1.1 --- a/build.py	Sun Aug 14 13:33:50 2011 +0200
     1.2 +++ b/build.py	Sun Aug 14 20:58:00 2011 +0200
     1.3 @@ -49,15 +49,13 @@
     1.4      # Planned memory map
     1.5      # 1900 CODE (map)
     1.6      # 1x00 space
     1.7 -    # 3300 character table (0xf0/8 = 30 entries)
     1.8 +    # 3300 character table (0xf0/6 = 40 entries)
     1.9      #   n   type (0 missing, 1 player, 2 projectile, 3 explosion, 4)
    1.10 -    #   n+1 counter/direction
    1.11 -    #   n+2 x room offset (0-10)
    1.12 -    #   n+3 y room offset (0-10)
    1.13 -    #   n+4 screen address (low byte)
    1.14 -    #   n+5 screen address (high byte)
    1.15 -    #   n+6 dx (0-3)
    1.16 -    #   n+7 dy (0-5)
    1.17 +    #   n+1 counter/direction (player: bit 1 is direction, bit 0 is animation)
    1.18 +    #   n+2 y room offset (0-10)
    1.19 +    #   n+3 dy (0-5)
    1.20 +    #   n+4 x room offset (0-10)
    1.21 +    #   n+5 dx (0-3)
    1.22      #
    1.23      #   first character is always the player
    1.24      #   second character is always the player's weapon

     2.1 --- a/mapcode.oph	Sun Aug 14 13:33:50 2011 +0200
     2.2 +++ b/mapcode.oph	Sun Aug 14 20:58:00 2011 +0200
     2.3 @@ -23,38 +23,42 @@
     2.4      clc
     2.5      rts             ; A % 9
     2.6  
     2.7 +tile_values_map: .byte 0,1,0,0,0,0,2,3
     2.8 +
     2.9  next_value:         ; no argument
    2.10      jsr unlimited_values
    2.11      lda $7d
    2.12      jsr div9
    2.13 -    and #7
    2.14 +    and #7          ; (next value % 9) & 7
    2.15 +    tax
    2.16 +    lda tile_values_map,x
    2.17      sta $7b
    2.18 -    rts             ; $7b = (next value % 9) & 3
    2.19 +    rts
    2.20  
    2.21  ; Room filling routines, writing to 0x579c to 0x57ff.
    2.22  
    2.23  draw_top_line:
    2.24      ldx #9
    2.25 -    lda #6
    2.26 +    lda #2
    2.27  
    2.28      draw_top_line_loop0:
    2.29 -        sta $57f6,x
    2.30 +        sta $579c,x
    2.31          dex
    2.32          bpl draw_top_line_loop0
    2.33  
    2.34 -    ldx #3
    2.35 +    ldx #3                      ; draw the exit or wall
    2.36      lda $76
    2.37      draw_top_line_loop1:
    2.38 -        sta $57f9,x
    2.39 +        sta $579f,x
    2.40          dex
    2.41          bpl draw_top_line_loop1
    2.42      clc
    2.43      rts
    2.44  
    2.45  draw_left_line:
    2.46 -    ldx #99
    2.47 +    ldx #90
    2.48      draw_left_line_loop0:
    2.49 -        lda #6
    2.50 +        lda #2
    2.51          sta $579c,x
    2.52          txa
    2.53          sec
    2.54 @@ -62,7 +66,7 @@
    2.55          tax
    2.56          bpl draw_left_line_loop0
    2.57  
    2.58 -    ldx #39
    2.59 +    ldx #30
    2.60      draw_left_line_loop1:
    2.61          lda $77
    2.62          sta $57ba,x
    2.63 @@ -76,25 +80,25 @@
    2.64  
    2.65  draw_bottom_line:
    2.66      ldx #9
    2.67 -    lda #6
    2.68 +    lda #2
    2.69      draw_bottom_line_loop0:
    2.70 -        sta $579c,x
    2.71 +        sta $57f6,x
    2.72          dex
    2.73          bpl draw_bottom_line_loop0
    2.74  
    2.75      ldx #3
    2.76      lda $76
    2.77      draw_bottom_line_loop1:
    2.78 -        sta $579f,x
    2.79 +        sta $57f9,x
    2.80          dex
    2.81          bpl draw_bottom_line_loop1
    2.82      clc
    2.83      rts
    2.84  
    2.85  draw_right_line:
    2.86 -    ldx #90
    2.87 +    ldx #99
    2.88      draw_right_line_loop0:
    2.89 -        lda #6
    2.90 +        lda #2
    2.91          sta $579c,x
    2.92          txa
    2.93          sec
    2.94 @@ -105,7 +109,7 @@
    2.95      ldx #30
    2.96      draw_right_line_loop1:
    2.97          lda $77
    2.98 -        sta $57ba,x
    2.99 +        sta $57c3,x
   2.100          txa
   2.101          sec
   2.102          sbc #10
   2.103 @@ -116,14 +120,24 @@
   2.104  
   2.105  make_room:          ; $78,$79=i,j
   2.106  
   2.107 -; Determine if there is a top exit.
