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
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
/* mpz/gcd.c: Calculate the greatest common divisor of two integers.
Copyright (C) 1991, 1993, 1994, 1996 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 Library General Public License as published by
the Free Software Foundation; either version 2 of the License, 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 Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the GNU MP Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"
void *_mpz_realloc ();
#ifndef BERKELEY_MP
void
#if __STDC__
mpz_gcd (mpz_ptr g, mpz_srcptr u, mpz_srcptr v)
#else
mpz_gcd (g, u, v)
mpz_ptr g;
mpz_srcptr u;
mpz_srcptr v;
#endif
#else /* BERKELEY_MP */
void
#if __STDC__
gcd (mpz_srcptr u, mpz_srcptr v, mpz_ptr g)
#else
gcd (u, v, g)
mpz_ptr g;
mpz_srcptr u;
mpz_srcptr v;
#endif
#endif /* BERKELEY_MP */
{
unsigned long int g_zero_bits, u_zero_bits, v_zero_bits;
mp_size_t g_zero_limbs, u_zero_limbs, v_zero_limbs;
mp_ptr tp;
mp_ptr up = u->_mp_d;
mp_size_t usize = ABS (u->_mp_size);
mp_ptr vp = v->_mp_d;
mp_size_t vsize = ABS (v->_mp_size);
mp_size_t gsize;
TMP_DECL (marker);
/* GCD(0, V) == V. */
if (usize == 0)
{
g->_mp_size = vsize;
if (g == v)
return;
if (g->_mp_alloc < vsize)
_mpz_realloc (g, vsize);
MPN_COPY (g->_mp_d, vp, vsize);
return;
}
/* GCD(U, 0) == U. */
if (vsize == 0)
{
g->_mp_size = usize;
if (g == u)
return;
if (g->_mp_alloc < usize)
_mpz_realloc (g, usize);
MPN_COPY (g->_mp_d, up, usize);
return;
}
if (usize == 1)
{
g->_mp_size = 1;
g->_mp_d[0] = mpn_gcd_1 (vp, vsize, up[0]);
return;
}
if (vsize == 1)
{
g->_mp_size = 1;
g->_mp_d[0] = mpn_gcd_1 (up, usize, vp[0]);
return;
}
TMP_MARK (marker);
/* Eliminate low zero bits from U and V and move to temporary storage. */
while (*up == 0)
up++;
u_zero_limbs = up - u->_mp_d;
usize -= u_zero_limbs;
count_trailing_zeros (u_zero_bits, *up);
tp = up;
up = (mp_ptr) TMP_ALLOC (usize * BYTES_PER_MP_LIMB);
if (u_zero_bits != 0)
{
mpn_rshift (up, tp, usize, u_zero_bits);
usize -= up[usize - 1] == 0;
}
else
MPN_COPY (up, tp, usize);
while (*vp == 0)
vp++;
v_zero_limbs = vp - v->_mp_d;
vsize -= v_zero_limbs;
count_trailing_zeros (v_zero_bits, *vp);
tp = vp;
vp = (mp_ptr) TMP_ALLOC (vsize * BYTES_PER_MP_LIMB);
if (v_zero_bits != 0)
{
mpn_rshift (vp, tp, vsize, v_zero_bits);
vsize -= vp[vsize - 1] == 0;
}
else
MPN_COPY (vp, tp, vsize);
if (u_zero_limbs > v_zero_limbs)
{
g_zero_limbs = v_zero_limbs;
g_zero_bits = v_zero_bits;
}
else if (u_zero_limbs < v_zero_limbs)
{
g_zero_limbs = u_zero_limbs;
g_zero_bits = u_zero_bits;
}
else /* Equal. */
{
g_zero_limbs = u_zero_limbs;
g_zero_bits = MIN (u_zero_bits, v_zero_bits);
}
/* Call mpn_gcd. The 1st argument must not have more bits than the 2nd. */
vsize = (usize < vsize || (usize == vsize && up[usize-1] < vp[vsize-1]))
? mpn_gcd (vp, up, usize, vp, vsize)
: mpn_gcd (vp, vp, vsize, up, usize);
/* Here G <-- V << (g_zero_limbs*BITS_PER_MP_LIMB + g_zero_bits). */
gsize = vsize + g_zero_limbs;
if (g_zero_bits != 0)
{
mp_limb_t cy_limb;
gsize += (vp[vsize - 1] >> (BITS_PER_MP_LIMB - g_zero_bits)) != 0;
if (g->_mp_alloc < gsize)
_mpz_realloc (g, gsize);
MPN_ZERO (g->_mp_d, g_zero_limbs);
tp = g->_mp_d + g_zero_limbs;
cy_limb = mpn_lshift (tp, vp, vsize, g_zero_bits);
if (cy_limb != 0)
tp[vsize] = cy_limb;
}
else
{
if (g->_mp_alloc < gsize)
_mpz_realloc (g, gsize);
MPN_ZERO (g->_mp_d, g_zero_limbs);
MPN_COPY (g->_mp_d + g_zero_limbs, vp, vsize);
}
g->_mp_size = gsize;
TMP_FREE (marker);
}
|
