diff options
Diffstat (limited to 'src/Endianness.h')
| -rw-r--r-- | src/Endianness.h | 183 |
1 files changed, 120 insertions, 63 deletions
diff --git a/src/Endianness.h b/src/Endianness.h index 0e8bc8e99..c75698587 100644 --- a/src/Endianness.h +++ b/src/Endianness.h @@ -1,86 +1,143 @@ - #pragma once -#undef ntohll -#define ntohll(x) (((static_cast<UInt64>(ntohl(static_cast<UInt32>(x)))) << 32) + ntohl(x >> 32)) - - - - - -// Changes endianness -inline UInt64 HostToNetwork8(const void * a_Value) +#include <array> +template <typename T> +using Bytes = std::array<std::byte, sizeof(T)>; + +// bit_cast used for going between ulong, float, etc. It's a new C++20 feature +#ifdef __cpp_lib_bit_cast +#include <bit> +using std::bit_cast; + +// Fallback in case we're using C++17 +#else +// bit-for-bit convert one type to another. In C++ the only non-UB way to do this is *memcpy*. Nearly every other +// option is a strict aliasing violation. +template<class To, class From> +std::enable_if_t< + sizeof(To) == sizeof(From), + To> +bit_cast(const From &src) noexcept { - UInt64 buf; - memcpy( &buf, a_Value, sizeof( buf)); - buf = (( ( static_cast<UInt64>(htonl(static_cast<UInt32>(buf)))) << 32) + htonl(buf >> 32)); - return buf; + To dst; + std::memcpy(&dst, &src, sizeof(To)); + return dst; } +#endif - - - -inline UInt32 HostToNetwork4(const void * a_Value) +/** Converts a 16-bit host integer or float value to bytes in big-endian (Network) order. +@tparam Value The host 16-bit type (Int16, UInt16). Usually inferred. +@param a_Value The input integer or float value. +@return The resulting bytes. */ +template<typename Value, std::enable_if_t<sizeof(Value) == 2, bool> = true> +inline Bytes<Value> HostToNetwork(Value a_Value) { - UInt32 buf; - memcpy( &buf, a_Value, sizeof( buf)); - buf = ntohl( buf); - return buf; + UInt16 Bits = bit_cast<UInt16>(a_Value); + return + { + std::byte(Bits >> 8), + std::byte(Bits) + }; } - - - - -inline double NetworkToHostDouble8(const void * a_Value) +/** Converts a 32-bit host integer or float value to bytes in big-endian (Network) order. +@tparam Value The host 32-bit type (Int32, UInt32, float). Usually inferred. +@param a_Value The input integer or float value. +@return The resulting bytes. */ +template<typename Value, std::enable_if_t<sizeof(Value) == 4, bool> = true> +inline Bytes<Value> HostToNetwork(Value a_Value) { - UInt64 buf = 0; - memcpy(&buf, a_Value, 8); - buf = ntohll(buf); - double x; - memcpy(&x, &buf, sizeof(double)); - return x; + UInt32 Bits = bit_cast<UInt32>(a_Value); + return + { + std::byte(Bits >> 24), + std::byte(Bits >> 16), + std::byte(Bits >> 8), + std::byte(Bits) + }; } - - - - -inline Int64 NetworkToHostLong8(const void * a_Value) +/** Converts a 64-bit host integer or float value to bytes in big-endian (Network) order. +@tparam Value The host 64-bit type (Int64, UInt64, double). Usually inferred. +@param a_Value The input integer or float value. +@return The resulting bytes. */ +template<typename Value, std::enable_if_t<sizeof(Value) == 8, bool> = true> +inline Bytes<Value> HostToNetwork(Value a_Value) { - UInt64 buf; - memcpy(&buf, a_Value, 8); - buf = ntohll(buf); - return *reinterpret_cast<Int64 *>(&buf); + UInt64 Bits = bit_cast<UInt64>(a_Value); + return + { + std::byte(Bits >> 56), + std::byte(Bits >> 48), + std::byte(Bits >> 40), + std::byte(Bits >> 32), + std::byte(Bits >> 24), + std::byte(Bits >> 16), + std::byte(Bits >> 8), + std::byte(Bits) + }; } - - - - -inline UInt64 NetworkToHostULong8(const void * a_Value) +/** Reads a 16-bit integer or float value from big-endian (Network) bytes. +@tparam Value The desired 16-bit type (Int16, UInt16) +@param a_Value The input bytes. +@return The resulting integer or float value. */ +template<typename Value, std::enable_if_t<sizeof(Value) == 2, bool> = true> +inline Value NetworkToHost(Bytes<Value> a_Value) { - UInt64 buf; - memcpy(&buf, a_Value, 8); - buf = ntohll(buf); - return buf; + UInt16 val = UInt16( + UInt16(a_Value[0]) << 8 | + UInt16(a_Value[1])); + return bit_cast<Value>(val); } - - - - -inline float NetworkToHostFloat4(const void * a_Value) +/** Reads a 32-bit integer or float value from big-endian (Network) bytes. +@tparam Value The desired 32-bit type (Int32, UInt32, float) +@param a_Value The input bytes. +@return The resulting integer or float value. */ +template<typename Value, std::enable_if_t<sizeof(Value) == 4, bool> = true> +inline Value NetworkToHost(Bytes<Value> a_Value) { - UInt32 buf; - float x; - memcpy(&buf, a_Value, 4); - buf = ntohl(buf); - memcpy(&x, &buf, sizeof(float)); - return x; + UInt32 val = UInt32( + UInt32(a_Value[0]) << 24 | + UInt32(a_Value[1]) << 16 | + UInt32(a_Value[2]) << 8 | + UInt32(a_Value[3])); + return bit_cast<Value>(val); } +/** Reads a 64-bit integer or float value from big-endian (Network) bytes. +@tparam Value The desired 64-bit type (Int64, UInt64, double) +@param a_Value The input bytes. +@return The resulting integer or float value. */ +template<typename Value, std::enable_if_t<sizeof(Value) == 8, bool> = true> +inline Value NetworkToHost(Bytes<Value> a_Value) +{ + UInt64 val = UInt64( + UInt64(a_Value[0]) << 56 | + UInt64(a_Value[1]) << 48 | + UInt64(a_Value[2]) << 40 | + UInt64(a_Value[3]) << 32 | + UInt64(a_Value[4]) << 24 | + UInt64(a_Value[5]) << 16 | + UInt64(a_Value[6]) << 8 | + UInt64(a_Value[7])); + return bit_cast<Value>(val); +} +/** Reads an integer or float type from its big-endian (Network) bytes. +@tparam Value The desired result type (Int16 / 32 / 64, UInt16 / 32 / 64, float, double). +@param a_Mem A pointer to the first input byte. Length is inferred from the result type. +@return The resulting integer or float value. - +Consider using NetworkToHost when the data is owned since it provides additional type safety (length is known). */ +template<typename Value> +inline Value NetworkBufToHost(const std::byte* a_Mem) +{ + // Copy unfortunately needed to add the length information required by the rest of the API. + // Gets completely optimised out in my testing. + Bytes<Value> bytes; + std::copy(a_Mem, a_Mem + sizeof(Value), bytes.begin()); + return NetworkToHost<Value>(bytes); +} |