From 47ca79ba4bc7e5c18cf9427c975a789efd65a414 Mon Sep 17 00:00:00 2001
From: Lioncash <mathew1800@gmail.com>
Date: Sun, 8 May 2016 23:21:44 -0400
Subject: [PATCH] swap: Get rid of undefined behavior in swapf and swapd
This isn't well-defined in C++.
---
src/common/swap.h | 32 ++++++++++++++++++--------------
1 file changed, 18 insertions(+), 14 deletions(-)
diff --git a/src/common/swap.h b/src/common/swap.h
index f51751d29a..beedd6c7ed 100644
--- a/src/common/swap.h
+++ b/src/common/swap.h
@@ -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.");
+
+ u32 value;
+ std::memcpy(&value, &f, sizeof(u32));
- dat1.f = f;
- dat2.u32 = swap32(dat1.u32);
+ value = swap32(value);
+ std::memcpy(&f, &value, sizeof(u32));
- return dat2.f;
+ 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.");
+
+ u64 value;
+ std::memcpy(&value, &f, sizeof(u64));
- dat1.f = f;
- dat2.u64 = swap64(dat1.u64);
+ value = swap64(value);
+ std::memcpy(&f, &value, sizeof(u64));
- return dat2.f;
+ return f;
}
} // Namespace Common
--
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