   2.108 +    ; Fill the room with empty space.
   2.109 +
   2.110 +    ldx #100
   2.111 +    make_empty_room_loop:
   2.112 +        lda #0
   2.113 +        sta $579c,x
   2.114 +        dex
   2.115 +        bpl make_empty_room_loop
   2.116 +
   2.117 +    ; Determine if there is a top exit.
   2.118 +
   2.119      lda #0
   2.120      sta $76
   2.121  
   2.122      lda $78         ; i == 0
   2.123      cmp #0
   2.124      bne not_top_screen
   2.125 -    lda #6
   2.126 +    lda #2
   2.127      sta $76
   2.128      jmp do_top_exit
   2.129  not_top_screen:
   2.130 @@ -144,7 +158,7 @@
   2.131      clc
   2.132      cmp $79         ; (i ^ j) + i == j
   2.133      bne do_top_exit
   2.134 -    lda #6
   2.135 +    lda #2
   2.136      sta $76         ; top exit
   2.137  
   2.138  do_top_exit:
   2.139 @@ -157,7 +171,7 @@
   2.140      lda $79
   2.141      cmp #0
   2.142      bne not_left_screen
   2.143 -    lda #6
   2.144 +    lda #2
   2.145      sta $77
   2.146      jmp do_left_exit
   2.147  not_left_screen:
   2.148 @@ -177,7 +191,7 @@
   2.149      eor $79         ; ^ j
   2.150      cmp $78         ; (i | j) ^ j == i
   2.151      bne do_left_exit
   2.152 -    lda #6
   2.153 +    lda #2
   2.154      sta $77         ; left exit
   2.155  
   2.156  do_left_exit:
   2.157 @@ -190,7 +204,7 @@
   2.158      lda $79
   2.159      cmp #10
   2.160      bne not_right_screen
   2.161 -    lda #6
   2.162 +    lda #2
   2.163      sta $77
   2.164      jmp do_right_exit
   2.165  not_right_screen:
   2.166 @@ -215,7 +229,7 @@
   2.167      eor $70         ; ^ j
   2.168      cmp $78         ; (i | j) ^ j == i
   2.169      bne do_right_exit
   2.170 -    lda #6
   2.171 +    lda #2
   2.172      sta $77         ; right exit
   2.173  
   2.174  do_right_exit:
   2.175 @@ -228,7 +242,7 @@
   2.176      lda $78
   2.177      cmp #10
   2.178      bne not_bottom_screen
   2.179 -    lda #6
   2.180 +    lda #2
   2.181      sta $76
   2.182      jmp do_bottom_exit
   2.183  not_bottom_screen:
   2.184 @@ -252,7 +266,7 @@
   2.185      adc $70         ; + i
   2.186      cmp $79         ; (i ^ j) + i == j
   2.187      bne do_bottom_exit
   2.188 -    lda #6
   2.189 +    lda #2
   2.190      sta $76         ; bottom exit
   2.191  
   2.192  do_bottom_exit:
   2.193 @@ -267,28 +281,9 @@
   2.194      cmp $33f1
   2.195      bne not_starting_room
   2.196  
   2.197 -    clc
   2.198 -
   2.199 -    ; Fill the room with empty space.
   2.200 -
   2.201 -    ldx #78
   2.202 -    ldy #63
   2.203 -    make_empty_room_loop:
   2.204 -        lda #0
   2.205 -        sta $57a6,x
   2.206 -        dey
   2.207 -        tya
   2.208 -        and #7
   2.209 -        cmp #7
   2.210 -        bne finished_empty_room
   2.211 -    dex
   2.212 -    dex
   2.213 -
   2.214 -finished_empty_room:
   2.215 -    clc
   2.216      rts
   2.217  
   2.218 -not_starting_room:
   2.219 +    not_starting_room:
   2.220      clc
   2.221  
   2.222      ; Fill in the room details.
