annotate bn_mp_read_radix.c @ 139:cc04b085e7dd libtommath

Pristine compilation works.
author Matt Johnston <matt@ucc.asn.au>
date Fri, 17 Dec 2004 06:27:22 +0000
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children d29b64170cf0
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1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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2 *
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3 * LibTomMath is a library that provides multiple-precision
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4 * integer arithmetic as well as number theoretic functionality.
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5 *
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6 * The library was designed directly after the MPI library by
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7 * Michael Fromberger but has been written from scratch with
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8 * additional optimizations in place.
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9 *
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10 * The library is free for all purposes without any express
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11 * guarantee it works.
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12 *
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13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
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14 */
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15 #include <tommath.h>
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16
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17 /* read a string [ASCII] in a given radix */
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18 int mp_read_radix (mp_int * a, char *str, int radix)
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19 {
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20 int y, res, neg;
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21 char ch;
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22
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23 /* make sure the radix is ok */
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24 if (radix < 2 || radix > 64) {
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25 return MP_VAL;
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26 }
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27
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28 /* if the leading digit is a
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29 * minus set the sign to negative.
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30 */
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31 if (*str == '-') {
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32 ++str;
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33 neg = MP_NEG;
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34 } else {
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35 neg = MP_ZPOS;
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36 }
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37
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38 /* set the integer to the default of zero */
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39 mp_zero (a);
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40
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41 /* process each digit of the string */
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42 while (*str) {
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43 /* if the radix < 36 the conversion is case insensitive
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44 * this allows numbers like 1AB and 1ab to represent the same value
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45 * [e.g. in hex]
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46 */
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47 ch = (char) ((radix < 36) ? toupper (*str) : *str);
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48 for (y = 0; y < 64; y++) {
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49 if (ch == mp_s_rmap[y]) {
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50 break;
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51 }
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52 }
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53
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54 /* if the char was found in the map
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55 * and is less than the given radix add it
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56 * to the number, otherwise exit the loop.
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57 */
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58 if (y < radix) {
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59 if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) {
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60 return res;
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61 }
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62 if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) {
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63 return res;
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64 }
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65 } else {
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66 break;
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67 }
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68 ++str;
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69 }
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70
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71 /* set the sign only if a != 0 */
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72 if (mp_iszero(a) != 1) {
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73 a->sign = neg;
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74 }
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75 return MP_OKAY;
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76 }