| 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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