imtmdbx.h

// SPDX-License-Identifier: LGPL-2.1-or-later OR GPL-2.0-or-later OR GPL-3.0-or-later OR LicenseRef-ImtCore-Commercial
#pragma once
 
 
// STL includes
#include <array>
#include <cstdint>
 
#if __cplusplus >= 202002L // C++20 or newer
#include <bit.h>
#endif
 
#if defined(_MSC_VER)
#include <intrin.h>
#endif
 
// Qt includes
#include <QtCore/QtTypes>
 
// ACF includes
#include <istd/istd.h>
 
 
namespace imtmdbx
{
 
 
// Maximum value for a 64-bit unsigned integer
static const quint64 QUINT64_MAX = 0xffffffffffffffff;
 
 
namespace BitUtils {
 
 
constexpr std::array<int, 256> MakeBitsSetTable256() {
       std::array<int, 256> table = {};
       for (int i = 0; i < 256; ++i) {
              table[i] = (i & 1) + table[i / 2];
       }
 
       return table;
}
 
// initialize at compile time
inline constexpr std::array<int, 256> BitsSetTable256 = MakeBitsSetTable256();
 
inline int BitCountTable(uint64_t n) {
       return  BitsSetTable256[n & 0xff] +
                     BitsSetTable256[(n >> 8) & 0xff] +
                     BitsSetTable256[(n >> 16) & 0xff] +
                     BitsSetTable256[(n >> 24) & 0xff] +
                     BitsSetTable256[(n >> 32) & 0xff] +
                     BitsSetTable256[(n >> 40) & 0xff] +
                     BitsSetTable256[(n >> 48) & 0xff] +
                     BitsSetTable256[(n >> 56)];
}
 
inline int BitCount(uint64_t n) {
#if __cplusplus >= 202002L
       return std::popcount(n);
#elif defined(_MSC_VER)
       return static_cast<int>(__popcnt64(n));
#elif defined(__GNUG__) || defined(__clang__)
       return __builtin_popcountll(n);
#else
       return BitCountTable(n); // fallback
#endif
}
 
 
}; // namespace BitUtils
 
 
} // namespace imtmdbx