#pragma once #include <stdint.h> #include <limits> #include <type_traits> inline uint16_t LO_16(uint32_t x) { return static_cast<uint16_t>(x & 0x0000FFFF); } inline uint16_t HI_16(uint32_t x) { return static_cast<uint16_t>(x >> 16); } inline uint32_t LO_32(uint64_t x) { return static_cast<uint32_t>(x & 0x00000000FFFFFFFF); } inline uint32_t HI_32(uint64_t x) { return static_cast<uint32_t>(x >> 32); } /// Clang also defines __GNUC__ #if defined(__GNUC__) inline unsigned GetValueBitCountImpl(unsigned int value) noexcept { // NOTE: __builtin_clz* have undefined result for zero. return std::numeric_limits<unsigned int>::digits - __builtin_clz(value); } inline unsigned GetValueBitCountImpl(unsigned long value) noexcept { return std::numeric_limits<unsigned long>::digits - __builtin_clzl(value); } inline unsigned GetValueBitCountImpl(unsigned long long value) noexcept { return std::numeric_limits<unsigned long long>::digits - __builtin_clzll(value); } #else /// Stupid implementation for non GCC-like compilers. Can use BSR from x86 instructions set. template <typename T> inline unsigned GetValueBitCountImpl(T value) noexcept { unsigned result = 1; // result == 0 - impossible value, since value cannot be zero value >>= 1; while (value) { value >>= 1; ++result; } return result; } #endif /** * Returns the number of leading 0-bits in `value`, starting at the most significant bit position. * NOTE: value cannot be zero */ template <typename T> static inline unsigned GetValueBitCount(T value) noexcept { using TCvt = std::make_unsigned_t<std::decay_t<T>>; return GetValueBitCountImpl(static_cast<TCvt>(value)); }