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
|
#include <tommath.h>
#ifdef BN_MP_REDUCE_IS_2K_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
* LibTomMath is a library that provides multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library was designed directly after the MPI library by
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
*/
/* determines if mp_reduce_2k can be used */
int mp_reduce_is_2k(mp_int *a)
{
int ix, iy, iw;
mp_digit iz;
if (a->used == 0) {
return MP_NO;
} else if (a->used == 1) {
return MP_YES;
} else if (a->used > 1) {
iy = mp_count_bits(a);
iz = 1;
iw = 1;
/* Test every bit from the second digit up, must be 1 */
for (ix = DIGIT_BIT; ix < iy; ix++) {
if ((a->dp[iw] & iz) == 0) {
return MP_NO;
}
iz <<= 1;
if (iz > (mp_digit)MP_MASK) {
++iw;
iz = 1;
}
}
}
return MP_YES;
}
#endif
/* $Source: /cvs/libtom/libtommath/bn_mp_reduce_is_2k.c,v $ */
/* $Revision: 1.3 $ */
/* $Date: 2006/03/31 14:18:44 $ */
|
