anchor.diff:  	   ;; displacement is small or even 0, we must use this
   	   ;; encoding.
   	   (multiple-value-bind (rex.x i)
  -	       (floor (code-number index-register) 8)
  +	       (floor index-register 8)
   	     `(,(ash rex.x 1)
   	       #b00000100 ; ModR/M byte
   	       ,(+ (ash (round (log scale 2)) 6)
  
positive.code: 		(null displacement))
  	   ;; We have only a base register.
  	   (multiple-value-bind (rex.b r/m)
  	       (floor (code-number base-register) 8)
  	     (if (= r/m 4)
  		 `(,rex.b
  		   #b00000100  ; ModR/M byte
  
negative.code: 		(typep displacement '(signed-byte 32)))
  	   ;; We have a base register and a 32-bit displacement.
  	   (multiple-value-bind (rex.b r/m)
  	       (floor base-register 8)
  	     (if (= r/m 4)
  		 `(,rex.b
  		   #b10000100 ; ModR/M byte
  