junglejourney
view mapcode.oph @ 200:2e43c7e90f42
Made some visual fixes.
| author | David Boddie <david@boddie.org.uk> |
|---|---|
| date | Sun Oct 02 21:04:54 2011 +0200 |
| parents | aa9f05624182 |
| children | 72baa6318192 |
line source
1 ; Copyright (C) 2011 David Boddie <david@boddie.org.uk>
2 ;
3 ; This program is free software: you can redistribute it and/or modify
4 ; it under the terms of the GNU General Public License as published by
5 ; the Free Software Foundation, either version 3 of the License, or
6 ; (at your option) any later version.
7 ;
8 ; This program is distributed in the hope that it will be useful,
9 ; but WITHOUT ANY WARRANTY; without even the implied warranty of
10 ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 ; GNU General Public License for more details.
12 ;
13 ; You should have received a copy of the GNU General Public License
14 ; along with this program. If not, see <http://www.gnu.org/licenses/>.
16 .org $1e00
17 jmp main
19 seeds: .byte 100, 239, 183, 144 ; $ef, $b7, $90, $d6, $89
20 start_rooms_x: .byte 5, 3, 5, 10
21 start_rooms_y: .byte 5, 8, 1, 8
22 exit_rooms_x: .byte 7, 9, 3, 0
23 exit_rooms_y: .byte 0, 0, 9, 10
25 ; These values need to be kept in sync - the room numbers must match their
26 ; positions in the room array.
27 key_rooms_x: .byte 1, 5, 10, 1
28 key_rooms_y: .byte 0, 2, 6, 4
29 key_rooms: .byte 1, 27, 76, 45 ; ky*11 + kx
31 treasure_table: .byte 6, 5, 7, 1, 1, 5, 2, 7, 6, 2, 1, 7, 1, 7, 8, 7
32 treasure_table_: .byte 0, 7, 6, 7, 7, 7, 5, 0, 6, 3, 7, 7, 5, 7, 5, 0
34 unlimited_values: ; $7c,$7d=first,second
35 ; Add $7c and $7d, store the result in $7d and the original
36 ; $7d value in $7c, returning the sum in the accumulator.
37 lda $7c
38 sta $7b
39 lda $7d
40 sta $7c
41 adc $7b
42 sta $7d
43 clc
44 rts
46 mod9: ; A = value
47 divide_loop:
48 cmp #9
49 bcc after_divide_loop ; bmi should work here, I think, but it doesn't
50 sec
51 sbc #9
52 jmp divide_loop
54 after_divide_loop:
55 clc
56 rts ; A % 9
58 tile_values_map: .byte 0,1,0,0,0,0,2,3
60 next_value: ; no argument
61 jsr unlimited_values
62 lda $7d
63 jsr mod9
64 and #7 ; (next value % 9) & 7
65 tax
66 lda tile_values_map,x
67 sta $7b
68 rts
70 ; Room filling routines, writing to 0x579c to 0x57ff.
72 draw_top_line: ; $76=tile number for exit/wall
73 ldx #9
74 lda #2
76 draw_top_line_loop0:
77 sta $579c,x
78 dex
79 bpl draw_top_line_loop0
81 ldx #3 ; draw the exit or wall
82 lda $76
83 draw_top_line_loop1:
84 sta $579f,x
85 dex
86 bpl draw_top_line_loop1
87 clc
88 rts
90 draw_left_line: ; $77=tile number for exit/wall
91 ldx #90
92 draw_left_line_loop0:
93 lda #2
94 sta $579c,x
95 txa
96 sec
97 sbc #10
98 tax
99 bpl draw_left_line_loop0
101 ldx #30
102 draw_left_line_loop1:
103 lda $77
104 sta $57ba,x
105 txa
106 sec
107 sbc #10
108 tax
109 bpl draw_left_line_loop1
110 clc
111 rts
113 draw_bottom_line: ; $76=tile number for exit/wall
114 ldx #9
115 lda #2
116 draw_bottom_line_loop0:
117 sta $57f6,x
118 dex
119 bpl draw_bottom_line_loop0
121 ldx #3
122 lda $76
123 draw_bottom_line_loop1:
124 sta $57f9,x
125 dex
126 bpl draw_bottom_line_loop1
127 clc
128 rts
130 draw_right_line: ; $77=tile number for exit/wall
131 ldx #99
132 draw_right_line_loop0:
133 lda #2
134 sta $579c,x
135 txa
136 sec
137 sbc #10
138 tax
139 bpl draw_right_line_loop0
141 ldx #30
142 draw_right_line_loop1:
143 lda $77
144 sta $57c3,x
145 txa
146 sec
147 sbc #10
148 tax
149 bpl draw_right_line_loop1
150 clc
151 rts
153 make_empty_room:
155 ldx #99
156 make_empty_room_loop:
157 lda #0
158 sta $579c,x
159 dex
160 bpl make_empty_room_loop
162 rts
164 make_room: ; $78,$79=i,j
166 ; Fills the room array at 579c with values.
167 ; Tiles 0,1,2,3 are map tiles that will be shown by the plot_tile routine.
168 ; Other tiles are plotted separately:
169 ; 4 = exit
170 ; 5 = final exit
171 ; 6 = weapon (bits 3,4 are type)
172 ; 7 = treasure (bits 3,4 are type)
174 ; Fill the room with empty space.
176 jsr make_empty_room
178 ; Determine if there is a top exit.
180 lda #0
181 sta $76
183 lda $78 ; i == 0
184 cmp #0
185 bne not_top_screen
186 lda #2
187 sta $76
188 jmp do_top_exit
190 not_top_screen:
191 clc
193 lda $78
194 and #7 ; i & 7
195 sta $70 ; temporary result
196 lda $79
197 and #7 ; j & 7
198 cmp $70
199 beq do_top_exit
200 clc
202 lda $78
203 eor $79 ; i ^ j
204 adc $78 ; + i
205 clc
206 cmp $79 ; (i ^ j) + i == j
207 bne do_top_exit
208 lda #2
209 sta $76 ; top exit
211 do_top_exit:
212 jsr draw_top_line
214 ; Determine if there is a left exit.
215 lda #0
216 sta $77
218 lda $79
219 cmp #0
220 bne not_left_screen
221 lda #2
222 sta $77
223 jmp do_left_exit
225 not_left_screen:
226 clc
228 lda $78
229 and #3 ; i & 3
230 sta $70 ; temporary result
231 lda $79
232 and #3 ; j & 3
233 cmp $70
234 beq do_left_exit
235 clc
237 lda $78
238 ora $79 ; i | j
239 eor $79 ; ^ j
240 cmp $78 ; (i | j) ^ j == i
241 bne do_left_exit
242 lda #2
243 sta $77 ; left exit
245 do_left_exit:
246 jsr draw_left_line
248 ; Determine if there is a right exit.
249 lda #0
250 sta $77
252 lda $79
253 cmp #10
254 bne not_right_screen
255 lda #2
256 sta $77
257 jmp do_right_exit
259 not_right_screen:
260 clc
262 lda $78
263 and #3 ; i & 3
264 sta $70 ; temporary result
265 lda $79
266 adc #1
267 and #3 ; j & 3
268 cmp $70
269 beq do_right_exit
270 clc
272 lda $79
273 adc #1
274 sta $70
276 lda $78
277 ora $70 ; i | j
278 eor $70 ; ^ j
279 cmp $78 ; (i | j) ^ j == i
280 bne do_right_exit
281 lda #2
282 sta $77 ; right exit
284 do_right_exit:
285 jsr draw_right_line
287 ; Determine if there is a bottom exit.
288 lda #0
289 sta $76
291 lda $78
292 cmp #10
293 bne not_bottom_screen
294 lda #2
295 sta $76
296 jmp do_bottom_exit
298 not_bottom_screen:
299 clc
301 lda $78
302 adc #1
303 and #7 ; i & 7
304 sta $70 ; temporary result
305 lda $79
306 and #7 ; j & 7
307 cmp $70
308 beq do_bottom_exit
309 clc
311 lda $78
312 adc #1
313 sta $70
315 eor $79 ; i ^ j
316 adc $70 ; + i
317 cmp $79 ; (i ^ j) + i == j
318 bne do_bottom_exit
319 lda #2
320 sta $76 ; bottom exit
322 do_bottom_exit:
323 jsr draw_bottom_line
325 ; Add the final exit.
327 lda $578a
328 cmp #3
329 bmi make_room_no_final_exit
331 lda $78
332 cmp #0
333 bne make_room_no_final_exit
335 lda $79
336 cmp #2
337 bne make_room_no_final_exit
339 lda #6
340 sta $57a0
341 lda #7
342 sta $57a1
344 make_room_no_final_exit:
346 ; Make sure that the starting, exit, key rooms are empty.
348 ldx $578a ; level number
349 lda start_rooms_y,x
350 cmp $78
351 bne make_room_not_starting_room
352 lda start_rooms_x,x
353 cmp $79
354 bne make_room_not_starting_room
356 lda #3
357 sta $70
358 jmp add_room_decoration ; optimise away the rts
360 make_room_not_starting_room:
362 lda exit_rooms_y,x
363 cmp $78
364 bne make_room_not_exit_room
365 lda exit_rooms_x,x
366 cmp $79
367 bne make_room_not_exit_room
369 ; Add an exit to the room.
