ntoskrnl.exe: Fix SIB_INDEX() to use REX_X, not REX_R.

[Ken Thomases]

Signed-off-by: Ken Thomases <ken at codeweavers.com>
---
See <http://source.winehq.org/source/programs/winedbg/db_disasm64.c#0992> or
<http://wiki.osdev.org/X86-64_Instruction_Encoding#Encoding>, for confirmation.

 dlls/ntoskrnl.exe/instr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/ntoskrnl.exe/instr.c b/dlls/ntoskrnl.exe/instr.c
index 85b872e..48f16f2 100644
--- a/dlls/ntoskrnl.exe/instr.c
+++ b/dlls/ntoskrnl.exe/instr.c
@@ -492,7 +492,7 @@ WINE_DEFAULT_DEBUG_CHANNEL(int);
 #define REGMODRM_RM( regmodrm, rex )    (((regmodrm) & 7) | (((rex) & REX_B) ? 8 : 0))
 
 #define SIB_SS( sib, rex )      ((sib) >> 6)
-#define SIB_INDEX( sib, rex )   (((sib) >> 3) & 7) | (((rex) & REX_R) ? 8 : 0)
+#define SIB_INDEX( sib, rex )   (((sib) >> 3) & 7) | (((rex) & REX_X) ? 8 : 0)
 #define SIB_BASE( sib, rex )    (((sib) & 7) | (((rex) & REX_B) ? 8 : 0))
 
 /* keep in sync with dlls/ntdll/thread.c:thread_init */
-- 
2.6.0