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/*
Copyright (C) 2011, 2010 Sebastian Pancratz
Copyright (C) 2009, 2008 William Hart
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fmpz.h"
#include "fmpz_mod_poly.h"
void
_fmpz_mod_poly_shift_left(fmpz * res, const fmpz * poly, slong len, slong n)
{
slong i;
/* Copy in reverse to avoid writing over unshifted coefficients */
if (res != poly)
{
for (i = len; i--; )
fmpz_set(res + n + i, poly + i);
}
else
{
for (i = len; i--; )
fmpz_swap(res + n + i, res + i);
}
for (i = 0; i < n; i++)
fmpz_zero(res + i);
}
void fmpz_mod_poly_shift_left(fmpz_mod_poly_t res, const fmpz_mod_poly_t poly,
slong n, const fmpz_mod_ctx_t ctx)
{
if (n == 0)
{
fmpz_mod_poly_set(res, poly, ctx);
return;
}
if (poly->length == 0)
{
fmpz_mod_poly_zero(res, ctx);
return;
}
fmpz_mod_poly_fit_length(res, poly->length + n, ctx);
_fmpz_mod_poly_shift_left(res->coeffs, poly->coeffs, poly->length, n);
_fmpz_mod_poly_set_length(res, poly->length + n);
}