"
#include "nmod_poly.h"
#include "fmpz.h"
/* Assumes length > 0, bits > 0. */
void
_nmod_poly_bit_pack(mp_ptr res, mp_srcptr poly, slong len, mp_bitcnt_t bits)
{
slong i;
ulong current_bit = 0, current_limb = 0;
ulong total_limbs = (len * bits - 1) / FLINT_BITS + 1;
mp_limb_t temp_lower, temp_upper;
res[0] = WORD(0);
if (bits < FLINT_BITS)
{
ulong boundary_limit_bit = FLINT_BITS - bits;
for (i = 0; i < len; i++)
{
if (current_bit > boundary_limit_bit)
{
/* the coefficient will be added accross a limb boundary */
temp_lower = (poly[i] << current_bit);
temp_upper = (poly[i] >> (FLINT_BITS - current_bit));
res[current_limb] |= temp_lower;
current_limb++;
res[current_limb] = temp_upper;
current_bit += bits - FLINT_BITS;
}
else
{
/* the coefficient will fit in the current limb */
temp_lower = poly[i] << current_bit;
res[current_limb] |= temp_lower;
current_bit += bits;
if (current_bit == FLINT_BITS)
{
current_limb++;
if (current_limb < total_limbs)
res[current_limb] = WORD(0);
current_bit = 0;
}
}
}
}
else if (bits == FLINT_BITS)
{
for (i = 0; i < len; i++)
res[i] = poly[i];
}
else if (bits == 2 * FLINT_BITS)
{
for (i = 0; i < len; i++)
{
res[current_limb++] = poly[i];
res[current_limb++] = WORD(0);
}
}
else if (bits < 2 * FLINT_BITS)
{
for (i = 0; i < len; i++)
{
/* the coefficient will be added accross a limb boundary */
temp_lower = poly[i] << current_bit;
temp_upper = r_shift(poly[i], FLINT_BITS - current_bit);
res[current_limb++] |= temp_lower;
res[current_limb] = temp_upper;
current_bit += bits - FLINT_BITS;
if (current_bit >= FLINT_BITS)
{
current_bit -= FLINT_BITS;
current_limb++;
if (current_limb < total_limbs)
res[current_limb] = WORD(0);
}
}
}
else /* 2*FLINT_BITS < bits < 3*FLINT_BITS */
{
for (i = 0; i < len; i++)
{
temp_lower = poly[i] << current_bit;
temp_upper = r_shift(poly[i], FLINT_BITS - current_bit);
res[current_limb++] |= temp_lower;
res[current_limb++] = temp_upper;
if (current_limb < total_limbs)
res[current_limb] = WORD(0);
current_bit += bits - 2 * FLINT_BITS;
if (current_bit >= FLINT_BITS)
{
current_bit -= FLINT_BITS;
current_limb++;
if (current_limb < total_limbs)
res[current_limb] = WORD(0);
}
}
}
}
void
nmod_poly_bit_pack(fmpz_t f, const nmod_poly_t poly,
mp_bitcnt_t bit_size)
{
slong len, limbs;
__mpz_struct * mpz;
slong i;
len = nmod_poly_length(poly);
if (len == 0 || bit_size == 0)
{
fmpz_zero(f);
return;
}
mpz = _fmpz_promote(f);
mpz_realloc2(mpz, len * bit_size);
limbs = (len * bit_size - 1) / FLINT_BITS + 1;
_nmod_poly_bit_pack(mpz->_mp_d, poly->coeffs, len, bit_size);
for (i = limbs - 1; i >= 0; i--)
{
if (mpz->_mp_d[i] != 0)
break;
}
mpz->_mp_size = i + 1;
_fmpz_demote_val(f);
}
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