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[Base] Refactor byte_swap 

- Use builtins on non MSVC compilers
- Use `if constexpr` to reduce explicit overloads and SFINAE overhead
This commit is contained in:
Joel Linn 2021-05-22 13:38:53 +02:00 committed by Rick Gibbed
parent 4800194f0d
commit d55192ea30
1 changed files with 22 additions and 53 deletions
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75
src/xenia/base/byte_order.h
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@ -23,10 +23,6 @@
#include "xenia/base/assert.h"
#include "xenia/base/platform.h"
#if XE_PLATFORM_LINUX
#include <byteswap.h>
#endif
#if !__cpp_lib_endian
// Polyfill
#ifdef __BYTE_ORDER__
@ -50,62 +46,35 @@ static_assert((std::endian::native == std::endian::big) ||
namespace xe {
#if XE_PLATFORM_WIN32
#if XE_COMPILER_MSVC
#define XENIA_BASE_BYTE_SWAP_16 _byteswap_ushort
#define XENIA_BASE_BYTE_SWAP_32 _byteswap_ulong
#define XENIA_BASE_BYTE_SWAP_64 _byteswap_uint64
#elif XE_PLATFORM_MAC
#define XENIA_BASE_BYTE_SWAP_16 OSSwapInt16
#define XENIA_BASE_BYTE_SWAP_32 OSSwapInt32
#define XENIA_BASE_BYTE_SWAP_64 OSSwapInt64
#else
#define XENIA_BASE_BYTE_SWAP_16 bswap_16
#define XENIA_BASE_BYTE_SWAP_32 bswap_32
#define XENIA_BASE_BYTE_SWAP_64 bswap_64
#define XENIA_BASE_BYTE_SWAP_16 __builtin_bswap16
#define XENIA_BASE_BYTE_SWAP_32 __builtin_bswap32
#define XENIA_BASE_BYTE_SWAP_64 __builtin_bswap64
#endif // XE_PLATFORM_WIN32
inline int8_t byte_swap(int8_t value) { return value; }
inline uint8_t byte_swap(uint8_t value) { return value; }
inline int16_t byte_swap(int16_t value) {
return static_cast<int16_t>(
XENIA_BASE_BYTE_SWAP_16(static_cast<int16_t>(value)));
}
inline uint16_t byte_swap(uint16_t value) {
return XENIA_BASE_BYTE_SWAP_16(value);
}
inline uint16_t byte_swap(char16_t value) {
return static_cast<char16_t>(XENIA_BASE_BYTE_SWAP_16(value));
}
inline int32_t byte_swap(int32_t value) {
return static_cast<int32_t>(
XENIA_BASE_BYTE_SWAP_32(static_cast<int32_t>(value)));
}
inline uint32_t byte_swap(uint32_t value) {
return XENIA_BASE_BYTE_SWAP_32(value);
}
inline int64_t byte_swap(int64_t value) {
return static_cast<int64_t>(
XENIA_BASE_BYTE_SWAP_64(static_cast<int64_t>(value)));
}
inline uint64_t byte_swap(uint64_t value) {
return XENIA_BASE_BYTE_SWAP_64(value);
}
inline float byte_swap(float value) {
uint32_t temp = byte_swap(*reinterpret_cast<uint32_t*>(&value));
return *reinterpret_cast<float*>(&temp);
}
inline double byte_swap(double value) {
uint64_t temp = byte_swap(*reinterpret_cast<uint64_t*>(&value));
return *reinterpret_cast<double*>(&temp);
}
template <typename T>
template <class T>
inline T byte_swap(T value) {
if (sizeof(T) == 4) {
return static_cast<T>(byte_swap(static_cast<uint32_t>(value)));
} else if (sizeof(T) == 2) {
return static_cast<T>(byte_swap(static_cast<uint16_t>(value)));
} else {
assert_always("not handled");
static_assert(
sizeof(T) == 8 || sizeof(T) == 4 || sizeof(T) == 2 || sizeof(T) == 1,
"byte_swap(T value): Type T has illegal size");
if constexpr (sizeof(T) == 8) {
uint64_t temp =
XENIA_BASE_BYTE_SWAP_64(*reinterpret_cast<uint64_t*>(&value));
return *reinterpret_cast<T*>(&temp);
} else if constexpr (sizeof(T) == 4) {
uint32_t temp =
XENIA_BASE_BYTE_SWAP_32(*reinterpret_cast<uint32_t*>(&value));
return *reinterpret_cast<T*>(&temp);
} else if constexpr (sizeof(T) == 2) {
uint16_t temp =
XENIA_BASE_BYTE_SWAP_16(*reinterpret_cast<uint16_t*>(&value));
return *reinterpret_cast<T*>(&temp);
} else if constexpr (sizeof(T) == 1) {
return value;
}
}