Date: Sat, 2 Feb 2008 22:08:05 +0100

From: Marcus von Appen
To: sdl@lists.libsdl.org
Subject: [SDL] [Patch] SDL-1.2 SDL_revcpy() asm patch for the cld flag

Hi,

as reported through the FreeBSD bug tracking system in SDL 1.2.13 (and
in the 1.2 branch, if I see that correctly) the SDL_revcpy() macro sets
the direction flag (std), but does not clear it afterwards (cld), which
is wrong according to the GCC and SYS V specs.  This can cause some
weird side effects, which in turn can lead to memory corruption.

You can read the full report with a detailed description and test
program at http://www.freebsd.org/cgi/query-pr.cgi?pr=ports/120052

Attached is the submitted patch, which fixes the issue.

Regards
Marcus

--HG--
branch : SDL-1.2

include/SDL_stdinc.h

@@ -331,6 +331,7 @@ do {							\
 	__asm__ __volatile__ (				\
 		"std\n\t"				\
 		"rep ; movsl\n\t"			\
+		"cld\n\t"				\
 		: "=&c" (u0), "=&D" (u1), "=&S" (u2)	\
 		: "0" (n >> 2),				\
 		  "1" (dstp+(n-4)), "2" (srcp+(n-4))	\