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common/swap: Simplify swap function ifdefs

Including every OS' own built-in byte swapping functions is kind of
undesirable, since it adds yet another build path to ensure compilation
succeeds on.

Given we only support clang, GCC, and MSVC for the time being, we can
utilize their built-in functions directly instead of going through the
OS's API functions.

This shrinks the overall code down to just

if (msvc)
  use msvc's functions
else if (clang or gcc)
  use clang/gcc's builtins
else
  use the slow path
This commit is contained in:
Lioncash 2019-04-11 20:26:37 -04:00
parent 598954436f
commit 9cb4b7be40

View file

@ -21,11 +21,6 @@
#if defined(_MSC_VER)
#include <cstdlib>
#elif defined(__linux__)
#include <byteswap.h>
#elif defined(__Bitrig__) || defined(__DragonFly__) || defined(__FreeBSD__) || \
defined(__NetBSD__) || defined(__OpenBSD__)
#include <sys/endian.h>
#endif
#include <cstring>
#include "common/common_types.h"
@ -62,58 +57,30 @@
namespace Common {
#ifdef _MSC_VER
inline u16 swap16(u16 _data) {
return _byteswap_ushort(_data);
inline u16 swap16(u16 data) {
return _byteswap_ushort(data);
}
inline u32 swap32(u32 _data) {
return _byteswap_ulong(_data);
inline u32 swap32(u32 data) {
return _byteswap_ulong(data);
}
inline u64 swap64(u64 _data) {
return _byteswap_uint64(_data);
inline u64 swap64(u64 data) {
return _byteswap_uint64(data);
}
#elif __linux__
inline u16 swap16(u16 _data) {
return bswap_16(_data);
}
inline u32 swap32(u32 _data) {
return bswap_32(_data);
}
inline u64 swap64(u64 _data) {
return bswap_64(_data);
}
#elif __APPLE__
inline __attribute__((always_inline)) u16 swap16(u16 _data) {
return (_data >> 8) | (_data << 8);
}
inline __attribute__((always_inline)) u32 swap32(u32 _data) {
return __builtin_bswap32(_data);
}
inline __attribute__((always_inline)) u64 swap64(u64 _data) {
return __builtin_bswap64(_data);
}
#elif defined(__Bitrig__) || defined(__OpenBSD__)
#elif defined(__clang__) || defined(__GNUC__)
#if defined(__Bitrig__) || defined(__OpenBSD__)
// redefine swap16, swap32, swap64 as inline functions
#undef swap16
#undef swap32
#undef swap64
inline u16 swap16(u16 _data) {
return __swap16(_data);
#endif
inline u16 swap16(u16 data) {
return __builtin_bswap16(data);
}
inline u32 swap32(u32 _data) {
return __swap32(_data);
inline u32 swap32(u32 data) {
return __builtin_bswap32(data);
}
inline u64 swap64(u64 _data) {
return __swap64(_data);
}
#elif defined(__DragonFly__) || defined(__FreeBSD__) || defined(__NetBSD__)
inline u16 swap16(u16 _data) {
return bswap16(_data);
}
inline u32 swap32(u32 _data) {
return bswap32(_data);
}
inline u64 swap64(u64 _data) {
return bswap64(_data);
inline u64 swap64(u64 data) {
return __builtin_bswap64(data);
}
#else
// Slow generic implementation.