370 lda $78
371 eor $79
372 and #15
373 tax
374 lda exit_room_offsets,x
375 tax
376 lda $5780
377 and #1
378 beq exit_not_open
380 lda #5
381 sta $579c,x
382 jmp exit_decoration
384 exit_not_open:
385 clc
386 lda #4
387 sta $579c,x
389 exit_decoration:
390 lda #3
391 sta $70
392 jmp add_room_decoration ; optimise away the rts
394 make_room_not_exit_room:
396 lda key_rooms_y,x
397 cmp $78
398 bne make_room_not_key_room
399 lda key_rooms_x,x
400 cmp $79
401 bne make_room_not_key_room
403 lda #1
404 sta $70
405 jmp add_room_decoration ; optimise away the rts
407 make_room_not_key_room:
408 clc
410 ; Fill in the room details.
412 lda $79
413 sta $7c
414 sec
415 ldx $578a
416 lda seeds,x
417 sbc $78
418 sec
419 sta $7d
420 clc
422 ; Discard the first ten values.
424 ldy #10
425 make_room_loop0:
426 jsr unlimited_values
427 dey
428 bne make_room_loop0
430 ; Fill the room array with values.
432 lda #$a7
433 sta $70
434 lda #$57
435 sta $71
437 ldy #0
438 make_room_loop1:
440 jsr next_value
441 sta ($70),y
442 iny
443 cpy #8
444 bne make_room_loop1 ; continue the same row
446 lda $70
447 cmp #$ed
448 beq make_room_loop1_exit ; exit after the last row
450 adc #10
451 sta $70
452 ldy #0 ; reset the row counter
453 jmp make_room_loop1
455 make_room_loop1_exit:
456 rts
458 decoration_offsets: .byte 11,18,81,88
460 add_room_decoration:
462 lda #$9c
463 sta $8e
464 lda #$57
465 sta $8f
467 ldx #3
468 add_room_decoration_loop:
470 lda decoration_offsets,x
471 tay
472 lda $70
473 sta ($8e),y
474 dex
475 bpl add_room_decoration_loop
477 clc
478 rts
480 exit_room_offsets: .byte 35,66,63,56,34,44,64,33,36,55,65,53,45,46,54,43
481 treasure_x: .byte 3, 2, 4, 8, 2, 5, 4, 1, 3, 8, 6, 5, 7, 1, 7, 6
482 treasure_y: .byte 1, 3, 7, 7, 2, 3, 6, 1, 4, 6, 8, 5, 5, 4, 8, 2
484 eleven_times_table: .byte 0, 11, 22, 33, 44, 55, 66, 77, 88, 99, 110
486 add_treasure: ; $78,$79 = i,j
488 lda $78
489 tax
490 lda eleven_times_table,x
491 adc $79
492 tax
494 lda $5200,x
495 ora #$80
496 sta $5200,x ; set the top bit (room visited)
497 and #$7f ; mask off the top bit to obtain the item number + 1
498 cmp #0
499 beq add_treasure_exit
501 sec
502 sbc #1
503 sta $528d ; store weapon/treasure type
504 clc
506 lda $78
507 eor $79
508 adc $528d
509 and #15
510 sta $70
512 lda #15
513 sta $8c
514 ldy #0
515 add_treasure_loop:
517 clc
519 ldx $70
520 lda treasure_y,x ; y
521 sta $8d
522 tax
523 lda room_row_offsets_low,x
524 sta $80
526 ldx $70
527 lda treasure_x,x ; x
528 sta $8e
529 adc $80
530 sta $80
532 lda #$57
533 adc #0
534 sta $81
535 clc
537 lda ($80),y ; tile
538 cmp #0
539 bne add_treasure_loop_next
541 lda #4 ; type (weapon/treasure)
542 sta $528c
543 lda $8d ; y
544 sta $528e
545 lda #1 ; dy
546 sta $528f
547 lda $8e ; x
548 sta $5290
549 lda #0 ; dx
550 sta $5291
552 lda #$8c
553 sta $74
554 lda #$52
555 sta $75
556 jmp plot_character ; optimise away the rts
558 add_treasure_loop_next:
559 dec $8c
560 bmi add_treasure_exit
562 dec $70
563 bpl add_treasure_loop
565 lda #15
566 sta $70
567 jmp add_treasure_loop
569 add_treasure_exit:
570 clc
571 rts
573 create_enemy_positions:
575 lda #31 ; counter
576 sta $7e
578 lda #1 ; x
579 sta $70
581 lda #1 ; y
582 sta $71
584 lda #$a7
585 sta $72
586 lda #$57
587 sta $73
589 ldx #15 ; offset into position areas
590 ldy #0
592 create_enemy_positions_loop:
594 jsr unlimited_values
595 and #7
596 sta $80 ; store temporarily
598 lda $72
599 adc $80
600 sta $72 ; update the offset into the room data
601 clc
603 lda $70
604 adc $80 ; update x
605 cmp #10
606 bpl create_enemy_positions_next_row
608 sta $70 ; store x
609 jmp create_enemy_positions_check_tile
611 create_enemy_positions_next_row:
613 sec
614 sbc #10
615 sta $70 ; store the x position on the next row
616 clc
618 lda $71
619 adc #1 ; update the y position
620 cmp #10
621 bpl create_enemy_positions_to_top
623 sta $71 ; store the y position for the next row
624 jmp create_enemy_positions_check_tile
626 create_enemy_positions_to_top:
628 lda #1 ; reset the x, y and offset values
629 sta $70
630 sta $71
631 lda #$a7
632 sta $72
634 create_enemy_positions_check_tile:
636 lda ($72),y
637 cmp #0
638 bne create_enemy_positions_next
640 lda $70
641 sta $0ee0,x ; store the x value
643 lda $71
644 sta $0ef0,x ; store the y value
646 dex
647 bmi create_enemy_positions_exit
649 create_enemy_positions_next:
650 clc
651 dec $7e
652 bpl create_enemy_positions_loop
654 ; The position areas were not filled. Write invalid values into the
655 ; first area for the emerge routine to find.
657 lda #0
658 create_enemy_positions_fill_loop:
660 sta $0ee0,x
661 dex
662 bpl create_enemy_positions_fill_loop
664 create_enemy_positions_exit:
665 clc
666 rts
668 plot: ; $70,$71=source address
669 ; $72,$73=destination address
670 ldy #$1f
671 plotloop0:
672 lda ($70),y
673 sta ($72),y
674 dey
675 bpl plotloop0
677 lda $72
678 adc #$20
679 sta $72
680 lda $73
681 adc #$01
682 sta $73 ; next line minus 0x20
683 clc
685 ldy #$3f
686 plotloop1:
687 lda ($70),y
688 sta ($72),y
689 dey
690 cpy #$20
691 bpl plotloop1
693 lda $72
694 adc #$20
695 sta $72
696 lda $73
697 adc #$01
698 sta $73 ; next line minus 0x20
699 clc
701 ldy #$5f
702 plotloop2:
703 lda ($70),y
704 sta ($72),y
705 dey
706 cpy #$40
707 bpl plotloop2
709 sec
710 lda $72
711 sbc #$20
712 sta $72
713 lda $73
714 sbc #$02
715 sta $73 ; back two lines minus 0x20
716 clc
718 rts
722 plot_blank_xy: ; X=y, Y=x
724 lda screen_rows_low,x
725 sta $72
726 lda screen_rows_high,x
727 sta $73
729 tya
730 tax
731 lda screen_columns_low,x
732 adc $72
733 sta $72
734 lda screen_columns_high,x
735 adc $73
736 sta $73
737 clc
738 ; run on into plot_blank
740 plot_blank: ; $72,$73=destination address
742 ldy #$1f
743 lda #0
744 plot_blank_loop0:
745 sta ($72),y
746 dey
747 bpl plot_blank_loop0
749 lda $72
750 adc #$20
751 sta $72
752 lda $73
753 adc #$01
754 sta $73 ; next line minus 0x20
755 clc
757 ldy #$3f
758 lda #0
759 plot_blank_loop1:
760 sta ($72),y
761 dey
762 cpy #$20
763 bpl plot_blank_loop1
765 lda $72
766 adc #$20
767 sta $72
768 lda $73
769 adc #$01
770 sta $73 ; next line minus 0x20
771 clc
773 ldy #$5f
774 lda #0
775 plot_blank_loop2:
776 sta ($72),y
777 dey
778 cpy #$40
779 bpl plot_blank_loop2
781 sec
782 lda $72
783 sbc #$20
784 sta $72
785 lda $73
786 sbc #$02
787 sta $73 ; back two lines minus 0x20
788 clc
790 rts
792 tile_addresses_low: .byte $00, $60, $c0, $00, $60, $c0, $20
793 tile_addresses_high: .byte $54, $54, $54, $50, $50, $50, $51
795 plot_tile: ; $7b=tile number
796 ; 1 = flowers/decoration
797 ; 2 = trees/wall
798 ; 3 = trees
799 ; 4 = exit
800 ; 5 = open exit
801 ; 6 = final exit (left)
802 ; 7 = final exit (right)
803 ; $72,$73=screen position
805 lda $7b
806 cmp #0
807 bne plot_tile_sprite
808 clc
809 jmp plot_blank ; optimise away the rts
811 plot_tile_sprite:
812 clc
813 tax
814 dex
815 lda tile_addresses_low,x
816 sta $70
817 lda tile_addresses_high,x
818 sta $71
820 lda $7b
821 cmp #4
822 bpl plot_not_blank_after_add_loop ; don't adjust the tile for later levels
824 clc
825 lda $578a
826 and #3 ; change the tile set for later levels
827 tax
829 plot_not_blank_add_loop:
831 cpx #2
832 bne plot_not_blank_not_2
833 dex
834 jmp plot_not_blank_not_0
836 plot_not_blank_not_2:
837 beq plot_not_blank_add_loop
838 cpx #0
840 plot_not_blank_not_0:
841 beq plot_not_blank_after_add_loop
842 clc
843 lda $70
844 adc #$20
845 sta $70
846 lda $71
847 adc #$01
848 sta $71
849 dex
850 jmp plot_not_blank_add_loop
852 plot_not_blank_after_add_loop:
853 clc
854 jsr plot
855 rts
857 plot_room: ; $78,$79 = i,j (from $5782,$5783)
858 jsr blank_screen
860 lda $5782
861 sta $78
862 lda $5783
863 sta $79
865 jsr make_room
866 ; Run on into the next piece of code.
