rpcs3/rpcs3/util/endian.hpp
2023-08-17 13:02:57 +03:00

487 lines
11 KiB
C++

#pragma once // No BOM and only basic ASCII in this header, or a neko will die
#include "util/types.hpp"
#ifndef _MSC_VER
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Weffc++"
#endif
namespace stx
{
template <typename T, usz Align = alignof(T), usz Size = sizeof(T)>
struct se_storage
{
struct type8
{
alignas(Align > alignof(T) ? alignof(T) : Align) uchar data[sizeof(T)];
};
struct type64
{
alignas(8) u64 data[sizeof(T) < 8 ? 1 : sizeof(T) / 8];
};
using type = std::conditional_t<(Align >= 8 && sizeof(T) % 8 == 0), type64, type8>;
// Possibly unoptimized generic byteswap for unaligned data
static constexpr type swap(const type& src) noexcept;
};
template <typename T>
struct se_storage<T, 2, 2>
{
using type = u16;
static constexpr u16 swap(u16 src) noexcept
{
#if __cpp_lib_byteswap >= 202110L
return std::byteswap(src);
#elif defined(__GNUG__)
return __builtin_bswap16(src);
#else
if (std::is_constant_evaluated())
{
return (src >> 8) | (src << 8);
}
return _byteswap_ushort(src);
#endif
}
};
template <typename T>
struct se_storage<T, 4, 4>
{
using type = u32;
static constexpr u32 swap(u32 src) noexcept
{
#if __cpp_lib_byteswap >= 202110L
return std::byteswap(src);
#elif defined(__GNUG__)
return __builtin_bswap32(src);
#else
if (std::is_constant_evaluated())
{
const u32 v0 = ((src << 8) & 0xff00ff00) | ((src >> 8) & 0x00ff00ff);
return (v0 << 16) | (v0 >> 16);
}
return _byteswap_ulong(src);
#endif
}
};
template <typename T>
struct se_storage<T, 8, 8>
{
using type = u64;
static constexpr u64 swap(u64 src) noexcept
{
#if __cpp_lib_byteswap >= 202110L
return std::byteswap(src);
#elif defined(__GNUG__)
return __builtin_bswap64(src);
#else
if (std::is_constant_evaluated())
{
const u64 v0 = ((src << 8) & 0xff00ff00ff00ff00) | ((src >> 8) & 0x00ff00ff00ff00ff);
const u64 v1 = ((v0 << 16) & 0xffff0000ffff0000) | ((v0 >> 16) & 0x0000ffff0000ffff);
return (v1 << 32) | (v1 >> 32);
}
return _byteswap_uint64(src);
#endif
}
};
template <typename T, usz Align, usz Size>
constexpr typename se_storage<T, Align, Size>::type se_storage<T, Align, Size>::swap(const type& src) noexcept
{
// Try to keep u16/u32/u64 optimizations at the cost of more bitcasts
if constexpr (sizeof(T) == 1)
{
return src;
}
else if constexpr (sizeof(T) == 2)
{
return std::bit_cast<type>(se_storage<u16>::swap(std::bit_cast<u16>(src)));
}
else if constexpr (sizeof(T) == 4)
{
return std::bit_cast<type>(se_storage<u32>::swap(std::bit_cast<u32>(src)));
}
else if constexpr (sizeof(T) == 8)
{
return std::bit_cast<type>(se_storage<u64>::swap(std::bit_cast<u64>(src)));
}
else if constexpr (sizeof(T) % 8 == 0)
{
type64 tmp = std::bit_cast<type64>(src);
type64 dst{};
// Swap u64 blocks
for (usz i = 0; i < sizeof(T) / 8; i++)
{
dst.data[i] = se_storage<u64>::swap(tmp.data[sizeof(T) / 8 - 1 - i]);
}
return std::bit_cast<type>(dst);
}
else
{
type dst{};
// Swap by moving every byte
for (usz i = 0; i < sizeof(T); i++)
{
dst.data[i] = src.data[sizeof(T) - 1 - i];
}
return dst;
}
}
// Endianness support template
template <typename T, bool Swap, usz Align = alignof(T)>
class alignas(Align) se_t
{
using type = typename std::remove_cv<T>::type;
using stype = typename se_storage<type, Align>::type;
using storage = se_storage<type, Align>;
stype m_data;
static_assert(!std::is_pointer<type>::value, "se_t<> error: invalid type (pointer)");