   2.223 @@ -314,24 +309,30 @@
   2.224      
   2.225      ; Fill the room array with values.
   2.226  
   2.227 -    ldx #78
   2.228 -    ldy #63
   2.229 +    lda #$a7
   2.230 +    sta $70
   2.231 +    lda #$57
   2.232 +    sta $71
   2.233 +
   2.234 +    ldy #0
   2.235      make_room_loop1:
   2.236 +
   2.237          jsr next_value
   2.238 -        sta $57a6,x
   2.239 -        dey
   2.240 -        tya
   2.241 -        and #7
   2.242 -        cmp #7
   2.243 -        bne next1
   2.244 -    dex
   2.245 -    dex
   2.246 +        sta ($70),y
   2.247 +        iny
   2.248 +        cpy #8
   2.249 +        bne make_room_loop1     ; continue the same row
   2.250  
   2.251 -next1:
   2.252 -    clc
   2.253 -    dex
   2.254 -    bpl make_room_loop1
   2.255 +        lda $70
   2.256 +        cmp #$ed
   2.257 +        beq make_room_loop1_exit    ; exit after the last row
   2.258 +
   2.259 +        adc #10
   2.260 +        sta $70
   2.261 +        ldy #0                  ; reset the row counter
   2.262 +        jmp make_room_loop1
   2.263      
   2.264 +    make_room_loop1_exit:
   2.265      rts
   2.266  
   2.267  
   2.268 @@ -452,7 +453,7 @@
   2.269      jmp plot_not_blank
   2.270  
   2.271  not_flowers:
   2.272 -    cmp #6
   2.273 +    cmp #2
   2.274      bne not_tree1
   2.275      lda #$60
   2.276      sta $70
   2.277 @@ -461,7 +462,7 @@
   2.278      jmp plot_not_blank
   2.279  
   2.280  not_tree1:
   2.281 -    cmp #7
   2.282 +    cmp #3
   2.283      bne not_tree2
   2.284      lda #$c0
   2.285      sta $70
   2.286 @@ -511,7 +512,7 @@
   2.287  
   2.288      jsr make_room
   2.289  
   2.290 -    lda #99
   2.291 +    lda #0
   2.292      sta $7a
   2.293      row_loop:
   2.294  
   2.295 @@ -526,8 +527,7 @@
   2.296              jsr plot_tile
   2.297  
   2.298              lda $7a
   2.299 -            sec
   2.300 -            sbc #1
   2.301 +            adc #1
   2.302              sta $7a
   2.303              lda $76
   2.304              sec
   2.305 @@ -580,6 +580,7 @@
   2.306  
   2.307      plotloop8x24_y0_0:
   2.308          lda ($70),y
   2.309 +        eor ($72),y
   2.310          sta ($72),y
   2.311          dey
   2.312          bpl plotloop8x24_y0_0
   2.313 @@ -597,6 +598,7 @@
   2.314  
   2.315      plotloop8x24_y0_1:
   2.316          lda ($70),y
   2.317 +        eor ($72),y
   2.318          sta ($72),y
   2.319          dey
   2.320          cpy #16
   2.321 @@ -615,6 +617,7 @@
   2.322  
   2.323      plotloop8x24_y0_2:
   2.324          lda ($70),y
   2.325 +        eor ($72),y
   2.326          sta ($72),y
   2.327          dey
   2.328          cpy #32
   2.329 @@ -647,6 +650,7 @@
   2.330  
   2.331          plotloop8x24_y1_0:
   2.332              lda ($70),y
   2.333 +            eor ($72),y
   2.334              sta ($72),y
   2.335              dey
   2.336              bpl plotloop8x24_y1_0
   2.337 @@ -656,6 +660,7 @@
   2.338  
   2.339          plotloop8x24_y1_1:
   2.340              lda ($70),y
   2.341 +            eor ($72),y
   2.342              sta ($72),y
   2.343              dey
   2.344              cpy #8
   2.345 @@ -682,6 +687,7 @@
   2.346  
   2.347          plotloop8x24_y1_2:
   2.348              lda ($70),y
   2.349 +            eor ($72),y
   2.350              sta ($72),y
   2.351              dey
   2.352              bpl plotloop8x24_y1_2
   2.353 @@ -691,6 +697,7 @@
   2.354  
   2.355          plotloop8x24_y1_3:
   2.356              lda ($70),y
   2.357 +            eor ($72),y