868 plot_room_tiles:
870 lda #$80
871 sta $72
872 lda #$5a
873 sta $73 ; $72,$73 = screen position
875 lda #0
876 sta $7a
877 row_loop:
879 lda #9
880 sta $76
882 column_loop:
883 lda $7a
884 tax
885 lda $579c,x
886 sta $7b
887 jsr plot_tile
889 inc $7a
890 lda $76
891 sec
892 sbc #1
893 sta $76
894 clc
895 cmp #0
896 bpl column_loop
898 clc
900 lda $72
901 adc #$80
902 sta $72
903 lda $73
904 adc #$02
905 sta $73
906 clc
907 cmp #$80
908 beq end_rows
910 jmp row_loop
912 end_rows:
913 rts
915 set_room_palette: ; $78=i; $79=j
917 lda #1
918 sta $70
919 lda $78
920 eor $79
921 and #3
922 tax
923 lda room_palettes,x
924 sta $71
925 jsr set_palette
927 jsr set_core_palette
928 rts
930 room_palettes: .byte 1, 6, 5, 7
932 ; Sprite data stored in memory: 00 04 08 0c 10 14 18 1c 20 24 28 2c
934 plot8x24_y0: ; $70,$71=source address
935 ; $72,$73=destination address
937 ldx #2
939 plot8x24_y0_loop:
941 ldy #15
943 plotloop8x24_y0_0:
944 lda ($70),y
945 eor ($72),y
946 sta ($72),y
947 dey
948 bpl plotloop8x24_y0_0
950 dex
951 bmi plot8x24_y0_exit
953 lda $72
954 adc #$40
955 sta $72
956 lda $73
957 adc #$01
958 sta $73
959 clc
961 lda $70
962 adc #16
963 sta $70
964 lda $71
965 adc #0
966 sta $71
967 clc
969 jmp plot8x24_y0_loop
971 plot8x24_y0_exit:
972 clc
973 jmp plot_buffer_loop_next
976 plot8x8_y1: ; $70,$71=source address
977 ; $72,$73=destination address
978 lda #2
979 sta $7e
980 lda #10
981 sta $7f
983 lda #0 ; plotting 1 8x8 piece
984 sta $8a
986 jmp plot8x24_y123 ; optimise away the rts
988 plot8x24_y1: ; $70,$71=source address
989 ; $72,$73=destination address
990 lda #2
991 sta $7e
992 lda #10
993 sta $7f
995 lda #2 ; plotting 3 8x8 pieces
996 sta $8a
998 jmp plot8x24_y123 ; optimise away the rts
1000 plot8x8_y2: ; $70,$71=source address
1001 ; $72,$73=destination address
1002 lda #4
1003 sta $7e
1004 lda #12
1005 sta $7f
1007 lda #0 ; plotting 1 8x8 piece
1008 sta $8a
1010 jmp plot8x24_y123 ; optimise away the rts
1012 plot8x24_y2: ; $70,$71=source address
1013 ; $72,$73=destination address
1014 lda #4
1015 sta $7e
1016 lda #12
1017 sta $7f
1019 lda #2 ; plotting 3 8x8 pieces
1020 sta $8a
1022 jmp plot8x24_y123 ; optimise away the rts
1024 plot8x8_y3: ; $70,$71=source address
1025 ; $72,$73=destination address
1026 lda #6
1027 sta $7e
1028 lda #14
1029 sta $7f
1031 lda #0 ; plotting 1 8x8 piece
1032 sta $8a
1034 jmp plot8x24_y123 ; optimise away the rts
1036 plot8x24_y3: ; $70,$71=source address
1037 ; $72,$73=destination address
1038 lda #6
1039 sta $7e
1040 lda #14
1041 sta $7f
1043 lda #2 ; plotting 3 8x8 pieces
1044 sta $8a
1046 ; Run on into the next routine.
1048 plot8x24_y123: ; $70,$71=source address
1049 ; $72,$73=destination address
1050 ; $7e=offset into source data for first column
1051 ; $7f=offset into source data for second column
1053 plot8x24_y123_loop:
1055 ldx #0
1056 plot8x24_y123_upper_loop_outer:
1058 ldy $7e,x
1059 lda plot_upper_offsets,x
1060 sta $89
1062 plot8x24_y123_upper_loop_inner: ; plot the first column until
1063 dey ; we reach the start
1064 cpy $89
1065 bmi plot8x24_y123_upper_loop_inner_endloop
1066 lda ($70),y
1067 eor ($72),y
1068 sta ($72),y
1069 jmp plot8x24_y123_upper_loop_inner
1071 plot8x24_y123_upper_loop_inner_endloop:
1072 clc
1074 inx
1075 cpx #2
1076 bne plot8x24_y123_upper_loop_outer
1078 clc
1079 lda $72 ; move the destination pointer to refer to the next line
1080 adc #$38
1081 sta $72
1082 lda $73
1083 adc #$01
1084 sta $73
1085 clc
1087 ldx #0
1088 plot8x24_y123_lower_loop_outer:
1090 lda plot_lower_offsets,x
1091 tay
1092 lda $7e,x
1093 sta $89
1095 plot8x24_y123_lower_loop_inner: ; plot until we reach the initial
1096 lda ($70),y ; offset for the column
1097 eor ($72),y
1098 sta ($72),y
1099 dey
1100 cpy $89
1101 bpl plot8x24_y123_lower_loop_inner
1103 inx
1104 cpx #2
1105 bne plot8x24_y123_lower_loop_outer
1107 dec $8a
1108 bmi plot8x24_y123_exit
1110 clc
1111 lda $70 ; update the source pointer to refer to the next piece
1112 adc #16 ; of sprite data
1113 sta $70
1114 lda $71
1115 adc #0
1116 sta $71
1117 clc
1119 lda $72 ; update the destination pointer to point to the next
1120 adc #8 ; space
1121 sta $72
1122 lda $73
1123 adc #0
1124 sta $73
1125 clc
1127 jmp plot8x24_y123_loop
1129 plot8x24_y123_exit:
1130 clc
1131 jmp plot_buffer_loop_next
1133 plot16x16_y0: ; $70,$71=source address
1134 ; $72,$73=destination address
1135 ldy #31
1137 plotloop16x16_y0_0:
1138 lda ($70),y
1139 eor ($72),y
1140 sta ($72),y
1141 dey
1142 bpl plotloop16x16_y0_0
1143 clc
1145 lda $72
1146 adc #$20
1147 sta $72
1148 lda $73
1149 adc #$01
1150 sta $73 ; 0x140 - 32
1151 clc
1153 ldy #63
1155 plotloop16x16_y0_1:
1156 lda ($70),y
1157 eor ($72),y
1158 sta ($72),y
1159 dey
1160 cpy #32
1161 bpl plotloop16x16_y0_1
1162 clc
1164 jmp plot_buffer_loop_next
1166 ; Sprite data stored in memory: 00 04 08 0c 10 14 18 1c 20 24 28 2c 30 34 38 3c
1168 plot16x16_y1: ; $70,$71=source address
1169 ; $72,$73=destination address
1171 lda #2
1172 sta $7e
1173 lda #10
1174 sta $7f
1175 lda #18
1176 sta $80
1177 lda #26
1178 sta $81
1179 jmp plot16x16_y123 ; optimise away the rts
1181 plot16x16_y2: ; $70,$71=source address
1182 ; $72,$73=destination address
1184 lda #4
1185 sta $7e
1186 lda #12
1187 sta $7f
1188 lda #20
1189 sta $80
1190 lda #28
1191 sta $81
1192 jmp plot16x16_y123 ; optimise away the rts
1194 plot16x16_y3: ; $70,$71=source address
1195 ; $72,$73=destination address
1197 lda #6
1198 sta $7e
1199 lda #14
1200 sta $7f
1201 lda #22
1202 sta $80
1203 lda #30
1204 sta $81
1205 ; Run on into the next routine.
