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  1. ; JOYCTL - JOYSTICK MIDI CONTROLLER
  2. ;
  3. ; PHASE ALGORITHM
  4. ;-------------------------------------------
  5. NODATA   NOP                 ;2        NEED 8 CYCLES
  6.          NOP                 ;2
  7.          NOP                 ;2
  8.          NOP                 ;2     
  9. RTMSG    NOP                 ;2        NEED 9 CYCLES
  10.          NOP                 ;2
  11.          NOP                 ;2
  12.          JMP       SWITCH    ;3
  13. ;-------------------------------------------
  14. CHKMIDI  LDA       STS       ;4
  15.          AND       #$01      ;2
  16.          BEQ       NODATA    ;2/3 
  17.          LDA       DTA       ;4
  18.          CMP       #$F8      ;2
  19.          BCS       RTMSG     ;2/3
  20. ;;;      STA       (QHEAD)   ;5                  *65C02*
  21.          DFB       $92
  22.          DFB       QHEAD
  23.          INC       QHEAD     ;5
  24. SWITCH   LDX       PHASE     ;3
  25. ;;;      JMP       (JMPTABLE,X)        ;6        *65C02* ;TOTAL 35 CYCLES
  26.          DFB       $7C
  27.          DFB       JMPTABLE
  28.          DFB       $00
  29. ;-------------------------------------------
  30. P1DONE   LDA       #6        ;2
  31.          STA       PHASE     ;3
  32. ;         BRA       CHKMIDI   ;2        ;25      *65C02*
  33.          DFB       $80
  34.          DFB       $E3
  35. ;
  36. PHASE2   LDA       PDL0      ;4
  37.          BPL       P0DONE    ;2/3
  38.          INC       JOYX      ;5
  39.          LDA       PDL1      ;4
  40.          BPL       P1DONE    ;2/3
  41.          INC       JOYY      ;5
  42.          JMP       CHKMIDI   ;3        ;25
  43. ;
  44. P0DONE   NOP                 ;2
  45.          NOP                 ;2
  46.          NOP                 ;2
  47.          NOP                 ;2
  48.          NOP                 ;2
  49.          LDA       #4        ;2
  50.          STA       PHASE     ;3
  51.          JMP       CHKMIDI   ;3        ;25
  52. ;
  53. ;-------------------------------------------
  54.          CHN       JOYCTL.SC2
  55.