42 lines
974 B
C
42 lines
974 B
C
#include <tommath.h>
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#ifdef BN_MP_COUNT_BITS_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is a library that provides multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library was designed directly after the MPI library by
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* Michael Fromberger but has been written from scratch with
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* additional optimizations in place.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
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*/
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/* returns the number of bits in an int */
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int
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mp_count_bits (mp_int * a)
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{
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int r;
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mp_digit q;
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/* shortcut */
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if (a->used == 0) {
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return 0;
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}
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/* get number of digits and add that */
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r = (a->used - 1) * DIGIT_BIT;
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/* take the last digit and count the bits in it */
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q = a->dp[a->used - 1];
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while (q > ((mp_digit) 0)) {
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++r;
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q >>= ((mp_digit) 1);
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}
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return r;
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}
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#endif
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