1207 plot16x16_y123: ; $70,$71=source address
1208 ; $72,$73=destination address
1209 ; $7e=offset into source data for first column
1210 ; $7f=offset into source data for second column
1211 ; $80=offset into source data for third column
1212 ; $81=offset into source data for fourth column
1214 lda #1
1215 sta $8a
1217 plot16x16_y123_loop:
1219 ldx #0
1220 plot16x16_y123_upper_loop_outer:
1222 ldy $7e,x
1223 lda plot_upper_offsets,x
1224 sta $89
1226 plot16x16_y123_upper_loop_inner:
1228 dey
1229 cpy $89
1230 bmi plot16x16_y123_upper_loop_inner_endloop
1231 lda ($70),y
1232 eor ($72),y
1233 sta ($72),y
1234 jmp plot16x16_y123_upper_loop_inner
1236 plot16x16_y123_upper_loop_inner_endloop:
1237 clc
1239 inx
1240 cpx #4
1241 bne plot16x16_y123_upper_loop_outer
1243 clc
1244 lda $72 ; move the destination pointer to refer to the next line
1245 adc #$38
1246 sta $72
1247 lda $73
1248 adc #$01
1249 sta $73
1250 clc
1252 ldx #0
1253 plot16x16_y123_lower_loop_outer:
1255 lda plot_lower_offsets,x
1256 tay
1257 lda $7e,x
1258 sta $89
1260 plot16x16_y123_lower_loop_inner: ; plot until we reach the initial offset
1261 lda ($70),y ; for the column
1262 eor ($72),y
1263 sta ($72),y
1264 dey
1265 cpy $89
1266 bpl plot16x16_y123_lower_loop_inner
1268 inx
1269 cpx #4
1270 bne plot16x16_y123_lower_loop_outer
1272 dec $8a
1273 bmi plot16x16_y123_exit
1275 clc
1276 lda $70 ; update the source pointer to refer to the next piece
1277 adc #32 ; of sprite data
1278 sta $70
1279 lda $71
1280 adc #0
1281 sta $71
1282 clc
1284 lda $72 ; update the destination pointer to point to the next
1285 adc #8 ; space
1286 sta $72
1287 lda $73
1288 adc #0
1289 sta $73
1290 clc
1292 jmp plot16x16_y123_loop
1294 plot16x16_y123_exit:
1295 clc
1296 jmp plot_buffer_loop_next
1298 plot_upper_offsets: .byte 0, 8, 16, 24
1299 plot_lower_offsets: .byte 7, 15, 23, 31
1301 plot8x8_y0: ; $70,$71=source address
1302 ; $72,$73=destination address
1303 ldy #15
1305 plotloop8x8_y0_0:
1306 lda ($70),y
1307 eor ($72),y
1308 sta ($72),y
1309 dey
1310 bpl plotloop8x8_y0_0
1311 clc
1313 jmp plot_buffer_loop_next
1316 check_key: ; x=key code
1317 lda #129 ; returns y=255 or 0
1318 ldy #255
1319 jsr $fff4
1320 rts
1322 player_direction_chars_low: .byte $00,$30,$60,$90,$c0,$f0,$20,$50, $80,$b0,$e0,$10
1323 player_direction_chars_high: .byte $3f,$3f,$3f,$3f,$3f,$3f,$40,$40, $40,$40,$40,$41
1325 screen_rows_low: .byte $80,$40,$00,$c0,$80,$40,$00,$c0,$80,$40
1326 screen_rows_high: .byte $5a,$5e,$62,$65,$69,$6d,$71,$74,$78,$7c
1327 screen_subrows_low: .byte $00,$06,$44,$82
1328 screen_subrows_high: .byte $00,$00,$01,$02
1330 screen_columns_low: .byte $00,$20,$40,$60,$80,$a0,$c0,$e0,$00,$20
1331 screen_columns_high: .byte $00,$00,$00,$00,$00,$00,$00,$00,$01,$01
1332 screen_subcolumns_low: .byte $00,$08,$10,$18
1334 enemy_direction_chars_low: .byte $c0,$00,$40,$80,$c0,$00,$40,$80
1335 enemy_direction_chars_high: .byte $41,$42,$42,$42,$42,$43,$43,$43
1337 emerge_explode_chars_low: .byte $c0,$00,$40,$80,$c0,$00,$40,$80
1338 emerge_explode_chars_high: .byte $4b,$4c,$4c,$4c,$4c,$4d,$4d,$4d
1340 item_chars_low: .byte $c0,$00,$40,$80,$c0,$00,$40,$80,$c0
1341 item_chars_high: .byte $4d,$4e,$4e,$4e,$4e,$4f,$4f,$4f,$4f
1343 projectile_chars_low: .byte $40,$50,$60,$70,$80,$90,$a0,$b0
1345 unplot_character: ; $74,$75=character address
1347 lda $82 ; store the unplot buffer address in $78,$79
1348 sta $78
1349 lda $83
1350 sta $79
1351 jsr plot_character_sprite
1352 lda $78
1353 sta $82 ; update the latest space in the unplot buffer
1354 rts
1356 plot_character: ; $74,$75=character address
1358 lda $84 ; store the plot buffer address in $78,$79
1359 sta $78
1360 lda $85
1361 sta $79
1362 jsr plot_character_sprite
1363 lda $78
1364 sta $84 ; update the latest space in the plot buffer
1365 rts
1367 plot_character_sprite: ; $74,$75=character address
1368 ; $78,$79=unplot/plot buffer address
1370 ldy #0
1371 lda ($74),y
1372 cmp #0
1373 bne plot_characters_read_character
1374 jmp plot_characters_next
1376 plot_characters_read_character:
1377 clc
1379 sta $77 ; temporarily store the object type
1381 ; Use lookup tables to load the offsets into the sprite.
1383 ; Direction
1384 iny
1385 lda ($74),y
1386 sta $80 ; temporarily store the direction
1388 ; y
1389 iny
1390 lda ($74),y
1391 tax
1392 lda screen_rows_low,x
1393 sta $72
1394 lda screen_rows_high,x
1395 sta $73
1396 clc
1398 ; dy
1399 iny
1400 lda ($74),y
1401 sta $76
1402 tax
1403 lda screen_subrows_low,x
1404 adc $72
1405 sta $72
1406 lda screen_subrows_high,x
1407 adc $73
1408 sta $73
1409 clc
1411 ; x
1412 iny
1413 lda ($74),y
1414 tax
1415 lda screen_columns_low,x
1416 adc $72
1417 sta $72
1418 lda screen_columns_high,x
1419 adc $73
1420 sta $73
1421 clc
1423 ; dx
1424 iny
1425 lda ($74),y
1426 tax
1427 lda screen_subcolumns_low,x
1428 adc $72
1429 sta $72
1430 clc
1432 lda $77
1433 cmp #1
1434 bne plot_characters_loop_not_player
1436 ; Plot 8x24 sprites (player)
1438 ldx $80
1439 lda player_direction_chars_low,x
1440 sta $70
1441 lda player_direction_chars_high,x
1442 sta $71
1444 ; Use the dy value to determine which plotting routine to use.
1446 ldy #0
1447 ldx $76
1448 lda plot_routine_indices_8x24,x
1450 sta ($78),y
1451 jmp plot_characters_stored
1454 plot_characters_loop_not_player:
1455 cmp #2
1456 bne plot_characters_loop_not_projectile
1458 ; Plot 8x8 sprites (projectiles)
1460 lda $80
1461 and #7
1462 tax
1463 lda projectile_chars_low,x
1464 sta $70
1465 lda #$41
1466 sta $71
1468 ; Use the dy value to determine which plotting routine to use.
1470 ldy #0
1471 ldx $76
1472 lda plot_routine_indices_8x8,x
1474 sta ($78),y
1475 jmp plot_characters_stored
1478 plot_characters_loop_not_projectile:
1479 cmp #3
1480 bne plot_characters_loop_not_explosion
1482 ; Plot 16x16 sprites (emerging, explosions)
1484 ; Select the sprites to use.
1486 lda $80
1487 and #7 ; only keep the bits required to find the correct sprite
1488 clc
1489 tax
1490 lda emerge_explode_chars_low,x
1491 sta $70
1492 lda emerge_explode_chars_high,x
1493 sta $71
1495 jmp plot_characters_16x16
1497 plot_characters_loop_not_explosion:
1498 cmp #4
1499 bne plot_characters_loop_not_item
1501 ; Plot 16x16 sprites (items)
1503 ; Select the sprites to use.
1505 lda $80
1506 and #$0f ; only keep the bits required to find the correct sprite
1507 clc
1508 tax
1509 lda item_chars_low,x
1510 sta $70
1511 lda item_chars_high,x
1512 sta $71
1514 jmp plot_characters_16x16
1516 plot_characters_loop_not_item:
1517 cmp #8
1518 bmi plot_characters_loop_not_enemy
1520 ; Plot 16x16 sprites (enemies)
1522 ; Select the set of sprites to use.
1524 and #$70
1525 lsr
1526 lsr
1527 lsr ; bits 4,5,6 >> 3 -> bits 1,2,3
1528 clc
1529 sta $71 ; 0x00, 0x02, 0x04, 0x06, 0x08
1531 lda $80
1532 and #7 ; keep the animation bits
1533 tax
1534 lda enemy_direction_chars_low,x
1535 sta $70
1536 lda enemy_direction_chars_high,x
1537 adc $71
1538 sta $71
1540 plot_characters_16x16:
1542 ; Use the dy value to determine which plotting routine to use.
