| 1 | #include <tommath.h> |
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| 2 | #ifdef BN_MP_TORADIX_N_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 | /* stores a bignum as a ASCII string in a given radix (2..64) |
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| 19 | * |
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| 20 | * Stores upto maxlen-1 chars and always a NULL byte |
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| 21 | */ |
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| 22 | int mp_toradix_n(mp_int * a, char *str, int radix, int maxlen) |
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| 23 | { |
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| 24 | int res, digs; |
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| 25 | mp_int t; |
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| 26 | mp_digit d; |
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| 27 | char *_s = str; |
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| 28 | |
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| 29 | /* check range of the maxlen, radix */ |
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| 30 | if (maxlen < 2 || radix < 2 || radix > 64) { |
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| 31 | return MP_VAL; |
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| 32 | } |
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| 33 | |
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| 34 | /* quick out if its zero */ |
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| 35 | if (mp_iszero(a) == MP_YES) { |
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| 36 | *str++ = '0'; |
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| 37 | *str = '\0'; |
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| 38 | return MP_OKAY; |
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| 39 | } |
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| 40 | |
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| 41 | if ((res = mp_init_copy (&t, a)) != MP_OKAY) { |
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| 42 | return res; |
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| 43 | } |
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| 44 | |
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| 45 | /* if it is negative output a - */ |
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| 46 | if (t.sign == MP_NEG) { |
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| 47 | /* we have to reverse our digits later... but not the - sign!! */ |
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| 48 | ++_s; |
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| 49 | |
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| 50 | /* store the flag and mark the number as positive */ |
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| 51 | *str++ = '-'; |
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| 52 | t.sign = MP_ZPOS; |
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| 53 | |
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| 54 | /* subtract a char */ |
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| 55 | --maxlen; |
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| 56 | } |
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| 57 | |
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| 58 | digs = 0; |
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| 59 | while (mp_iszero (&t) == 0) { |
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| 60 | if (--maxlen < 1) { |
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| 61 | /* no more room */ |
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| 62 | break; |
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| 63 | } |
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| 64 | if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) { |
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| 65 | mp_clear (&t); |
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| 66 | return res; |
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| 67 | } |
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| 68 | *str++ = mp_s_rmap[d]; |
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| 69 | ++digs; |
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| 70 | } |
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| 71 | |
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| 72 | /* reverse the digits of the string. In this case _s points |
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| 73 | * to the first digit [exluding the sign] of the number |
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| 74 | */ |
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| 75 | bn_reverse ((unsigned char *)_s, digs); |
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| 76 | |
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| 77 | /* append a NULL so the string is properly terminated */ |
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| 78 | *str = '\0'; |
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| 79 | |
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| 80 | mp_clear (&t); |
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| 81 | return MP_OKAY; |
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| 82 | } |
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| 83 | |
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| 84 | #endif |
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| 85 | |
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| 86 | /* $Source: /cvsroot/tcl/libtommath/bn_mp_toradix_n.c,v $ */ |
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| 87 | /* $Revision: 1.1.1.4 $ */ |
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| 88 | /* $Date: 2006/12/01 00:08:11 $ */ |
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