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71c29504af
Utf16View currently assumes host endianness. Add support for specifying either big or little endianness (which we mostly just pipe through to simdutf). This will allow using simdutf facilities with LibTextCodec.
132 lines
3.5 KiB
C++
132 lines
3.5 KiB
C++
/*
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* Copyright (c) 2020, the SerenityOS developers.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Format.h>
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#include <AK/Forward.h>
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#include <AK/Platform.h>
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namespace AK {
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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inline constexpr static bool HostIsLittleEndian = true;
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#else
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inline constexpr static bool HostIsLittleEndian = false;
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#endif
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enum class Endianness {
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Host,
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Big,
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Little,
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};
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template<typename T>
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ALWAYS_INLINE constexpr T convert_between_host_and_little_endian(T value)
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{
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if constexpr (HostIsLittleEndian || sizeof(T) == 1)
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return value;
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else if constexpr (sizeof(T) == 8)
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return static_cast<T>(__builtin_bswap64(static_cast<u64>(value)));
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else if constexpr (sizeof(T) == 4)
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return static_cast<T>(__builtin_bswap32(static_cast<u32>(value)));
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else if constexpr (sizeof(T) == 2)
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return static_cast<T>(__builtin_bswap16(static_cast<u16>(value)));
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else
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static_assert(DependentFalse<T>, "Cannot byte-swap values larger than 64-bits");
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}
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template<typename T>
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ALWAYS_INLINE constexpr T convert_between_host_and_big_endian(T value)
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{
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if constexpr (sizeof(T) == 1 || !HostIsLittleEndian)
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return value;
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else if constexpr (sizeof(T) == 8)
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return static_cast<T>(__builtin_bswap64(static_cast<u64>(value)));
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else if constexpr (sizeof(T) == 4)
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return static_cast<T>(__builtin_bswap32(static_cast<u32>(value)));
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else if constexpr (sizeof(T) == 2)
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return static_cast<T>(__builtin_bswap16(static_cast<u16>(value)));
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else
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static_assert(DependentFalse<T>, "Cannot byte-swap values larger than 64-bits");
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}
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template<typename T>
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ALWAYS_INLINE T convert_between_host_and_network_endian(T value)
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{
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return convert_between_host_and_big_endian(value);
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}
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template<typename T>
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class [[gnu::packed]] LittleEndian {
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public:
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constexpr LittleEndian() = default;
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constexpr LittleEndian(T value)
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: m_value(convert_between_host_and_little_endian(value))
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{
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}
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constexpr operator T() const { return convert_between_host_and_little_endian(m_value); }
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private:
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T m_value { 0 };
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};
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template<typename T>
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class [[gnu::packed]] BigEndian {
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public:
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constexpr BigEndian() = default;
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constexpr BigEndian(T value)
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: m_value(convert_between_host_and_big_endian(value))
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{
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}
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constexpr operator T() const { return convert_between_host_and_big_endian(m_value); }
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private:
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T m_value { 0 };
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};
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template<typename T>
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using NetworkOrdered = BigEndian<T>;
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template<typename T>
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requires(HasFormatter<T>) struct Formatter<LittleEndian<T>> : Formatter<T> {
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};
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template<typename T>
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requires(HasFormatter<T>) struct Formatter<BigEndian<T>> : Formatter<T> {
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};
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template<typename T>
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struct Traits<LittleEndian<T>> : public DefaultTraits<LittleEndian<T>> {
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static constexpr bool is_trivially_serializable() { return Traits<T>::is_trivially_serializable(); }
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};
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template<typename T>
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struct Traits<BigEndian<T>> : public DefaultTraits<BigEndian<T>> {
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static constexpr bool is_trivially_serializable() { return Traits<T>::is_trivially_serializable(); }
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};
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constexpr u16 bitswap(u16 v)
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{
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v = ((v >> 1) & 0x5555) | ((v & 0x5555) << 1); // even & odd bits
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v = ((v >> 2) & 0x3333) | ((v & 0x3333) << 2); // pairs
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v = ((v >> 4) & 0x0F0F) | ((v & 0x0F0F) << 4); // nibbles
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return ((v >> 8) & 0x00FF) | ((v & 0x00FF) << 8); // bytes
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}
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}
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#if USING_AK_GLOBALLY
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using AK::BigEndian;
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using AK::bitswap;
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using AK::LittleEndian;
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using AK::NetworkOrdered;
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#endif
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