1544 ldy #0
1545 ldx $76
1546 lda plot_routine_indices_16x16,x
1548 sta ($78),y
1550 plot_characters_stored:
1552 iny
1553 lda $70
1554 sta ($78),y
1555 iny
1556 lda $71
1557 sta ($78),y
1558 iny
1559 lda $72
1560 sta ($78),y
1561 iny
1562 lda $73
1563 sta ($78),y
1565 clc
1566 lda $78
1567 adc #12
1568 sta $78
1570 plot_characters_loop_not_enemy:
1572 plot_characters_next:
1574 lda #255 ; terminate this stream of entries in the plot buffer
1575 ldy #0
1576 sta ($78),y
1577 clc
1578 rts
1580 plot_routine_indices_8x24: .byte 1, 2, 3, 4
1581 plot_routine_indices_8x8: .byte 5, 6, 7, 8
1582 plot_routine_indices_16x16: .byte 9, 10, 11, 12
1584 reset_plot_buffer:
1585 lda #$06 ; reset the index into the plot buffer
1586 sta $84
1587 lda #$53
1588 sta $85
1590 lda #255 ; terminate the plot list
1591 ldy #0
1592 sta ($84),y
1593 rts
1595 reset_unplot_buffer:
1596 lda #$00 ; reset the index into the plot buffer
1597 sta $82
1598 lda #$53
1599 sta $83
1601 lda #255 ; terminate the unplot list
1602 ldy #0
1603 sta ($82),y
1604 rts
1606 plot_buffer_types_low: .byte <plot_buffer_loop_next
1607 plot_buffer_types_low1: .byte <plot8x24_y0, <plot8x24_y1, <plot8x24_y2, <plot8x24_y3
1608 plot_buffer_types_low2: .byte <plot8x8_y0, <plot8x8_y1, <plot8x8_y2, <plot8x8_y3
1609 plot_buffer_types_low3: .byte <plot16x16_y0, <plot16x16_y1, <plot16x16_y2, <plot16x16_y3
1611 plot_buffer_types_high: .byte >plot_buffer_loop_next
1612 plot_buffer_types_high1: .byte >plot8x24_y0, >plot8x24_y1, >plot8x24_y2, >plot8x24_y3
1613 plot_buffer_types_high2: .byte >plot8x8_y0, >plot8x8_y1, >plot8x8_y2, >plot8x8_y3
1614 plot_buffer_types_high3: .byte >plot16x16_y0, >plot16x16_y1, >plot16x16_y2, >plot16x16_y3
1616 plot_buffer:
1618 lda #$00
1619 sta $84
1620 lda #$53
1621 sta $85
1623 lda #6
1624 sta $88
1626 plot_buffer_loop:
1628 ldy #0
1629 lda ($84),y
1630 cmp #255
1631 beq plot_buffer_loop_skip
1633 clc
1634 tax
1635 lda plot_buffer_types_low,x
1636 sta $86
1637 lda plot_buffer_types_high,x
1638 sta $87
1640 iny
1641 lda ($84),y
1642 sta $70
1644 iny
1645 lda ($84),y
1646 sta $71
1648 iny
1649 lda ($84),y
1650 sta $72
1652 iny
1653 lda ($84),y
1654 sta $73
1656 jmp ($86) ; returns to plot_buffer_loop_next
1658 plot_buffer_loop_skip:
1660 lda $88
1661 cmp #12
1662 beq plot_buffer_exit ; both unplot and plot lists have terminated
1664 lda #12
1665 sta $88
1666 lda $84
1667 adc #6
1668 sta $84
1669 jmp plot_buffer_loop
1671 plot_buffer_loop_next:
1672 clc
1674 lda $84
1675 adc $88
1676 sta $84
1677 jmp plot_buffer_loop
1679 plot_buffer_exit:
1680 clc
1681 rts
1683 room_row_offsets_low: .byte $9c,$a6,$b0,$ba,$c4,$ce,$d8,$e2,$ec,$f6
1685 animate_player_left:
1687 ; Set the direction and toggle the animation bit.
1689 lda $5281
1690 and #1
1691 eor #1 ; toggle animation flag
1692 sta $5281 ; left (directional bits are 0)
1694 jsr plot_character
1695 rts
1697 animate_player_right:
1699 ; Set the direction and toggle the animation bit.
1701 lda $5281
1702 and #1 ; remove direction information (result is 0)
1703 eor #1 ; toggle animation flag
1704 ora #2 ; right
1705 sta $5281
1707 jsr plot_character
1708 rts
1710 animate_player_up:
1712 ; Set the direction and toggle the animation bit.
1714 lda $5281
1715 and #1 ; remove direction information (result is 0)
1716 eor #1 ; toggle animation flag
1717 ora #4 ; up
1718 sta $5281
1720 jsr plot_character
1721 rts
1723 animate_player_down:
1725 ; Set the direction and toggle the animation bit.
1727 lda $5281
1728 and #1 ; remove direction information (result is 0)
1729 eor #1 ; toggle animation flag
1730 ora #6 ; down
1731 sta $5281
1733 jsr plot_character
1734 rts
1736 move_player:
1738 lda $578e
1739 and #1
1740 beq move_player_allowed
1742 clc
1743 rts
1745 move_player_allowed:
1747 lda #$80 ; set up the address of the player character
1748 sta $74
1749 lda #$52
1750 sta $75
1752 ; Handle joystick
1754 lda $577e
1755 cmp #0
1756 beq move_player_handle_left_key
1758 lda #128
1759 ldx #1
1760 jsr $fff4
1761 cpy #112 ; <= -16
1762 bcs move_player_check_joystick_left
1763 jmp move_player_right
1765 move_player_check_joystick_left:
1766 cpy #144 ; >= 16
1767 bcc move_player_handle_joystick_up_down
1768 jmp move_player_left
1770 move_player_handle_joystick_up_down:
1772 lda #128
1773 ldx #2
1774 jsr $fff4
1775 cpy #112 ; <= -16
1776 bcs move_player_check_joystick_up
1777 jmp move_player_down
1779 move_player_check_joystick_up:
1780 cpy #144
1781 bcc move_player_no_joystick_input
1782 jmp move_player_up ; >= 16
1784 move_player_no_joystick_input:
1785 clc
1786 rts
1788 move_player_handle_left_key:
1790 ; Handle the left key.
1792 ldx #158 ; (Z)
1793 jsr check_key
1794 cpy #255
1795 bne move_player_not_left_key
1797 move_player_left:
1799 lda $5285 ; read dx
1800 cmp #0
1801 beq move_player_left_check_x
1803 jsr unplot_character ; unplot the player character
1804 dec $5285
1805 clc
1806 jmp animate_player_left ; optimise away the rts
1808 move_player_left_check_x: ; Check the x offset.
1810 lda $5284
1811 cmp #0
1812 beq move_player_leave_room_left
1814 clc
1815 tay
1816 dey ; x - 1
1817 lda $5282 ; load the y offset
1818 tax ; as an index
1819 lda room_row_offsets_low,x ; read the address of the row
1820 sta $70
1821 lda #$57
1822 sta $71
1823 lda ($70),y ; load the tile to the left
1825 cmp #5 ; check for the open exit or final exit
1826 bmi move_player_not_left_exit1
1827 jmp try_to_exit_level ; optimise away the rts
1829 move_player_not_left_exit1:
1830 cmp #0
1831 bne move_player_not_left_key
1833 lda $5283 ; dy
1834 cmp #0
1835 beq move_player_allow_left
1837 clc
1838 lda $70 ; dy > 0 so we need to check another tile
1839 adc #10
1840 sta $70
1841 lda ($70),y ; load the tile below and to the left
1843 cmp #5 ; check for the open exit or final exit
1844 bmi move_player_not_left_exit2
1845 jmp try_to_exit_level ; optimise away the rts
1847 move_player_not_left_exit2:
1848 cmp #0
1849 bne move_player_not_left_key
1851 move_player_allow_left:
1852 tya
1853 sta $81 ; temporary
1854 jsr unplot_character ; unplot the player character
1855 lda $81
1856 sta $5284 ; store the new room x offset
1857 lda #3
1858 sta $5285 ; dx = 3
1859 clc
1860 jmp animate_player_left ; optimise away the rts
1862 move_player_leave_room_left:
1863 sec
1864 lda $5783
1865 sbc #1
1866 sta $5783
1867 clc
1869 ; Set the player's position on the right of the screen.
1871 ; No need to unplot.
1873 lda #9 ; x = 9
1874 sta $5284
1875 lda #2 ; dx = 2
1876 sta $5285
1878 jsr animate_player_left
1879 sec ; indicate to the calling routine that the player
1880 rts ; has left the room
1882 move_player_not_left_key:
1884 ; Handle the right key.
1886 ldx #189 ; (X)
1887 jsr check_key
1888 cpy #255
1889 beq move_player_right
1890 jmp move_player_not_right_key
1892 move_player_right:
1894 lda $5285 ; read dx
1895 cmp #2
1896 beq move_player_right_check_x
1897 cmp #3
1898 beq move_player_right_tile
1900 jsr unplot_character ; unplot the player character
1901 inc $5285
1902 clc
1903 jmp animate_player_right ; optimise away the rts
1905 move_player_right_check_x: ; Check the x offset.
