anchor.diff:  
   ;;; Test instructions
   
  -(defparameter *test-instructions* #(#x40 #x40 #x40 #x91 #xb0 #xff #x50 #x5a #x51 #xeb #x05 #x52 #x48 #xbe #x02 #x03 #xf4) "Test instructions")
  +(defparameter *test-instructions* #(#x40 #x40 #x40 #x91 #xb0 #xff #x50 #x5a #x51 #x52 #x48 #x4b #x43 #x74 #x03 #xbe #x02 #x03 #xf4) "Test instructions")
  
positive.code: 
  (defun in-8-byte-block-p (opcode block)
    (= (truncate (/ opcode 8)) (/ block 8)))
  
  (defun parse-opcode (opcode)
    "Parse an opcode."
  
negative.code:   (disasm-instr (list "jmp" :op1 (twos-complement (next-instruction) nil))
      (incf (register :ip) (twos-complement (next-instruction) nil))))
  
  (defmacro jmp-short-conditionally (opcode condition mnemonic)
    `(if (= (mod ,opcode #x02) 1)
         (disasm-instr (list (concatenate 'string "jn" ,mnemonic) :op1 (twos-complement (next-instruction) nil))
  	 (unless ,condition
  	   (incf (register :ip) (twos-complement (next-instruction) nil))))
         (disasm-instr (list (concatenate 'string "j" ,mnemonic) :op1 (twos-complement (next-instruction) nil))
  	 (when ,condition
  	   (incf (register :ip) (twos-complement (next-instruction) nil))))))
  
  (defun call-near ()
    (disasm-instr (list "call" :op1 (twos-complement (next-word) t))
  