1 | #include <tommath.h> |
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2 | #ifdef BN_MP_RADIX_SIZE_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 | /* returns size of ASCII reprensentation */ |
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19 | int mp_radix_size (mp_int * a, int radix, int *size) |
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20 | { |
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21 | int res, digs; |
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22 | mp_int t; |
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23 | mp_digit d; |
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24 | |
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25 | *size = 0; |
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26 | |
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27 | /* special case for binary */ |
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28 | if (radix == 2) { |
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29 | *size = mp_count_bits (a) + (a->sign == MP_NEG ? 1 : 0) + 1; |
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30 | return MP_OKAY; |
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31 | } |
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32 | |
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33 | /* make sure the radix is in range */ |
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34 | if (radix < 2 || radix > 64) { |
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35 | return MP_VAL; |
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36 | } |
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37 | |
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38 | if (mp_iszero(a) == MP_YES) { |
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39 | *size = 2; |
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40 | return MP_OKAY; |
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41 | } |
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42 | |
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43 | /* digs is the digit count */ |
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44 | digs = 0; |
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45 | |
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46 | /* if it's negative add one for the sign */ |
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47 | if (a->sign == MP_NEG) { |
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48 | ++digs; |
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49 | } |
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50 | |
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51 | /* init a copy of the input */ |
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52 | if ((res = mp_init_copy (&t, a)) != MP_OKAY) { |
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53 | return res; |
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54 | } |
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55 | |
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56 | /* force temp to positive */ |
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57 | t.sign = MP_ZPOS; |
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58 | |
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59 | /* fetch out all of the digits */ |
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60 | while (mp_iszero (&t) == MP_NO) { |
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61 | if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) { |
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62 | mp_clear (&t); |
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63 | return res; |
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64 | } |
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65 | ++digs; |
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66 | } |
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67 | mp_clear (&t); |
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68 | |
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69 | /* |
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70 | * return digs + 1, the 1 is for the NULL byte that would be required. |
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71 | * mp_toradix_n requires a minimum of 3 bytes, so never report less than |
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72 | * that. |
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73 | */ |
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74 | |
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75 | if ( digs >= 2 ) { |
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76 | *size = digs + 1; |
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77 | } else { |
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78 | *size = 3; |
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79 | } |
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80 | return MP_OKAY; |
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81 | } |
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82 | |
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83 | #endif |
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84 | |
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85 | /* $Source: /cvsroot/tcl/libtommath/bn_mp_radix_size.c,v $ */ |
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86 | /* Tom's revision is 1.4 */ |
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87 | /* $Revision: 1.5 $ */ |
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88 | /* $Date: 2006/12/01 00:31:32 $ */ |
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