1907 lda $5284
1908 cmp #9
1909 beq move_player_leave_room_right
1911 clc
1912 tay
1913 iny ; x + 1
1914 lda $5282 ; load the y offset
1915 tax ; as an index
1916 lda room_row_offsets_low,x ; read the address of the row
1917 sta $70
1918 lda #$57
1919 sta $71
1920 lda ($70),y ; load the tile to the right
1922 cmp #5 ; check for the open exit or final exit
1923 bmi move_player_not_right_exit1
1924 jmp try_to_exit_level ; optimise away the rts
1926 move_player_not_right_exit1:
1927 cmp #0
1928 bne move_player_not_right_key
1930 lda $5283 ; dy
1931 cmp #0
1932 beq move_player_allow_right
1934 clc ; dy > 0 so we need to check another tile
1935 lda $70
1936 adc #10
1937 sta $70
1938 lda ($70),y ; load the tile below and to the right
1940 cmp #5 ; check for the open exit or final exit
1941 bmi move_player_not_right_exit2
1942 jmp try_to_exit_level ; optimise away the rts
1944 move_player_not_right_exit2:
1945 cmp #0
1946 bne move_player_not_right_key
1948 move_player_allow_right:
1950 jsr unplot_character ; unplot the player character
1951 inc $5285 ; update dx
1952 clc
1953 jmp animate_player_right ; optimise away the rts
1955 move_player_right_tile:
1957 jsr unplot_character ; unplot the player character
1958 inc $5284 ; store the new room x offset
1959 lda #0
1960 sta $5285 ; dx = 0
1961 clc
1962 jmp animate_player_right ; optimise away the rts
1964 move_player_leave_room_right:
1965 clc
1966 inc $5783
1967 clc
1969 ; Set the player's position on the left of the screen.
1971 ; No need to unplot.
1973 lda #0 ; x = 0
1974 sta $5284
1975 lda #0 ; dx = 0
1976 sta $5285
1978 jsr animate_player_right
1979 sec ; indicate to the calling routine that the
1980 rts ; player has left the room
1982 move_player_not_right_key:
1984 ; Handle the up key.
1986 ldx #183 ; (:)
1987 jsr check_key
1988 cpy #255
1989 bne move_player_not_up_key
1991 move_player_up:
1993 lda $5283 ; read dy
1994 cmp #0
1995 beq move_player_up_check_y
1997 jsr unplot_character ; unplot the player character
1998 dec $5283
1999 clc
2000 jmp animate_player_up ; optimise away the rts
2002 move_player_up_check_y: ; Check the y offset.
2004 lda $5282
2005 cmp #0
2006 beq move_player_leave_room_up
2008 tax ; use the y offset as an index
2009 dex ; y - 1
2010 ldy $5284 ; load the x offset
2011 lda room_row_offsets_low,x ; read the address of the row
2012 sta $70
2013 lda #$57
2014 sta $71
2015 lda ($70),y ; load the tile above
2017 cmp #5 ; check for the open exit or final exit
2018 bmi move_player_not_up_exit1
2019 jmp try_to_exit_level ; optimise away the rts
2021 move_player_not_up_exit1:
2022 cmp #0
2023 bne move_player_not_up_key
2025 lda $5285 ; dx
2026 cmp #3
2027 bmi move_player_allow_up
2029 clc ; dx > 2 so we need to check another tile
2030 iny
2031 lda ($70),y ; load the tile above and to the right
2033 cmp #5 ; check for the open exit or final exit
2034 bmi move_player_not_up_exit2
2035 jmp try_to_exit_level ; optimise away the rts
2037 move_player_not_up_exit2:
2038 cmp #0
2039 bne move_player_not_up_key
2041 move_player_allow_up:
2042 txa
2043 sta $81 ; temporary
2044 jsr unplot_character ; unplot the player character
2045 lda $81
2046 sta $5282 ; store the new room y offset
2047 lda #3
2048 sta $5283 ; dy = 3
2049 clc
2050 jmp animate_player_up ; optimise away the rts
2052 move_player_leave_room_up:
2053 sec
2054 lda $5782
2055 sbc #1
2056 sta $5782
2057 clc
2059 ; Set the player's position on the bottom of the screen.
2061 ; No need to unplot.
2063 lda #9 ; y = 9
2064 sta $5282
2065 lda #0 ; dy = 0
2066 sta $5283
2068 jsr animate_player_up
2069 sec ; indicate to the calling routine that the player
2070 rts ; has left the room
2072 move_player_not_up_key:
2074 ; Handle the down key.
2076 ldx #151 ; (/)
2077 jsr check_key
2078 cpy #255
2079 beq move_player_down
2080 jmp move_player_not_down_key
2082 move_player_down:
2084 lda $5283 ; read dy
2085 cmp #0
2086 beq move_player_down_check_y
2087 cmp #3
2088 beq move_player_down_tile
2090 jsr unplot_character ; unplot the player character
2091 inc $5283 ; 0 <= dy < 3
2092 clc
2093 jmp animate_player_down ; optimise away the rts
2095 move_player_down_check_y: ; Check the y offset.
2097 lda $5282
2098 cmp #9
2099 beq move_player_leave_room_down
2101 clc
2102 tax
2103 inx ; y + 1
2104 ldy $5284 ; load the x offset
2105 lda room_row_offsets_low,x ; read the address of the row
2106 sta $70
2107 lda #$57
2108 sta $71
2109 lda ($70),y ; load the tile below
2111 cmp #5 ; check for the open exit or final exit
2112 bmi move_player_not_down_exit1
2113 jmp try_to_exit_level ; optimise away the rts
2115 move_player_not_down_exit1:
2116 cmp #0
2117 bne move_player_not_down_key
2119 lda $5285 ; dx
2120 cmp #3
2121 bmi move_player_allow_down
2123 clc ; dx > 2 so we need to check another tile
2124 iny
2125 lda ($70),y ; load the tile below and to the right
2127 cmp #5 ; check for the open exit or final exit
2128 bmi move_player_not_down_exit2
2129 jmp try_to_exit_level ; optimise away the rts
2131 move_player_not_down_exit2:
2132 cmp #0
2133 bne move_player_not_down_key
2135 move_player_allow_down:
2137 jsr unplot_character ; unplot the player character
2138 inc $5283 ; update dy
2139 clc
2140 jmp animate_player_down ; optimise away the rts
2142 move_player_down_tile:
2144 jsr unplot_character ; unplot the player character
2145 inc $5282 ; store the new room y offset
2146 lda #0
2147 sta $5283 ; dy = 0
2148 clc
2149 jmp animate_player_down ; optimise away the rts
2151 move_player_leave_room_down:
2152 inc $5782
2153 clc
2155 ; Set the player's position on the top of the screen.
2157 ; No need to unplot.
2159 lda #0 ; y = 0
2160 sta $5282
2161 lda #0 ; dy = 0
2162 sta $5283
2164 jsr animate_player_down
2165 sec ; indicate to the calling routine that the
2166 rts ; player has left the room
2168 move_player_not_down_key:
2169 clc
2170 rts
2172 try_to_exit_level:
2174 cmp #6
2175 bmi just_exit_level
2177 lda $5780 ; set the complete game flag
2178 ora #$02
2179 jmp try_to_exit_level_exit
2181 just_exit_level:
2182 lda $5780 ; set the exit level flag
2183 ora #$80
2185 try_to_exit_level_exit:
2186 sta $5780
2188 lda #$80
2189 sta $74
2190 lda #$52
2191 sta $75
2192 jsr unplot_character ; remove the player sprite
2193 jmp destroy_enemies ; optimise away the rts
2195 check_fire_key:
2197 lda $578d
2198 bne check_fire_key_exit
2200 lda $577e
2201 beq check_fire_key_no_joystick
2203 lda #128
2204 ldx #0
2205 jsr $fff4
2206 txa
2207 and #1
2208 bne check_fire_key_fire
2210 clc
2211 rts
2213 check_fire_key_no_joystick:
2215 ldx #182 ; (Return)
2216 jsr check_key
2217 cpy #255
2218 bne check_fire_key_exit
2220 check_fire_key_fire:
2222 lda $5286
2223 cmp #0
2224 bne check_fire_key_exit
2226 lda #16
2227 sta $578d
2229 jmp create_projectile ; optimise away the rts
2231 check_fire_key_exit:
2232 clc
2233 rts
2235 create_projectile:
2237 lda #2
2238 sta $5286
2240 lda $5281
2241 and #$06 ; copy the direction information
2242 asl
2243 asl
2244 asl
2245 ora $5789 ; apply the projectile type
2246 sta $5287
2248 lda $5283 ; player dy
2249 adc $577f ; add the weapon counter
2250 adc #1
2251 cmp #4 ; if dy > 3, create the projectile on the tile below
2252 bpl create_projectile_below
2254 clc
2255 sta $5289 ; dy + weapon counter + 1
2256 lda $5282 ; y
2257 sta $5288
2258 jmp create_projectile_continue
2260 create_projectile_below:
2261 sec
2262 sbc #4
2263 sta $5289 ; dy + weapon counter + 1 - 4
2264 clc
2265 lda $5282 ; y
2266 adc #1
2267 sta $5288
2269 create_projectile_continue:
2270 lda $5284 ; x
2271 sta $528a
2273 lda $5285 ; dx
2274 sta $528b
2276 lda $577f ; toggle the weapon counter
2277 eor #1
2278 sta $577f
2280 ; Move the projectile away from the player.
