anchor.diff:  (make-ee-instructions (make-encoding :spec #b010001 :fixed 0 :rt 16 :fs 11 :inst 21 :type 10 :func #'fpu-type3) 
                         '((mfc1 #b00000) (mtc1 #b00100)))
   
  -;;
   ;; cop-0 instructions
  -;;
   
   (make-ee-instructions (make-encoding :spec #b010000 :fixed #x1000000 :inst 16 :type 3 :func #'inst-type3) 
                         '((bc0f #b00000) (bc0fl #b00010) (bc0t #b00001) (bc0tl #b00011)))
  
positive.code: 
  (defstruct encoding inst (spec 0) rd rs rt (imm 0) (fixed 0) fs ft fd (type 0) func)
  
  ;;
  ;; encode instruction
  ;;
  
  (defun encode-ee-instruction (stream instruction)
    (let ((instruction-info (gethash (first instruction) *mips-instructions*)))
  
negative.code: (make-ee-instructions (make-encoding :inst 0 :type 6 :func #'inst-type6) 
                        '((sync #b00000001111) (sync.l #b00000001111) (sync.p #b10000001111)))
  
  ;; fpu instructions
  
  (make-ee-instructions (make-encoding :imm 0 :inst 26 :fs 21 :ft 16 :type 9 :func #'fpu-type0)
                        '((lwc1 #b110001) (swc1 #b111001)))
  