Function CountBits

src/crypto/common.h:90–108

Return the smallest number n such that (x >> n) == 0 (or 64 if the highest bit in x is set. */

/** Return the smallest number n such that (x >> n) == 0 (or 64 if the highest bit in x is set. */
uint64_t static inline CountBits(uint64_t x)
{
#if HAVE_BUILTIN_CLZL
    if (sizeof(unsigned long) >= sizeof(uint64_t)) {
        return x ? 8 * sizeof(unsigned long) - __builtin_clzl(x) : 0;
    }
#endif
#if HAVE_BUILTIN_CLZLL
    if (sizeof(unsigned long long) >= sizeof(uint64_t)) {
        return x ? 8 * sizeof(unsigned long long) - __builtin_clzll(x) : 0;
    }
#endif
    int ret = 0;
    while (x) {
        x >>= 1;
        ++ret;
    }
    return ret;
}

#endif // BITCOIN_CRYPTO_COMMON_H