;Copyright (c) 2014 Peter Ferrie
31 c9 41 e2 xx
Returns 0 in ecx if x86, -1 in rcx if x86-64

32-bit decodes to:			
xor	ecx,ecx	;2 bytes
inc	ecx	;ecx=1, 1 byte
loop	l1	;fall through in 32-bit mode, 2 bytes


64-bit decodes to:			
xor	ecx,ecx	;2 bytes
loopq	l1	;REX special bits ignored for inapplicable sets, 3 bytes
32-bit code here:	...		
l1:			
64-bit code:	...