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
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
/* mpz_gcdext(g, s, t, a, b) -- Set G to gcd(a, b), and S and T such that
g = as + bt.
Copyright (C) 1991 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
The GNU MP Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with the GNU MP Library; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "gmp.h"
#include "gmp-impl.h"
/* Botch: SLOW! */
void
#ifdef __STDC__
mpz_gcdext (MP_INT *g, MP_INT *s, MP_INT *t, const MP_INT *a, const MP_INT *b)
#else
mpz_gcdext (g, s, t, a, b)
MP_INT *g;
MP_INT *s;
MP_INT *t;
const MP_INT *a;
const MP_INT *b;
#endif
{
MP_INT s0, s1, q, r, x, d0, d1;
mpz_init_set_ui (&s0, 1);
mpz_init_set_ui (&s1, 0);
mpz_init (&q);
mpz_init (&r);
mpz_init (&x);
mpz_init_set (&d0, a);
mpz_init_set (&d1, b);
while (d1.size != 0)
{
mpz_divmod (&q, &r, &d0, &d1);
mpz_set (&d0, &d1);
mpz_set (&d1, &r);
mpz_mul (&x, &s1, &q);
mpz_sub (&x, &s0, &x);
mpz_set (&s0, &s1);
mpz_set (&s1, &x);
}
if (t != NULL)
{
mpz_mul (&x, &s0, a);
mpz_sub (&x, &d0, &x);
if (b->size == 0)
t->size = 0;
else
mpz_div (t, &x, b);
}
mpz_set (s, &s0);
mpz_set (g, &d0);
mpz_clear (&s0);
mpz_clear (&s1);
mpz_clear (&q);
mpz_clear (&r);
mpz_clear (&x);
mpz_clear (&d0);
mpz_clear (&d1);
}
|
