Re: [PATCH] block-sha1: Windows declares ntohl() in winsock2.h
On Tue, 18 Aug 2009, Nicolas Pitre wrote:
> Well... Given that git already uses ntohl/htonl quite extensively in
> its core already, I'd suggest making this more globally available
> instead.
What about something like this?
diff --git a/block-sha1/sha1.c b/block-sha1/sha1.c
index 464cb25..51a27c1 100644
--- a/block-sha1/sha1.c
+++ b/block-sha1/sha1.c
@@ -4,9 +4,7 @@
* and to avoid unnecessary copies into the context array.
*/
-#include <string.h>
-#include <arpa/inet.h>
-
+#include "../git-compat-util.h"
#include "sha1.h"
#if defined(__i386__) || defined(__x86_64__)
diff --git a/compat/bswap.h b/compat/bswap.h
new file mode 100644
index 0000000..b436360
--- /dev/null
+++ b/compat/bswap.h
@@ -0,0 +1,19 @@
+/*
+ * Let's make sure we always have a sane definition for ntohl()/htonl().
+ * Some libraries define those as a function call, just to perform byte
+ * shifting, bringing significant overhead to what should be a sinple
+ * operation.
+ */
+
+#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+
+#define bswap32(x) ({ \
+ unsigned int __res; \
+ __asm__("bswap %0" : "=r" (__res) : "0" (x)); \
+ __res; })
+#undef ntohl
+#undef htonl
+#define ntohl(x) bswap32(x)
+#define htonl(x) bswap32(x)
+
+#endif
diff --git a/git-compat-util.h b/git-compat-util.h
index 9f941e4..000859e 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -176,6 +176,8 @@ extern char *gitbasename(char *);
#endif
#endif
+#include "compat/bswap.h"
+
/* General helper functions */
extern void usage(const char *err) NORETURN;
extern void die(const char *err, ...) NORETURN __attribute__((format (printf, 1, 2)));
Nicolas Pitre <nico@cam.org>