1 /* $NetBSD: bn_mp_read_radix.c,v 1.1.1.2 2014/04/24 12:45:31 pettai Exp $ */
2
3 #include <tommath.h>
4 #ifdef BN_MP_READ_RADIX_C
5 /* LibTomMath, multiple-precision integer library -- Tom St Denis
6 *
7 * LibTomMath is a library that provides multiple-precision
8 * integer arithmetic as well as number theoretic functionality.
9 *
10 * The library was designed directly after the MPI library by
11 * Michael Fromberger but has been written from scratch with
12 * additional optimizations in place.
13 *
14 * The library is free for all purposes without any express
15 * guarantee it works.
16 *
17 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
18 */
19
20 /* read a string [ASCII] in a given radix */
mp_read_radix(mp_int * a,const char * str,int radix)21 int mp_read_radix (mp_int * a, const char *str, int radix)
22 {
23 int y, res, neg;
24 char ch;
25
26 /* zero the digit bignum */
27 mp_zero(a);
28
29 /* make sure the radix is ok */
30 if (radix < 2 || radix > 64) {
31 return MP_VAL;
32 }
33
34 /* if the leading digit is a
35 * minus set the sign to negative.
36 */
37 if (*str == '-') {
38 ++str;
39 neg = MP_NEG;
40 } else {
41 neg = MP_ZPOS;
42 }
43
44 /* set the integer to the default of zero */
45 mp_zero (a);
46
47 /* process each digit of the string */
48 while (*str) {
49 /* if the radix < 36 the conversion is case insensitive
50 * this allows numbers like 1AB and 1ab to represent the same value
51 * [e.g. in hex]
52 */
53 ch = (char) ((radix < 36) ? toupper (*str) : *str);
54 for (y = 0; y < 64; y++) {
55 if (ch == mp_s_rmap[y]) {
56 break;
57 }
58 }
59
60 /* if the char was found in the map
61 * and is less than the given radix add it
62 * to the number, otherwise exit the loop.
63 */
64 if (y < radix) {
65 if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) {
66 return res;
67 }
68 if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) {
69 return res;
70 }
71 } else {
72 break;
73 }
74 ++str;
75 }
76
77 /* set the sign only if a != 0 */
78 if (mp_iszero(a) != 1) {
79 a->sign = neg;
80 }
81 return MP_OKAY;
82 }
83 #endif
84
85 /* Source: /cvs/libtom/libtommath/bn_mp_read_radix.c,v */
86 /* Revision: 1.5 */
87 /* Date: 2006/12/28 01:25:13 */
88