   2.358              sta ($72),y
   2.359              dey
   2.360              cpy #8
   2.361 @@ -805,107 +812,149 @@
   2.362  player_direction_chars_low: .byte $00,$30,$60,$90,$c0,$f0,$20,$50
   2.363  player_direction_chars_high: .byte $34,$34,$34,$34,$34,$34,$35,$35
   2.364  
   2.365 +screen_rows_low: .byte $00,$c0,$80,$40,$00,$c0,$80,$40,$00,$c0
   2.366 +screen_rows_high: .byte $58,$5b,$5f,$63,$67,$6a,$6e,$72,$76,$79
   2.367 +screen_subrows_low: .byte $00,$04,$40,$44,$80,$84
   2.368 +screen_subrows_high: .byte $00,$00,$01,$01,$02,$02
   2.369 +
   2.370 +screen_columns_low: .byte $00,$20,$40,$60,$80,$a0,$c0,$e0,$00,$20
   2.371 +screen_columns_high: .byte $00,$00,$00,$00,$00,$00,$00,$00,$01,$01
   2.372 +screen_subcolumns_low: .byte $00,$08,$10,$18
   2.373 +
   2.374  plot_characters:
   2.375  
   2.376 -    lda $3300
   2.377 -    cmp #1
   2.378 -    bne plot_characters_loop
   2.379 -    clc
   2.380 +    lda #$00
   2.381 +    sta $74
   2.382 +    lda #$33
   2.383 +    sta $75
   2.384  
   2.385 -    ; Use lookup tables to load the offsets into the sprite.
   2.386 +    ldy #0
   2.387 +    plot_characters_loop:
   2.388  
   2.389 -    lda $3301   ; direction
   2.390 -    tax
   2.391 -    lda player_direction_chars_low,x
   2.392 -    sta $70
   2.393 -    lda player_direction_chars_high,x
   2.394 -    sta $71
   2.395 +        lda ($74),y
   2.396 +        cmp #1
   2.397 +        bne plot_characters_next
   2.398  
   2.399 -    ; Load the screen address.
   2.400 +        ; Use lookup tables to load the offsets into the sprite.
   2.401  
   2.402 -    lda $3304
   2.403 -    sta $72
   2.404 -    lda $3305
   2.405 -    sta $73
   2.406 +        ; Direction
   2.407 +        iny
   2.408 +        lda ($74),y
   2.409 +        tax
   2.410 +        lda player_direction_chars_low,x
   2.411 +        sta $70
   2.412 +        lda player_direction_chars_high,x
   2.413 +        sta $71
   2.414  
   2.415 -    ; Use the dy value to determine which plotting routine to use.
   2.416 +        ; y
   2.417 +        iny
   2.418 +        lda ($74),y
   2.419 +        tax
   2.420 +        lda screen_rows_low,x
   2.421 +        sta $72
   2.422 +        lda screen_rows_high,x
   2.423 +        sta $73
   2.424 +        clc
   2.425  
   2.426 -    lda $3307
   2.427 -    and #1
   2.428 -    bne plot_characters_plot_player1
   2.429 +        ; dy
   2.430 +        iny
   2.431 +        lda ($74),y
   2.432 +        tax
   2.433 +        lda screen_subrows_low,x
   2.434 +        adc $72
   2.435 +        sta $72
   2.436 +        lda screen_subrows_high,x
   2.437 +        adc $73
   2.438 +        sta $73
   2.439 +        clc
   2.440  
   2.441 -    jsr plot8x24_y0
   2.442 -    jmp plot_characters_array
   2.443 +        ; x
   2.444 +        iny
   2.445 +        lda ($74),y
   2.446 +        tax
   2.447 +        lda screen_columns_low,x
   2.448 +        adc $72
   2.449 +        sta $72
   2.450 +        lda screen_columns_high,x
   2.451 +        adc $73
   2.452 +        sta $73
   2.453 +        clc
   2.454  
   2.455 -plot_characters_plot_player1:
   2.456 -    clc
   2.457 -    jsr plot8x24_y1
   2.458 +        ; dx
   2.459 +        iny
   2.460 +        lda ($74),y
   2.461 +        tax
   2.462 +        lda screen_subcolumns_low,x
   2.463 +        adc $72
   2.464 +        sta $72
   2.465 +        clc
   2.466  
   2.467 -plot_characters_array:
   2.468 -    ldx #6
   2.469 +        ; Use the dy value to determine which plotting routine to use.
