1 /*
2     Copyright (C) 2009 William Hart
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 <https://www.gnu.org/licenses/>.
10 */
11 
12 #include <gmp.h>
13 #include "flint.h"
14 #include "ulong_extras.h"
15 
16 int
n_remove2_precomp(mp_limb_t * n,mp_limb_t p,double ppre)17 n_remove2_precomp(mp_limb_t * n, mp_limb_t p, double ppre)
18 {
19     int exp = 0;
20     mp_limb_t quot, rem = UWORD(0);
21 
22     if (p == 2)
23     {
24         count_trailing_zeros(exp, *n);
25         if (exp)
26             (*n) >>= exp;
27 
28         return exp;
29     }
30 
31     do
32     {
33         if ((*n) < p)
34             break;
35         rem = n_divrem2_precomp(&quot, *n, p, ppre);
36         if (rem)
37             break;
38         exp++;
39         (*n) = quot;
40     } while (1);
41 
42     return exp;
43 }
44