pqc/external/flint-2.4.3/fmpz_vec/scalar_addmul_si_2exp.c

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2014-05-18 22:03:37 +00:00
/*=============================================================================
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) 2010 William Hart
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_vec.h"
void
_fmpz_vec_scalar_addmul_si_2exp(fmpz * vec1, const fmpz * vec2, slong len2,
slong c, ulong exp)
{
slong i;
fmpz_t temp;
if (c == 0)
return; /* nothing to add */
if (exp == 0) /* just do addmul */
{
_fmpz_vec_scalar_addmul_si(vec1, vec2, len2, c);
return;
}
fmpz_init(temp);
if (c == 1) /* scalar is 1, just add c * 2^exp times c */
{
for (i = 0; i < len2; i++)
{
fmpz_mul_2exp(temp, vec2 + i, exp);
fmpz_add(vec1 + i, vec1 + i, temp);
}
}
else if (c == -1) /* scalar is -1, subtract c * 2^exp */
{
for (i = 0; i < len2; i++)
{
fmpz_mul_2exp(temp, vec2 + i, exp);
fmpz_sub(vec1 + i, vec1 + i, temp);
}
}
else /* generic case */
{
if (c > 0)
{
for (i = 0; i < len2; i++)
{
fmpz_mul_2exp(temp, vec2 + i, exp);
fmpz_addmul_ui(vec1 + i, temp, c);
}
}
else
{
for (i = 0; i < len2; i++)
{
fmpz_mul_2exp(temp, vec2 + i, exp);
fmpz_submul_ui(vec1 + i, temp, -c);
}
}
}
fmpz_clear(temp);
}