|
142
|
1 #include <tommath.h> |
|
|
2 #ifdef BN_MP_RADIX_SIZE_C |
|
2
|
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis |
|
|
4 * |
|
|
5 * LibTomMath is a library that provides multiple-precision |
|
|
6 * integer arithmetic as well as number theoretic functionality. |
|
|
7 * |
|
|
8 * The library was designed directly after the MPI library by |
|
|
9 * Michael Fromberger but has been written from scratch with |
|
|
10 * additional optimizations in place. |
|
|
11 * |
|
|
12 * The library is free for all purposes without any express |
|
|
13 * guarantee it works. |
|
|
14 * |
|
|
15 * Tom St Denis, [email protected], http://math.libtomcrypt.org |
|
|
16 */ |
|
|
17 |
|
|
18 /* returns size of ASCII reprensentation */ |
|
|
19 int mp_radix_size (mp_int * a, int radix, int *size) |
|
|
20 { |
|
|
21 int res, digs; |
|
|
22 mp_int t; |
|
|
23 mp_digit d; |
|
|
24 |
|
|
25 *size = 0; |
|
|
26 |
|
|
27 /* special case for binary */ |
|
|
28 if (radix == 2) { |
|
|
29 *size = mp_count_bits (a) + (a->sign == MP_NEG ? 1 : 0) + 1; |
|
|
30 return MP_OKAY; |
|
|
31 } |
|
|
32 |
|
|
33 /* make sure the radix is in range */ |
|
|
34 if (radix < 2 || radix > 64) { |
|
|
35 return MP_VAL; |
|
|
36 } |
|
|
37 |
|
|
38 /* init a copy of the input */ |
|
|
39 if ((res = mp_init_copy (&t, a)) != MP_OKAY) { |
|
|
40 return res; |
|
|
41 } |
|
|
42 |
|
|
43 /* digs is the digit count */ |
|
|
44 digs = 0; |
|
|
45 |
|
|
46 /* if it's negative add one for the sign */ |
|
|
47 if (t.sign == MP_NEG) { |
|
|
48 ++digs; |
|
|
49 t.sign = MP_ZPOS; |
|
|
50 } |
|
|
51 |
|
|
52 /* fetch out all of the digits */ |
|
|
53 while (mp_iszero (&t) == 0) { |
|
|
54 if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) { |
|
|
55 mp_clear (&t); |
|
|
56 return res; |
|
|
57 } |
|
|
58 ++digs; |
|
|
59 } |
|
|
60 mp_clear (&t); |
|
|
61 |
|
|
62 /* return digs + 1, the 1 is for the NULL byte that would be required. */ |
|
|
63 *size = digs + 1; |
|
|
64 return MP_OKAY; |
|
|
65 } |
|
|
66 |
|
142
|
67 #endif |
