Use faster byte swapping when compiling with MSVC

When compiling with MSVC on x86-compatible, use an intrinsic for byte swapping.
In contrast to the GCC path, we do not prefer inline assembly here as it is not
supported for the x64 platform.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/compat/bswap.h b/compat/bswap.h
index 5cc4acbfccef771769974b9f7cd8f6bca9321354..279e0b48b15e091fc0ca975c3efbd461ab02c149 100644 (file)
--- a/compat/bswap.h
+++ b/compat/bswap.h
@@ -28,6 +28,16 @@ static inline uint32_t default_swab32(uint32_t val)
        } \
        __res; })
 
+#elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
+
+#include <stdlib.h>
+
+#define bswap32(x) _byteswap_ulong(x)
+
+#endif
+
+#ifdef bswap32
+
 #undef ntohl
 #undef htonl
 #define ntohl(x) bswap32(x)