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42 lines
1.0 KiB
C
42 lines
1.0 KiB
C
#include "tommath_private.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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* SPDX-License-Identifier: Unlicense
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*/
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/* returns the number of bits in an int */
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int mp_count_bits(const 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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/* ref: HEAD -> master, tag: v1.1.0 */
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/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
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/* commit time: 2019-01-28 20:32:32 +0100 */
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