annotate bn_mp_read_radix.c @ 142:d29b64170cf0 libtommath-orig

import of libtommath 0.32
author Matt Johnston <matt@ucc.asn.au>
date Sun, 19 Dec 2004 11:33:56 +0000
parents 86e0b50a9b58
children d8254fc979e9
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142
d29b64170cf0 import of libtommath 0.32
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1 #include <tommath.h>
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2 #ifdef BN_MP_READ_RADIX_C
2
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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4 *
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5 * LibTomMath is a library that provides multiple-precision
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6 * integer arithmetic as well as number theoretic functionality.
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7 *
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8 * The library was designed directly after the MPI library by
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9 * Michael Fromberger but has been written from scratch with
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10 * additional optimizations in place.
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11 *
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12 * The library is free for all purposes without any express
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13 * guarantee it works.
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14 *
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15 * Tom St Denis, [email protected], http://math.libtomcrypt.org
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16 */
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17
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18 /* read a string [ASCII] in a given radix */
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19 int mp_read_radix (mp_int * a, char *str, int radix)
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20 {
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21 int y, res, neg;
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22 char ch;
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23
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24 /* make sure the radix is ok */
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25 if (radix < 2 || radix > 64) {
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26 return MP_VAL;
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27 }
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28
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29 /* if the leading digit is a
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30 * minus set the sign to negative.
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31 */
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32 if (*str == '-') {
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33 ++str;
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34 neg = MP_NEG;
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35 } else {
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36 neg = MP_ZPOS;
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37 }
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38
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39 /* set the integer to the default of zero */
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40 mp_zero (a);
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41
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42 /* process each digit of the string */
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43 while (*str) {
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44 /* if the radix < 36 the conversion is case insensitive
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45 * this allows numbers like 1AB and 1ab to represent the same value
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46 * [e.g. in hex]
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47 */
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48 ch = (char) ((radix < 36) ? toupper (*str) : *str);
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49 for (y = 0; y < 64; y++) {
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50 if (ch == mp_s_rmap[y]) {
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51 break;
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52 }
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53 }
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54
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55 /* if the char was found in the map
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56 * and is less than the given radix add it
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57 * to the number, otherwise exit the loop.
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58 */
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59 if (y < radix) {
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60 if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) {
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61 return res;
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62 }
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63 if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) {
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64 return res;
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65 }
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66 } else {
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67 break;
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68 }
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69 ++str;
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70 }
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71
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72 /* set the sign only if a != 0 */
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73 if (mp_iszero(a) != 1) {
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74 a->sign = neg;
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75 }
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76 return MP_OKAY;
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77 }
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78 #endif