   2.470  
   2.471 -    plot_characters_loop:
   2.472 -        lda $3300,x
   2.473 -        txa
   2.474 +        iny
   2.475 +        lda ($74),y
   2.476 +        and #1
   2.477 +        bne plot_characters_plot_player1
   2.478 +
   2.479 +        jsr plot8x24_y0
   2.480 +        jmp plot_characters_exit
   2.481 +
   2.482 +        plot_characters_plot_player1:
   2.483          clc
   2.484 -        adc #6
   2.485 -        cmp #234
   2.486 -        tax
   2.487 -        bne plot_characters_loop
   2.488 +        jsr plot8x24_y1
   2.489  
   2.490 -    rts
   2.491 +        plot_characters_next:
   2.492 +        clc
   2.493  
   2.494 -room_row_offsets_low: .byte $9c,$a6,$b0,$ba,$c4,$ce,$d8,$e2,$ec,$f6
   2.495 +        ; Examine the next character.
   2.496  
   2.497 -move_player_left:
   2.498 +        iny
   2.499 +        bcc plot_characters_loop
   2.500  
   2.501 -    ; Decrement dx and subtract 8 from the screen address.
   2.502 -
   2.503 -    lda $3301
   2.504 -    and #254    ; remove direction information
   2.505 -    eor #1      ; toggle animation flag
   2.506 -    sta $3301
   2.507 -    lda #0      ; direction = 0
   2.508 -    sta $3301
   2.509 -
   2.510 -    dec $3306
   2.511 -    bpl move_player_left_not_underflow
   2.512 -    lda #3
   2.513 -    sta $3306
   2.514 -
   2.515 -move_player_left_not_underflow:
   2.516 -    sec
   2.517 -    lda $3304   ; screen position -= 8
   2.518 -    sbc #8
   2.519 -    sta $3304
   2.520 +    plot_characters_exit:
   2.521      clc
   2.522      rts
   2.523  
   2.524 +; Note that the room offsets reflect that the room is 
   2.525 +room_row_offsets_low: .byte $9c,$a6,$b0,$ba,$c4,$ce,$d8,$e2,$ec,$f6
   2.526 +
   2.527 +animate_player_left:
   2.528 +
   2.529 +    ; Set the direction and toggle the animation bit.
   2.530 +
   2.531 +    lda $3301
   2.532 +    and #1      ; remove direction information (result is 0)
   2.533 +    eor #1      ; toggle animation flag
   2.534 +    sta $3301
   2.535 +    rts
   2.536 +
   2.537  move_player:
   2.538 -    jsr key_input
   2.539 -    cmp #1
   2.540 +
   2.541 +    ldx #158            ; handle left key
   2.542 +    jsr check_key
   2.543 +    cpy #255
   2.544      bne move_player_not_left_key
   2.545  
   2.546      ; Handle the left key.
   2.547  
   2.548 -    lda $3306           ; read dx
   2.549 +    lda $3305           ; read dx
   2.550      cmp #0
   2.551      beq move_player_check_x
   2.552  
   2.553 -    jmp move_player_left    ; optimise rts
   2.554 +    dec $3305
   2.555 +    clc
   2.556 +    jmp animate_player_left ; optimise away the rts
   2.557 +    
   2.558 +    move_player_check_x:    ; Check the x offset.
   2.559  
   2.560 -move_player_check_x:
   2.561 -
   2.562 -    ; Check the x offset.
