1 | #include <tommath.h> |
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2 | #ifdef BN_MP_READ_RADIX_C |
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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, tomstdenis@gmail.com, http://math.libtomcrypt.com |
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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, const 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 | /* zero the digit bignum */ |
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25 | mp_zero(a); |
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26 | |
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27 | /* make sure the radix is ok */ |
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28 | if (radix < 2 || radix > 64) { |
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29 | return MP_VAL; |
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30 | } |
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31 | |
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32 | /* if the leading digit is a |
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33 | * minus set the sign to negative. |
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34 | */ |
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35 | if (*str == '-') { |
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36 | ++str; |
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37 | neg = MP_NEG; |
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38 | } else { |
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39 | neg = MP_ZPOS; |
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40 | } |
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41 | |
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42 | /* set the integer to the default of zero */ |
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43 | mp_zero (a); |
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44 | |
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45 | /* process each digit of the string */ |
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46 | while (*str) { |
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47 | /* if the radix < 36 the conversion is case insensitive |
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48 | * this allows numbers like 1AB and 1ab to represent the same value |
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49 | * [e.g. in hex] |
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50 | */ |
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51 | ch = (char) ((radix < 36) ? toupper (*str) : *str); |
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52 | for (y = 0; y < 64; y++) { |
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53 | if (ch == mp_s_rmap[y]) { |
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54 | break; |
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55 | } |
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56 | } |
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57 | |
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58 | /* if the char was found in the map |
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59 | * and is less than the given radix add it |
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60 | * to the number, otherwise exit the loop. |
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61 | */ |
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62 | if (y < radix) { |
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63 | if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) { |
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64 | return res; |
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65 | } |
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66 | if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) { |
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67 | return res; |
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68 | } |
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69 | } else { |
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70 | break; |
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71 | } |
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72 | ++str; |
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73 | } |
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74 | |
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75 | /* if an illegal character was found, fail. */ |
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76 | |
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77 | if ( *str != '\0' ) { |
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78 | mp_zero( a ); |
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79 | return MP_VAL; |
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80 | } |
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81 | |
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82 | /* set the sign only if a != 0 */ |
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83 | if (mp_iszero(a) != 1) { |
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84 | a->sign = neg; |
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85 | } |
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86 | return MP_OKAY; |
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87 | } |
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88 | #endif |
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89 | |
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90 | /* $Source: /cvsroot/tcl/libtommath/bn_mp_read_radix.c,v $ */ |
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91 | /* Tom's revision is 1.4. */ |
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92 | /* $Revision: 1.5 $ */ |
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93 | /* $Date: 2006/12/01 00:31:32 $ */ |
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94 | |
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