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https://github.com/FEX-Emu/FEX.git
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Paulo Matos
2b4ec88dae
This follows discussions from #3413. Followup commits add clang-format file, script and blame ignore lists.
83 lines
2.5 KiB
C++
83 lines
2.5 KiB
C++
// SPDX-License-Identifier: MIT
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#pragma once
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// Header for various utilities that operate on bits and bytes.
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#include <bit>
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#include <climits>
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#include <cstddef>
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#include <cstdint>
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#include <cstring>
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#include <type_traits>
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namespace FEXCore {
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// Determines the number of bits inside of a given type.
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template<typename T>
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[[nodiscard]]
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constexpr size_t BitSize() noexcept {
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return sizeof(T) * CHAR_BIT;
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}
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// Swaps the bytes of a 16-bit unsigned value.
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[[nodiscard]]
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inline uint16_t BSwap16(uint16_t value) noexcept {
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#ifdef __GNUC__
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return __builtin_bswap16(value);
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#else
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return (value >> 8) | (value << 8);
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#endif
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}
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// Swaps the bytes of a 32-bit unsigned value.
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[[nodiscard]]
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inline uint32_t BSwap32(uint32_t value) noexcept {
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#ifdef __GNUC__
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return __builtin_bswap32(value);
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#else
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return ((value & 0xFF000000U) >> 24) | ((value & 0x00FF0000U) >> 8) | ((value & 0x0000FF00U) << 8) | ((value & 0x000000FFU) << 24);
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#endif
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}
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// Swaps the bytes of a 64-bit unsigned value.
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[[nodiscard]]
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inline uint64_t BSwap64(uint64_t value) noexcept {
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#ifdef __GNUC__
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return __builtin_bswap64(value);
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#else
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return ((value & 0xFF00000000000000ULL) >> 56) | ((value & 0x00FF000000000000ULL) >> 40) | ((value & 0x0000FF0000000000ULL) >> 24) |
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((value & 0x000000FF00000000ULL) >> 8) | ((value & 0x00000000FF000000ULL) << 8) | ((value & 0x0000000000FF0000ULL) << 24) |
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((value & 0x000000000000FF00ULL) << 40) | ((value & 0x00000000000000FFULL) << 56);
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#endif
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}
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// Finds the first least-significant set bit within a given value.
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// Note that all returned indices are 1-based, not 0-based.
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template<typename T>
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[[nodiscard]]
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constexpr int FindFirstSetBit(T value) noexcept {
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static_assert(std::is_unsigned_v<T>, "Type must be unsigned.");
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if (value == 0) {
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return 0;
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}
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const int trailing_zeroes = std::countr_zero(value);
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return trailing_zeroes + 1;
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}
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// Stand-in for std::bit_cast until libc++ implements it.
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template<typename To, typename From>
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[[nodiscard]]
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inline To BitCast(const From& source) noexcept {
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static_assert(sizeof(From) == sizeof(To), "BitCast source and destination types must be equal in size.");
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static_assert(std::is_trivially_copyable_v<From>, "BitCast source type must be trivially copyable.");
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static_assert(std::is_trivially_copyable_v<To>, "BitCast destination type must be trivially copyable.");
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std::aligned_storage_t<sizeof(To), alignof(To)> storage;
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std::memcpy(&storage, &source, sizeof(storage));
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return reinterpret_cast<To&>(storage);
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}
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} // namespace FEXCore
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