1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
/*
Copyright (C) 2012 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 "mpn_extras.h"
void flint_mpn_preinvn(mp_ptr dinv, mp_srcptr d, mp_size_t n)
{
mp_ptr q, r, d1;
d1 = flint_malloc(n*sizeof(mp_limb_t));
if (mpn_add_1(d1, d, n, 1)) /* check for d + 1 == 0 */
{
mpn_zero(dinv, n);
flint_free(d1);
return;
}
r = flint_malloc((2*n + 1)*sizeof(mp_limb_t));
q = flint_malloc((n + 2)*sizeof(mp_limb_t));
mpn_zero(r, 2*n);
r[2*n] = 1;
mpn_tdiv_qr(q, r, 0, r, 2*n + 1, d1, n);
mpn_copyi(dinv, q, n);
flint_free(r);
flint_free(q);
flint_free(d1);
}