9291a5fc4d
Reviewers: teon.banek, buda Reviewed By: teon.banek Subscribers: pullbot Differential Revision: https://phabricator.memgraph.io/D1974
27 lines
795 B
C++
27 lines
795 B
C++
#pragma once
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#include <cstdint>
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#include <type_traits>
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#include <glog/logging.h>
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namespace utils {
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static_assert(
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std::is_same_v<uint64_t, unsigned long>,
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"utils::Log requires uint64_t to be implemented as unsigned long.");
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/// This function computes the log2 function on integer types. It is faster than
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/// the cmath `log2` function because it doesn't use floating point values for
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/// calculation.
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inline uint64_t Log2(uint64_t val) {
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// The `clz` function is undefined when the passed value is 0 and the value of
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// `log` is `-inf` so we special case it here.
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if (val == 0) return 0;
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// clzl = count leading zeros from long
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// ^ ^ ^ ^
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int ret = __builtin_clzl(val);
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return 64UL - static_cast<uint64_t>(ret) - 1UL;
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}
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} // namespace utils
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