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comparison libtommath/bn_mp_read_radix.c @ 399:a707e6148060

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merge of '5fdf69ca60d1683cdd9f4c2595134bed26394834' and '6b61c50f4cf888bea302ac8fcf5dbb573b443251'
author Matt Johnston <matt@ucc.asn.au>
date Sat, 03 Feb 2007 08:20:34 +0000
parents 5ff8218bcee9
children 60fc6476e044
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394:17d097fc111c 399:a707e6148060
1 #include <tommath.h>
2 #ifdef BN_MP_READ_RADIX_C
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.com
16 */
17
18 /* read a string [ASCII] in a given radix */
19 int mp_read_radix (mp_int * a, const char *str, int radix)
20 {
21 int y, res, neg;
22 char ch;
23
24 /* zero the digit bignum */
25 mp_zero(a);
26
27 /* make sure the radix is ok */
28 if (radix < 2 || radix > 64) {
29 return MP_VAL;
30 }
31
32 /* if the leading digit is a
33 * minus set the sign to negative.
34 */
35 if (*str == '-') {
36 ++str;
37 neg = MP_NEG;
38 } else {
39 neg = MP_ZPOS;
40 }
41
42 /* set the integer to the default of zero */
43 mp_zero (a);
44
45 /* process each digit of the string */
46 while (*str) {
47 /* if the radix < 36 the conversion is case insensitive
48 * this allows numbers like 1AB and 1ab to represent the same value
49 * [e.g. in hex]
50 */
51 ch = (char) ((radix < 36) ? toupper (*str) : *str);
52 for (y = 0; y < 64; y++) {
53 if (ch == mp_s_rmap[y]) {
54 break;
55 }
56 }
57
58 /* if the char was found in the map
59 * and is less than the given radix add it
60 * to the number, otherwise exit the loop.
61 */
62 if (y < radix) {
63 if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) {
64 return res;
65 }
66 if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) {
67 return res;
68 }
69 } else {
70 break;
71 }
72 ++str;
73 }
74
75 /* set the sign only if a != 0 */
76 if (mp_iszero(a) != 1) {
77 a->sign = neg;
78 }
79 return MP_OKAY;
80 }
81 #endif
82
83 /* $Source: /cvs/libtom/libtommath/bn_mp_read_radix.c,v $ */
84 /* $Revision: 1.4 $ */
85 /* $Date: 2006/03/31 14:18:44 $ */