2282 lda #$86
2283 sta $74
2284 lda #$52
2285 sta $75
2286 jsr move_projectile_after_unplot
2288 jsr move_projectile
2290 clc
2291 rts
2293 emerge_type: ; returns A=type
2294 jsr unlimited_values
2295 lda $7d
2296 and #7
2297 cmp #4
2298 bmi emerge_type_ok
2300 sec
2301 sbc #4
2302 clc
2304 emerge_type_ok:
2305 cmp $5781 ; only allow the appropriate enemies for this level
2306 bmi emerge_type_exit
2308 sec
2309 sbc $5781
2310 clc
2312 emerge_type_exit:
2313 asl
2314 asl
2315 asl
2316 asl
2317 clc
2318 rts
2320 emerge_character: ; $74,$75=character address
2322 lda #63
2323 sta $578f
2325 jsr unlimited_values
2326 and #$0f
2327 tax
2328 lda $0ee0,x
2329 cmp #0 ; check for an invalid value and exit if found
2330 beq emerge_character_exit
2332 sta $80 ; temporary
2333 lda $0ef0,x
2334 tax
2336 ; Add an emerging enemy.
2338 ldy #0
2339 lda #3 ; emerge/explosion
2340 sta ($74),y
2342 jsr emerge_type ; obtain an enemy type
2343 iny
2344 sta ($74),y
2346 txa
2347 iny
2348 sta ($74),y ; store the y position
2349 lda #1
2350 iny
2351 sta ($74),y ; store the dy offset
2353 lda $80
2354 iny
2355 sta ($74),y ; store the x position
2356 lda #0
2357 iny
2358 sta ($74),y ; store the dx offset
2360 jsr plot_character
2362 ldx #5
2363 jsr play_sound
2365 emerge_character_exit:
2366 clc
2367 rts
2369 emerge_explode: ; $74,$75=character address
2371 jsr unplot_character
2373 ldy #1
2374 lda ($74),y ; direction/animation
2375 tax
2376 adc #1 ; update the counter
2377 and #3 ; mask off everything else
2378 sta $80 ; store the masked counter value
2379 bne move_characters_explosion_not_finished
2381 txa
2382 and #4
2383 bne move_characters_remove_character
2385 ; For emerges, convert into an enemy.
2386 txa
2387 and #$70 ; only keep bits 4,5,6
2388 ora #8 ; make this an enemy
2390 ldy #0
2391 sta ($74),y ; update the type (>= 8)
2392 iny
2393 lda $7d ; prepare the direction and animation offset
2394 and #$0c
2395 sta ($74),y
2397 jsr plot_character
2398 jmp emerge_explode_exit
2400 move_characters_remove_character:
2402 ; For finished explosions, just write 0 into the character array.
2403 lda #0
2404 ldy #0
2405 sta ($74),y
2406 jmp emerge_explode_exit
2408 move_characters_explosion_not_finished:
2409 txa
2410 and #$fc
2411 ora $80
2413 ldy #1
2414 sta ($74),y
2416 jsr plot_character
2418 emerge_explode_exit:
2419 clc
2420 rts
2422 animate_enemy_left: ; $74,$75=character address
2424 ; Set the direction and toggle the animation bit.
2426 ldy #1
2427 lda ($74),y
2428 and #$fb ; keep vertical direction bit and animation bits
2429 sta ($74),y ; left (horizontal directional bit is 0)
2431 rts
2433 move_enemy_left: ; $74,$75=character address
2435 ldy #5
2436 lda ($74),y ; read dx
2437 cmp #0
2438 beq move_enemy_left_check_x
2440 sec
2441 sbc #1
2442 ldy #5
2443 sta ($74),y ; dx
2444 clc
2445 jmp animate_enemy_left ; optimise away the rts
2447 move_enemy_left_check_x:
2449 ; Check the x offset.
2451 ldy #4
2452 lda ($74),y ; x
2453 cmp #0
2454 beq move_enemy_left_exit
2456 sec
2457 sbc #1 ; x - 1
2458 sta $81 ; temporary
2459 ldy #2
2460 lda ($74),y ; load the y offset
2461 tax ; as an index
2462 lda room_row_offsets_low,x ; read the address of the row
2463 sta $70
2464 lda #$57
2465 sta $71
2466 ldy $81 ; temporary (x - 1)
2467 lda ($70),y ; load the tile to the left
2469 cmp #0
2470 bne move_enemy_left_exit
2472 ldy #3
2473 lda ($74),y ; dy
2474 cmp #2
2475 bmi move_enemy_allow_left
2477 clc
2478 lda $70 ; dy > 1 so we need to check another tile
2479 adc #10
2480 sta $70
2481 ldy $81 ; temporary (x - 1)
2482 lda ($70),y ; load the tile below and to the left
2484 cmp #0
2485 bne move_enemy_left_exit
2487 move_enemy_allow_left:
2488 lda $81
2489 ldy #4
2490 sta ($74),y ; store the new room x offset
2491 lda #3
2492 ldy #5
2493 sta ($74),y ; dx = 3
2494 clc
2495 jmp animate_enemy_left ; optimise away the rts
2497 move_enemy_left_exit:
2498 sec
2499 rts
2501 animate_enemy_right: ; $74,$75=character address
2503 ; Set the direction and toggle the animation bit.
2505 ldy #1
2506 lda ($74),y
2507 ora #$04 ; right (keep vertical direction bit and animation bits)
2508 sta ($74),y
2510 rts
2512 move_enemy_right: ; $74,$75=character_address
2514 ldy #5
2515 lda ($74),y ; read dx
2516 cmp #0
2517 beq move_enemy_right_check_x
2518 cmp #3
2519 beq move_enemy_right_tile
2521 clc
2522 adc #1
2523 ldy #5
2524 sta ($74),y
2525 jmp animate_enemy_right ; optimise away the rts
2527 move_enemy_right_check_x: ; Check the x offset.
2529 ldy #4
2530 lda ($74),y ; x
2531 cmp #9
2532 beq move_enemy_right_exit
2534 clc
2535 adc #1 ; x + 1
2536 sta $81 ; temporary (x + 1)
2537 ldy #2
2538 lda ($74),y ; load the y offset
2539 tax ; as an index
2540 lda room_row_offsets_low,x ; read the address of the row
2541 sta $70
2542 lda #$57
2543 sta $71
2544 ldy $81 ; temporary (x + 1)
2545 lda ($70),y ; load the tile to the right
2547 cmp #0
2548 bne move_enemy_right_exit
2550 ldy #3
2551 lda ($74),y ; dy
2552 cmp #2
2553 bmi move_enemy_allow_right
2555 clc ; dy > 1 so we need to check another tile
2556 lda $70
2557 adc #10
2558 sta $70
2559 ldy $81 ; temporary (x + 1)
2560 lda ($70),y ; load the tile below and to the right
2562 cmp #0
2563 bne move_enemy_right_exit
2565 move_enemy_allow_right:
2566 clc
2568 ldy #5
2569 lda ($74),y ; dx
2570 adc #1
2571 sta ($74),y ; update dx
2572 clc
2573 jmp animate_enemy_right ; optimise away the rts
2575 move_enemy_right_tile:
2576 clc
2578 ldy #4
2579 lda ($74),y ; x
2580 adc #1
2581 sta ($74),y ; store the new room x offset
2582 lda #0
2583 iny
2584 sta ($74),y ; dx = 0
2585 clc
2586 jmp animate_enemy_right ; optimise away the rts
2588 move_enemy_right_exit:
2589 sec
2590 rts
2592 animate_enemy_up: ; $74,$75=character address
2594 ; Set the direction and toggle the animation bit.
2596 ldy #1
2597 lda ($74),y
2598 and #$f7 ; keep horizontal direction bit and animation bits
2599 sta ($74),y
2601 rts
2603 move_enemy_up: ; $74,$75=character address
2605 ldy #3
2606 lda ($74),y ; read dy
2607 cmp #0
2608 beq move_enemy_up_check_y
2610 sec
2611 sbc #1
2612 ldy #3
2613 sta ($74),y ; dy
2614 clc
2615 jmp animate_enemy_up ; optimise away the rts
2617 move_enemy_up_check_y:
2619 ; Check the y offset.
2621 ldy #2
2622 lda ($74),y ; y
2623 cmp #0
2624 beq move_enemy_up_exit
2626 tax ; use the y offset as an index
2627 dex ; y - 1
2628 ldy #4
2629 lda ($74),y ; load the x offset
2630 sta $81 ; temporary (x)
2631 tay
2632 lda room_row_offsets_low,x ; read the address of the row
2633 sta $70
2634 lda #$57
2635 sta $71
2636 lda ($70),y ; load the tile above
2638 cmp #0
2639 bne move_enemy_up_exit
2641 ldy #5
2642 lda ($74),y ; dx
2643 cmp #0
2644 beq move_enemy_allow_up
2646 clc ; dx != 0 so we need to check another tile
2647 ldy $81
2648 iny
2649 lda ($70),y ; load the tile above and to the right
2651 cmp #0
2652 bne move_enemy_up_exit
2654 move_enemy_allow_up:
2655 txa
2656 ldy #2
2657 sta ($74),y ; store the new room y offset
2658 lda #3
2659 iny
2660 sta ($74),y ; dy = 3
2661 clc
2662 jmp animate_enemy_up ; optimise away the rts
2664 move_enemy_up_exit:
2665 sec
2666 rts
2668 animate_enemy_down: ; $74,$75=character address
2670 ; Set the direction and toggle the animation bit.
2672 ldy #1
2673 lda ($74),y
2674 ora #$08 ; down
2675 sta ($74),y
2677 rts
2679 move_enemy_down: ; $74,$75=character address
2681 ldy #3
2682 lda ($74),y ; dy
2683 cmp #1
2684 beq move_enemy_down_check_y
2685 cmp #3
2686 beq move_enemy_down_tile
2688 adc #1
2689 ldy #3
2690 sta ($74),y ; dy
2691 clc
2692 jmp animate_enemy_down ; optimise away the rts
2694 move_enemy_down_check_y:
2696 ; Check the y offset.
