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/*
Copyright (C) 2020 Fredrik Johansson
This file is part of Calcium.
Calcium 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 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "ca_poly.h"
void
_ca_poly_shift_right(ca_ptr res, ca_srcptr poly, slong len, slong n, ca_ctx_t ctx)
{
slong i;
/* Copy in forward order to avoid writing over unshifted coefficients */
if (res != poly)
{
for (i = 0; i < len - n; i++)
ca_set(res + i, poly + n + i, ctx);
}
else
{
for (i = 0; i < len - n; i++)
ca_swap(res + i, res + n + i, ctx);
}
}
void
ca_poly_shift_right(ca_poly_t res, const ca_poly_t poly, slong n, ca_ctx_t ctx)
{
if (n == 0)
{
ca_poly_set(res, poly, ctx);
return;
}
if (poly->length <= n)
{
ca_poly_zero(res, ctx);
return;
}
ca_poly_fit_length(res, poly->length - n, ctx);
_ca_poly_shift_right(res->coeffs, poly->coeffs, poly->length, n, ctx);
_ca_poly_set_length(res, poly->length - n, ctx);
}
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