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
|
#include "os.h"
#include <mp.h>
/* operands need to have m->top+1 digits of space and satisfy 0 ≤ a ≤ m-1 */
static mpint*
modarg(mpint *a, mpint *m)
{
if(a->size <= m->top || a->sign < 0 || mpmagcmp(a, m) >= 0){
a = mpcopy(a);
mpmod(a, m, a);
mpbits(a, Dbits*(m->top+1));
a->top = m->top;
} else if(a->top < m->top){
memset(&a->p[a->top], 0, (m->top - a->top)*Dbytes);
}
return a;
}
void
mpmodadd(mpint *b1, mpint *b2, mpint *m, mpint *sum)
{
mpint *a, *b;
mpdigit d;
int i, j;
a = modarg(b1, m);
b = modarg(b2, m);
sum->flags |= (a->flags | b->flags) & MPtimesafe;
mpbits(sum, Dbits*2*(m->top+1));
mpvecadd(a->p, m->top, b->p, m->top, sum->p);
mpvecsub(sum->p, m->top+1, m->p, m->top, sum->p+m->top+1);
d = sum->p[2*m->top+1];
for(i = 0, j = m->top+1; i < m->top; i++, j++)
sum->p[i] = (sum->p[i] & d) | (sum->p[j] & ~d);
sum->top = m->top;
sum->sign = 1;
mpnorm(sum);
if(a != b1)
mpfree(a);
if(b != b2)
mpfree(b);
}
void
mpmodsub(mpint *b1, mpint *b2, mpint *m, mpint *diff)
{
mpint *a, *b;
mpdigit d;
int i, j;
a = modarg(b1, m);
b = modarg(b2, m);
diff->flags |= (a->flags | b->flags) & MPtimesafe;
mpbits(diff, Dbits*2*(m->top+1));
a->p[m->top] = 0;
mpvecsub(a->p, m->top+1, b->p, m->top, diff->p);
mpvecadd(diff->p, m->top, m->p, m->top, diff->p+m->top+1);
d = ~diff->p[m->top];
for(i = 0, j = m->top+1; i < m->top; i++, j++)
diff->p[i] = (diff->p[i] & d) | (diff->p[j] & ~d);
diff->top = m->top;
diff->sign = 1;
mpnorm(diff);
if(a != b1)
mpfree(a);
if(b != b2)
mpfree(b);
}
void
mpmodmul(mpint *b1, mpint *b2, mpint *m, mpint *prod)
{
mpint *a, *b;
a = modarg(b1, m);
b = modarg(b2, m);
mpmul(a, b, prod);
mpmod(prod, m, prod);
if(a != b1)
mpfree(a);
if(b != b2)
mpfree(b);
}
|
