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120 lines
3.0 KiB
C++
120 lines
3.0 KiB
C++
#pragma once
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#include <cstring>
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#include <type_traits>
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#if defined(WIN32) || defined(_WIN32) || defined(_MSC_VER)
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#define PLATFORM_WINDOWS
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#elif __APPLE__
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#define PLATFORM_APPLE
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#define PLATFORM_POSIX
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#elif __linux__
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#define PLATFORM_LINUX
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#define PLATFORM_POSIX
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#endif
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#ifdef PLATFORM_LINUX
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#include <byteswap.h>
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#endif
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// reinterpret_cast for value types
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template<typename DstType, typename SrcType>
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inline DstType
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bit_cast(const SrcType& src)
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{
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static_assert(sizeof(SrcType) == sizeof(DstType), "bit_cast must be between same sized types");
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static_assert(std::is_trivially_copyable<SrcType>::value, "SrcType is not trivially copyable.");
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static_assert(std::is_trivially_copyable<DstType>::value, "DstType is not trivially copyable.");
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DstType dst;
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std::memcpy(&dst, &src, sizeof(SrcType));
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return dst;
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}
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// Utility class to swap endian for types of size 1, 2, 4, 8
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// other type sizes are not supported
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template<typename Type, unsigned Size = sizeof(Type)>
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struct byte_swap_t;
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template<typename Type>
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struct byte_swap_t<Type, 1>
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{
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static Type swap(Type src)
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{
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return src;
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}
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};
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template<typename Type>
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struct byte_swap_t<Type, 2>
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{
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static Type swap(Type src)
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{
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#ifdef PLATFORM_WINDOWS
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return bit_cast<Type>(_byteswap_ushort(bit_cast<uint16_t>(src)));
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#elif defined(PLATFORM_APPLE)
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// Apple has no 16-bit byteswap intrinsic
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const uint16_t data = bit_cast<uint16_t>(src);
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return bit_cast<Type>((uint16_t)((data >> 8) | (data << 8)));
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#elif defined(PLATFORM_LINUX)
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return bit_cast<Type>(bswap_16(bit_cast<uint16_t>(src)));
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#endif
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}
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};
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template<typename Type>
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struct byte_swap_t<Type, 4>
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{
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static Type swap(Type src)
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{
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#ifdef PLATFORM_WINDOWS
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return bit_cast<Type>(_byteswap_ulong(bit_cast<uint32_t>(src)));
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#elif defined(PLATFORM_APPLE)
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return bit_cast<Type>(__builtin_bswap32(bit_cast<uint32_t>(src)));
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#elif defined(PLATFORM_LINUX)
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return bit_cast<Type>(bswap_32(bit_cast<uint32_t>(src)));
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#endif
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}
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};
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template<typename Type>
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struct byte_swap_t<Type, 8>
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{
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static Type swap(Type src)
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{
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#ifdef PLATFORM_WINDOWS
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return bit_cast<Type>(_byteswap_uint64(bit_cast<uint64_t>(src)));
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#elif defined(PLATFORM_APPLE)
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return bit_cast<Type>(__builtin_bswap64(bit_cast<uint64_t>(src)));
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#elif defined(PLATFORM_LINUX)
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return bit_cast<Type>(bswap_64(bit_cast<uint64_t>(src)));
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#endif
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}
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};
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// Swaps endian of src
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template<typename Type>
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inline Type
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byte_swap(Type src)
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{
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return byte_swap_t<Type>::swap(src);
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}
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// Alignment helpers
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template<typename Type>
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constexpr inline Type
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align_up(Type value, size_t alignment)
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{
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return static_cast<Type>((static_cast<size_t>(value) + (alignment - 1)) & ~(alignment - 1));
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}
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template<typename Type>
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constexpr inline Type
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align_down(Type value, size_t alignment)
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{
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return static_cast<Type>(static_cast<size_t>(value) & ~(alignment - 1));
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}
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#define CHECK_SIZE(Type, Size) \
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static_assert(sizeof(Type) == Size, \
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#Type " must be " #Size " bytes")
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