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142
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1 #include <tommath.h> |
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2 #ifdef BN_MP_COUNT_BITS_C |
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2
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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, [email protected], http://math.libtomcrypt.org |
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16 */ |
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17 |
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18 /* returns the number of bits in an int */ |
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19 int |
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20 mp_count_bits (mp_int * a) |
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21 { |
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22 int r; |
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23 mp_digit q; |
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24 |
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25 /* shortcut */ |
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26 if (a->used == 0) { |
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27 return 0; |
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28 } |
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29 |
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30 /* get number of digits and add that */ |
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31 r = (a->used - 1) * DIGIT_BIT; |
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32 |
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33 /* take the last digit and count the bits in it */ |
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34 q = a->dp[a->used - 1]; |
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35 while (q > ((mp_digit) 0)) { |
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36 ++r; |
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37 q >>= ((mp_digit) 1); |
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38 } |
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39 return r; |
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40 } |
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142
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41 #endif |