static_assert(!std::is_reference<type>::value, "se_t<> error: invalid type (reference)");
static_assert(!std::is_array<type>::value, "se_t<> error: invalid type (array)");
static_assert(sizeof(type) == alignof(type), "se_t<> error: unexpected alignment");
static constexpr stype to_data(type value) noexcept
{
if constexpr (Swap)
{
return storage::swap(std::bit_cast<stype>(value));
}
else
{
return std::bit_cast<stype>(value);
}
}
static constexpr auto int_or_enum()
{
if constexpr (std::is_enum_v<type>)
{
return std::underlying_type_t<type>{};
}
else
{
return type{};
}
}
using under = decltype(int_or_enum());
public:
ENABLE_BITWISE_SERIALIZATION;
se_t() noexcept = default;
constexpr se_t(type value) noexcept
: m_data(to_data(value))
{
}
constexpr type value() const noexcept
{
if constexpr (Swap)
{
return std::bit_cast<type>(storage::swap(m_data));
}
else
{
return std::bit_cast<type>(m_data);
}
}
constexpr type get() const noexcept
{
return value();
}
constexpr se_t& operator=(type value) noexcept
{
m_data = to_data(value);
return *this;
}
constexpr operator type() const noexcept
{
return value();
}
#ifdef _MSC_VER
explicit constexpr operator bool() const noexcept
{
static_assert(!type{});
static_assert(!std::is_floating_point_v<type>);
return !!std::bit_cast<type>(m_data);
}
#endif
constexpr auto operator~() const noexcept
{
if constexpr ((std::is_integral_v<T> || std::is_enum_v<T>) && std::is_convertible_v<T, int>)
{
// Return se_t of integral type if possible. Promotion to int is omitted on purpose (a compromise).
return std::bit_cast<se_t<under, Swap>>(static_cast<under>(~std::bit_cast<under>(m_data)));
}
else
{
return ~value();
}
}
private:
// Compatible bit pattern cast
template <typename To, typename Test = int, typename T2>
static constexpr To right_arg_cast(const T2& rhs) noexcept
{
return std::bit_cast<To>(static_cast<se_t<To, Swap>>(rhs));
}
template <typename To, typename Test = int, typename R, usz Align2>
static constexpr To right_arg_cast(const se_t<R, Swap, Align2>& rhs) noexcept
{
if constexpr ((std::is_integral_v<R> || std::is_enum_v<R>) && std::is_convertible_v<R, Test> && sizeof(R) == sizeof(T))
{
// Optimization: allow to reuse bit pattern of any se_t with bit-compatible type
return std::bit_cast<To>(rhs);
}
else
{
return std::bit_cast<To>(static_cast<se_t<To, Swap>>(rhs.value()));
}
}
public:
template <typename T2, typename = decltype(+std::declval<const T2&>())>
constexpr bool operator==(const T2& rhs) const noexcept
{
using R = std::common_type_t<T2>;
if constexpr ((std::is_integral_v<T> || std::is_enum_v<T>) && (std::is_integral_v<R> || std::is_enum_v<R>))
{
if constexpr (sizeof(T) >= sizeof(R))
{
if constexpr (std::is_convertible_v<T, int> && std::is_convertible_v<R, int>)
{
return std::bit_cast<under>(m_data) == right_arg_cast<under>(rhs);
}
else
{
// Compare with strict type on the right side (possibly scoped enum)
return std::bit_cast<type>(m_data) == right_arg_cast<type, type>(rhs);
}
}
}
// Keep outside of if constexpr to make sure it fails on invalid comparison
return value() == rhs;
}
private:
template <typename T2>
static constexpr bool check_args_for_bitwise_op()
{
using R = std::common_type_t<T2>;
if constexpr ((std::is_integral_v<T> || std::is_enum_v<T>) && (std::is_integral_v<R> || std::is_enum_v<R>))
{
if constexpr (std::is_convertible_v<T, int> && std::is_convertible_v<R, int> && sizeof(T) >= sizeof(R))
{
