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swap: Get rid of undefined behavior in swapf and swapd

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This isn't well-defined in C++.
This commit is contained in:
Lioncash 2016-05-08 23:21:44 -04:00
parent aef4630102
commit 47ca79ba4b
1 changed files with 18 additions and 14 deletions
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32
src/common/swap.h
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@ -25,6 +25,8 @@
#include <sys/endian.h>
#endif
#include <cstring>
#include "common/common_types.h"
// GCC 4.6+
@ -89,27 +91,29 @@ inline u64 swap64(u64 data) {return ((u64)swap32(data) << 32) | swap32(data >> 3
#endif
inline float swapf(float f) {
union {
float f;
unsigned int u32;
} dat1, dat2;
static_assert(sizeof(u32) == sizeof(float),
"float must be the same size as uint32_t.");
dat1.f = f;
dat2.u32 = swap32(dat1.u32);
u32 value;
std::memcpy(&value, &f, sizeof(u32));
return dat2.f;
value = swap32(value);
std::memcpy(&f, &value, sizeof(u32));
return f;
}
inline double swapd(double f) {
union {
double f;
unsigned long long u64;
} dat1, dat2;
static_assert(sizeof(u64) == sizeof(double),
"double must be the same size as uint64_t.");
dat1.f = f;
dat2.u64 = swap64(dat1.u64);
u64 value;
std::memcpy(&value, &f, sizeof(u64));
return dat2.f;
value = swap64(value);
std::memcpy(&f, &value, sizeof(u64));
return f;
}
} // Namespace Common