   2.563 -
   2.564 -    lda $3302
   2.565 +    lda $3304
   2.566      cmp #0
   2.567      beq move_player_leave_room_left
   2.568  
   2.569      sec
   2.570 -    sbc #1                  ; dx = dx - 1
   2.571 +    sbc #1                  ; x - 1
   2.572      tay
   2.573 -    lda $3303                   ; load the y offset
   2.574 +    lda $3302                   ; load the y offset
   2.575      tax                         ; as an index
   2.576      lda room_row_offsets_low,x  ; read the address of the row
   2.577      sta $70
   2.578 @@ -916,13 +965,25 @@
   2.579      cmp #0
   2.580      bne move_player_not_left_key
   2.581  
   2.582 +    lda $3303               ; dy
   2.583 +    cmp #0
   2.584 +    bne move_player_allow_left
   2.585 +    lda $70
   2.586 +    adc #10
   2.587 +    lda ($70),y             ; load the tile below and to the left
   2.588 +
   2.589 +    cmp #0
   2.590 +    bne move_player_not_left_key
   2.591 +
   2.592 +    move_player_allow_left:
   2.593      tya
   2.594 -    sta $3302               ; store the new room x offset
   2.595 +    sta $3304               ; store the new room x offset
   2.596      lda #3
   2.597 -    sta $3306               ; dx = 3
   2.598 -    jmp move_player_left    ; optimise rts
   2.599 +    sta $3305               ; dx = 3
   2.600 +    clc
   2.601 +    jmp animate_player_left ; optimise away the rts
   2.602  
   2.603 -move_player_leave_room_left:
   2.604 +    move_player_leave_room_left:
   2.605      sec
   2.606      lda $33f3
   2.607      sbc #1
   2.608 @@ -932,22 +993,17 @@
   2.609      ; Set the player's position on the right of the screen.
   2.610  
   2.611      lda #9      ; x = 9
   2.612 -    sta $3302
   2.613 +    sta $3304
   2.614      lda #2      ; dx = 2
   2.615 -    sta $3306
   2.616 +    sta $3305
   2.617  
   2.618 -    lda $3304
   2.619 -    adc #$30
   2.620 -    sta $3304
   2.621 -    lda $3305
   2.622 -    adc #0
   2.623 -    sta $3305
   2.624 -    
   2.625 -    sec
   2.626 +    sec                     ; indicate to the calling routine that the player
   2.627 +    jsr animate_player_left ; has left the room
   2.628      rts
   2.629  
   2.630 -not_left_room:
   2.631 -move_player_not_left_key:
   2.632 +    move_player_not_left_key:
   2.633 +
   2.634 +    move_player_not_up_key:
   2.635      clc
   2.636      rts
   2.637  
   2.638 @@ -1073,20 +1129,16 @@
   2.639  
   2.640      lda #1      ; player
   2.641      sta $3300
   2.642 -    lda #3      ; down
   2.643 +    lda #6      ; down (first frame)
   2.644      sta $3301
   2.645 +    lda #5      ; y=5
   2.646 +    sta $3302
   2.647 +    lda #0      ; dy=0
   2.648 +    sta $3303
   2.649      lda #5      ; x=5
   2.650 -    sta $3302
   2.651 -    lda #5      ; y=5
   2.652 -    sta $3303
   2.653 -    lda #$60    ; centre of the screen
   2.654      sta $3304
   2.655 -    lda #$6b
   2.656 +    lda #0      ; dx=0
   2.657      sta $3305
   2.658 -    lda #0      ; dx=0
   2.659 -    sta $3306
   2.660 -    lda #0      ; dy=0
   2.661 -    sta $3307
   2.662      rts
   2.663  
   2.664  main:
   2.665 @@ -1110,11 +1162,21 @@
   2.666              lda $33f3
   2.667              sta $79
   2.668              jsr plot_room
   2.669 +            jsr plot_characters
   2.670  
   2.671              room_loop:
   2.672 -                jsr plot_characters
   2.673 +                lda #19
   2.674 +                jsr $fff4
   2.675 +                jsr plot_characters ; unplot
   2.676                  jsr move_player
   2.677                  bcs after_room_loop
   2.678 +
   2.679 +                jsr plot_characters ; plot
   2.680 +                ldx #157
   2.681 +                jsr check_key
   2.682 +                cpy #255
   2.683 +                beq exit
   2.684 +                clc
   2.685                  jmp room_loop
   2.686  
   2.687          after_room_loop:
   2.688 @@ -1122,4 +1184,7 @@
   2.689              jmp game_loop
   2.690  
   2.691          jmp main_loop
   2.692 +
   2.693 +    exit:
   2.694 +    clc
   2.695      rts