return true;
}
}
return false;
}
public:
template <typename T2>
constexpr auto operator&(const T2& rhs) const noexcept
{
if constexpr (check_args_for_bitwise_op<T2>())
{
return std::bit_cast<se_t<under, Swap>>(static_cast<under>(std::bit_cast<under>(m_data) & right_arg_cast<under>(rhs)));
}
else
{
return value() & rhs;
}
}
template <typename T2>
constexpr auto operator|(const T2& rhs) const noexcept
{
if constexpr (check_args_for_bitwise_op<T2>())
{
return std::bit_cast<se_t<under, Swap>>(static_cast<under>(std::bit_cast<under>(m_data) | right_arg_cast<under>(rhs)));
}
else
{
return value() | rhs;
}
}
template <typename T2>
constexpr auto operator^(const T2& rhs) const noexcept
{
if constexpr (check_args_for_bitwise_op<T2>())
{
return std::bit_cast<se_t<under, Swap>>(static_cast<under>(std::bit_cast<under>(m_data) ^ right_arg_cast<under>(rhs)));
}
else
{
return value() ^ rhs;
}
}
template <typename T1>
constexpr se_t& operator+=(const T1& rhs)
{
*this = value() + rhs;
return *this;
}
template <typename T1>
constexpr se_t& operator-=(const T1& rhs)
{
*this = value() - rhs;
return *this;
}
template <typename T1>
constexpr se_t& operator*=(const T1& rhs)
{
*this = value() * rhs;
return *this;
}
template <typename T1>
constexpr se_t& operator/=(const T1& rhs)
{
*this = value() / rhs;
return *this;
}
template <typename T1>
constexpr se_t& operator%=(const T1& rhs)
{
*this = value() % rhs;
return *this;
}
template <typename T1>
constexpr se_t& operator&=(const T1& rhs)
{
if constexpr (std::is_integral_v<T>)
{
m_data = std::bit_cast<stype, type>(static_cast<type>(std::bit_cast<type>(m_data) & right_arg_cast<type>(rhs)));
return *this;
}
*this = value() & rhs;
return *this;
}
template <typename T1>
constexpr se_t& operator|=(const T1& rhs)
{
if constexpr (std::is_integral_v<T>)
{
m_data = std::bit_cast<stype, type>(static_cast<type>(std::bit_cast<type>(m_data) | right_arg_cast<type>(rhs)));
return *this;
}
*this = value() | rhs;
return *this;
}
template <typename T1>
constexpr se_t& operator^=(const T1& rhs)
{
if constexpr (std::is_integral_v<T>)
{
m_data = std::bit_cast<stype, type>(static_cast<type>(std::bit_cast<type>(m_data) ^ right_arg_cast<type>(rhs)));
return *this;
}
*this = value() ^ rhs;
return *this;
}
template <typename T1>
constexpr se_t& operator<<=(const T1& rhs)
{
*this = value() << rhs;
return *this;
}
template <typename T1>
constexpr se_t& operator>>=(const T1& rhs)
{
*this = value() >> rhs;
return *this;
}
constexpr se_t& operator++()
{
T value = *this;
*this = ++value;
return *this;
}
constexpr se_t& operator--()
{
T value = *this;
*this = --value;
return *this;
}
constexpr T operator++(int)
{
T value = *this;
T result = value++;
*this = value;
return result;
}
constexpr T operator--(int)
{
T value = *this;
T result = value--;
*this = value;
return result;
}
};
}
// Specializations
template <typename T, bool Swap, usz Align, typename T2, bool Swap2, usz Align2>
struct std::common_type<stx::se_t<T, Swap, Align>, stx::se_t<T2, Swap2, Align2>> : std::common_type<T, T2> {};
template <typename T, bool Swap, usz Align, typename T2>
struct std::common_type<stx::se_t<T, Swap, Align>, T2> : std::common_type<T, std::common_type_t<T2>> {};
template <typename T, typename T2, bool Swap2, usz Align2>
struct std::common_type<T, stx::se_t<T2, Swap2, Align2>> : std::common_type<std::common_type_t<T>, T2> {};
#ifndef _MSC_VER
#pragma GCC diagnostic pop
#endif