Uses built-in byte swap if available (Apple) and if bswap_XX is undefined.

Defers to pre-defined version if found (e.g. protobuf). For protobuf case, the definitions are identical and thus include order should not affect results.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/compat/byteswap.h b/src/compat/byteswap.h
index 07ca535728..56f4240e49 100644
--- a/src/compat/byteswap.h
+++ b/src/compat/byteswap.h
@@ -15,6 +15,23 @@
 #include <byteswap.h>
 #endif
 
+#if defined(__APPLE__)
+
+#if !defined(bswap_16)
+
+// Mac OS X / Darwin features; we include a check for bswap_16 because if it is already defined, protobuf has
+// defined these macros for us already; if it isn't, we do it ourselves. In either case, we get the exact same
+// result regardless which path was taken
+#include <libkern/OSByteOrder.h>
+#define bswap_16(x) OSSwapInt16(x)
+#define bswap_32(x) OSSwapInt32(x)
+#define bswap_64(x) OSSwapInt64(x)
+
+#endif // !defined(bswap_16)
+
+#else
+// Non-Mac OS X / non-Darwin
+
 #if HAVE_DECL_BSWAP_16 == 0
 inline uint16_t bswap_16(uint16_t x)
 {
@@ -44,4 +61,6 @@ inline uint64_t bswap_64(uint64_t x)
 }
 #endif // HAVE_DECL_BSWAP64
 
+#endif // defined(__APPLE__)
+
 #endif // BITCOIN_COMPAT_BYTESWAP_H