anchor.diff:  (make-ee-instructions (make-encoding :spec #b011100 :fixed #b001000 :inst 6 :rs 16 :rt 11 :type 4 :func #'inst-type4)
                         '((pext5  #b11110) (ppac5 #b11111)))
   
  -(make-ee-instructions (make-encoding :spec #b011100 :fixed 0 :inst 0 :rs 21 :rt 16 :type 4 :func #'inst-type4)
  -                      '((pdivbw #b11101001001 ) (pdivw  #b01101001001 ) (pdivuw #b01101 101001 )))
  +(make-ee-instructions (make-encoding :spec #b011100 :imm 0 :fixed 0 :inst 0 :rs 21 :rt 16 :type 4 :func #'inst-type4)
  +                      '((pdivbw #b11101001001 ) (pdivw  #b01101001001 ) (pdivuw #b01101101001 )))
   
   (make-ee-instructions (make-encoding :spec #b011100 :fixed 0 :inst 0 :rs 16 :rt 11 :type 4 :func #'inst-type4)
                         '((pexeh  #b11010001001 ) (pabsh #b00101101000 ) (pabsw #b00001101000 ) (pexew  #b11110001001 )))
  
positive.code: (def-inst-type inst-type3 (() #x0000ffff)) 
  (def-inst-type inst-type4 ((rt rs))) 
  (def-inst-type inst-type5 ((rt))) 
  ; (def-inst-type inst-type6 (())) 
  
  ;; fpu instructions
  
  
negative.code: (make-ee-instructions (make-encoding :spec 0 :inst 0 :rt 21 :imm 0 :type 5 :func #'inst-type5)
                        '((jr #b001000))) 
  
  (make-ee-instructions (make-encoding :spec #b011100 :fixed #b001001 :inst 6 :rt 11 :type 5 :func #'inst-type5)
                         '((pmfhi  #b01000) (pmflo  #b01001)))
  
  (make-ee-instructions (make-encoding :spec #b011100 :imm 0 :inst 0 :rt 11 :type 5 :func #'inst-type5) 
                         '((pmfhl.lh  #b00011110000) (pmfhl.lw #b00000110000) (pmfhl.sh #b00100110000)
                           (pmfhl.slw #b00010110000) (pmfhl.uw #b00001110000))) 
  
  (make-ee-instructions (make-encoding :spec #b011100 :imm 0 :inst 0 :rt 21 :type 5 :func #'inst-type5) 
                         '((pmthi #b01000101001) (pmthl.lw  #b00000110001) (pmtlo #b01001101001)))
  
  (make-ee-instructions (make-encoding :inst 0 :type 6 :func #'inst-type6) 
                        '((sync #b00000001111) (sync.l #b00000001111) (sync.p #b10000001111)))
  
  ;;
  ;; fpu instructions
  