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view libtommath/bn_mp_count_bits.c @ 1890:45e552ee4391
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author | Matt Johnston <matt@ucc.asn.au> |
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date | Tue, 22 Mar 2022 16:17:47 +0800 |
parents | 1051e4eea25a |
children |
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#include "tommath_private.h" #ifdef BN_MP_COUNT_BITS_C /* LibTomMath, multiple-precision integer library -- Tom St Denis */ /* SPDX-License-Identifier: Unlicense */ /* returns the number of bits in an int */ int mp_count_bits(const mp_int *a) { int r; mp_digit q; /* shortcut */ if (MP_IS_ZERO(a)) { return 0; } /* get number of digits and add that */ r = (a->used - 1) * MP_DIGIT_BIT; /* take the last digit and count the bits in it */ q = a->dp[a->used - 1]; while (q > 0u) { ++r; q >>= 1u; } return r; } #endif