1 /*
2 Copyright (C) 2010 Sebastian Pancratz
3
4 This file is part of FLINT.
5
6 FLINT is free software: you can redistribute it and/or modify it under
7 the terms of the GNU Lesser General Public License (LGPL) as published
8 by the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version. See <http://www.gnu.org/licenses/>.
10 */
11
12 #include <gmp.h>
13 #include "flint.h"
14 #include "fmpz.h"
15 #include "fmpz_poly.h"
16
17 void
_fmpz_poly_reverse(fmpz * res,const fmpz * poly,slong len,slong n)18 _fmpz_poly_reverse(fmpz * res, const fmpz * poly, slong len, slong n)
19 {
20 if (res == poly)
21 {
22 slong i;
23
24 for (i = 0; i < n / 2; i++)
25 {
26 fmpz t = res[i];
27 res[i] = res[n - 1 - i];
28 res[n - 1 - i] = t;
29 }
30
31 for (i = 0; i < n - len; i++)
32 fmpz_zero(res + i);
33 }
34 else
35 {
36 slong i;
37
38 for (i = 0; i < n - len; i++)
39 fmpz_zero(res + i);
40
41 for (i = 0; i < len; i++)
42 fmpz_set(res + (n - len) + i, poly + (len - 1) - i);
43 }
44 }
45
46 void
fmpz_poly_reverse(fmpz_poly_t res,const fmpz_poly_t poly,slong n)47 fmpz_poly_reverse(fmpz_poly_t res, const fmpz_poly_t poly, slong n)
48 {
49 slong len = FLINT_MIN(n, poly->length);
50 if (len == 0)
51 {
52 fmpz_poly_zero(res);
53 return;
54 }
55
56 fmpz_poly_fit_length(res, n);
57
58 _fmpz_poly_reverse(res->coeffs, poly->coeffs, len, n);
59
60 _fmpz_poly_set_length(res, n);
61 _fmpz_poly_normalise(res);
62 }
63