2698 ldy #2
2699 lda ($74),y
2700 cmp #9
2701 beq move_enemy_down_exit
2703 clc
2704 adc #1 ; y + 1
2705 tax
2706 ldy #4
2707 lda ($74),y ; load the x offset
2708 sta $81 ; temporary
2709 tay
2710 lda room_row_offsets_low,x ; read the address of the row
2711 sta $70
2712 lda #$57
2713 sta $71
2714 lda ($70),y ; load the tile below
2716 cmp #0
2717 bne move_enemy_down_exit
2719 ldy #5
2720 lda ($74),y ; dx
2721 cmp #0
2722 beq move_enemy_allow_down
2724 clc ; dx != 0 so we need to check another tile
2725 ldy $81 ; x
2726 iny
2727 lda ($70),y ; load the tile below and to the right
2729 cmp #0
2730 bne move_enemy_down_exit
2732 move_enemy_allow_down:
2733 clc
2735 ldy #3
2736 lda ($74),y ; dy
2737 adc #1
2738 sta ($74),y ; update dy
2739 clc
2740 jmp animate_enemy_down ; optimise away the rts
2742 move_enemy_down_tile:
2743 clc
2745 ldy #2
2746 lda ($74),y ; y
2747 adc #1
2748 sta ($74),y ; store the new room y offset
2749 lda #0
2750 iny
2751 sta ($74),y ; dy = 0
2752 clc
2753 jmp animate_enemy_down ; optimise away the rts
2755 move_enemy_down_exit:
2756 sec
2757 rts
2759 move_enemy_animate: ; $74,$75=character address
2761 ldy #1
2762 lda ($74),y ; direction/animation
2763 sta $81
2764 and #$03
2765 adc #1
2766 and #$03 ; keep animation bits
2767 sta $8f
2768 lda $81
2769 and #$fc ; mask off the animation bits
2770 ora $8f
2771 sta ($74),y
2772 rts
2774 move_enemy_next_direction: .byte $04, $0c, $00, $08
2776 move_enemy: ; $74,$75=character address
2778 lda #0
2779 sta $8d ; vertical motion value (0=no motion; 1=up; 2=down)
2780 lda #0
2781 sta $8e ; horizontal motion value (0=no motion; 1=left; 2=right)
2783 lda ($74),y ; read the enemy number (Y should be zero)
2784 and #$10
2785 beq move_enemy_homing
2786 clc
2788 ; This enemy is a non-homing enemy.
2790 jsr unplot_character ; unplot now before we change the sprite used
2792 ldy #1
2793 lda ($74),y
2794 and #$f0
2795 cmp #$f0
2796 bne move_enemy_set_direction
2797 clc
2799 ldy #1
2800 lda ($74),y
2801 and #$0c
2802 ror
2803 ror
2804 tax
2805 lda move_enemy_next_direction,x
2806 sta ($74),y
2808 move_enemy_set_direction:
2809 clc
2811 ldy #1
2812 lda ($74),y
2813 sta $7b
2815 adc #$10
2816 sta ($74),y
2817 clc
2819 lda $7b
2820 and #$04
2821 ror
2822 ror
2823 adc #1
2824 sta $8e
2826 lda $7b
2827 and #$08
2828 ror
2829 ror
2830 ror
2831 adc #1
2832 sta $8d
2834 jmp move_enemy_with_direction
2836 move_enemy_homing:
2838 ldy #2
2839 lda ($74),y ; y
2840 cmp $5282 ; player y
2841 bmi move_enemy_downwards
2842 bne move_enemy_upwards
2844 ldy #3
2845 lda ($74),y ; dy
2846 cmp $5283 ; player y
2847 beq move_enemy_horizontally
2848 bpl move_enemy_upwards
2850 move_enemy_downwards:
2851 lda #2
2852 sta $8d
2853 jmp move_enemy_horizontally
2855 move_enemy_upwards:
2856 lda #1
2857 sta $8d
2858 ;jmp move_enemy_horizontally
2860 move_enemy_horizontally:
2861 ldy #4
2862 lda ($74),y ; x
2863 cmp $5284 ; player x
2864 bmi move_enemy_rightwards
2865 bne move_enemy_leftwards
2867 ldy #5
2868 lda ($74),y ; dx
2869 cmp #0
2870 beq move_enemy_with_direction_unplot
2871 bpl move_enemy_leftwards
2873 move_enemy_rightwards:
2874 lda #2
2875 sta $8e
2876 jmp move_enemy_with_direction_unplot
2878 move_enemy_leftwards:
2879 lda #1
2880 sta $8e
2882 move_enemy_with_direction_unplot:
2883 clc
2885 jsr unplot_character
2887 move_enemy_with_direction:
2888 clc
2890 lda $8e
2891 cmp #1
2892 bne move_enemy_not_left
2893 jsr move_enemy_left
2894 clc
2895 jmp move_enemy_not_right
2897 move_enemy_not_left:
2898 lda $8e
2899 cmp #2
2900 bne move_enemy_not_right
2901 jsr move_enemy_right
2902 clc
2904 move_enemy_not_right:
2905 lda $8d
2906 cmp #1
2907 bne move_enemy_not_up
2908 jsr move_enemy_up
2909 clc
2910 jmp move_enemy_toggle
2912 move_enemy_not_up:
2913 lda $8d
2914 cmp #2
2915 bne move_enemy_toggle
2916 jsr move_enemy_down
2918 move_enemy_toggle:
2919 clc
2920 jsr move_enemy_animate
2921 jmp plot_character ; optimise away the rts
2923 move_enemy_exit:
2924 clc
2925 rts
2927 create_explosion: ; X=y, Y=x
2929 lda #3
2930 sta $52a4
2931 lda #4
2932 sta $52a5
2933 txa
2934 sta $52a6
2935 lda #1
2936 sta $52a7
2937 tya
2938 sta $52a8
2939 lda #0
2940 sta $52a9
2941 rts
2943 move_projectile_left:
2945 lda $528b
2946 cmp #0
2947 beq move_projectile_left_check_x
2949 dec $528b
2950 clc
2951 rts
2953 move_projectile_left_check_x:
2955 lda $528a
2956 cmp #0
2957 bne move_projectile_left_in_room
2958 jmp move_projectile_left_exit
2960 move_projectile_left_in_room:
2961 tay
2962 dey ; x - 1
2963 ldx $5288 ; y
2964 lda room_row_offsets_low,x ; read the address of the row
2965 sta $70
2966 lda #$57
2967 sta $71
2968 lda ($70),y ; load the tile to the left
2970 cmp #0
2971 bne move_projectile_left_wall
2973 lda $5289 ; dy
2974 cmp #3
2975 bmi move_projectile_allow_left
2977 clc ; dy > 2 so we need to check another tile
2978 lda $70
2979 adc #10
2980 sta $70
2981 lda ($70),y ; load the tile below and to the left
2982 inx ; y += 1
2984 cmp #0
2985 bne move_projectile_left_wall
2987 move_projectile_allow_left:
2989 sty $528a ; x
2990 lda #3
2991 sta $528b ; dx = 3
2993 clc
2994 rts
2996 move_projectile_left_wall: ; the projectile hit a wall
2997 clc
2999 lda $5287 ; type 2 can pass through walls
3000 and #$06
3001 cmp #4
3002 beq move_projectile_allow_left
3004 cmp #2
3005 bne move_projectile_left_not_boomerang
3007 lda $5287
3008 and #$0f
3009 cmp #8
3010 bpl move_projectile_left_exit
3012 ldx $577f ; weapon counter
3013 ora boomerang_horizontal,x
3014 sta $5287
3015 clc
3016 rts ; exit without moving or registering a collision
3018 move_projectile_left_not_boomerang:
3020 cmp #6 ; type 3 can destroy certain walls
3021 bne move_projectile_left_exit
3023 lda ($70),y ; load the tile to the left
3024 cmp #1 ; decoration can be destroyed
3025 bne move_projectile_left_exit
3026 clc
3028 lda #0
3029 sta ($70),y
3031 ; X=y, Y=x
3032 jsr create_explosion
3033 jsr plot_blank_xy ; corrupted X
3035 lda #$a4
3036 sta $74
3037 lda #$52
3038 sta $75
3039 jsr plot_character
3041 ldx #0
3042 jsr play_sound
3044 lda #16 ; prevent the player from firing a new
3045 sta $578d ; projectile until the explosion has finished
3047 move_projectile_left_exit:
3048 sec
3049 rts
3051 boomerang_horizontal: .byte $28, $38
3053 move_projectile_right:
3055 ; Fire right.
3057 lda $528b
3058 cmp #2
3059 beq move_projectile_right_check_x
3060 cmp #3
3061 beq move_projectile_right_tile
3063 inc $528b
3064 clc
3065 rts
3067 move_projectile_right_check_x:
3069 lda $528a ; x
3070 cmp #9
3071 bne move_projectile_right_not_edge
3072 jmp move_projectile_right_exit
3074 move_projectile_right_not_edge:
3075 clc
3076 tay
3077 iny ; x + 1
3078 ldx $5288 ; y
3079 lda room_row_offsets_low,x ; read the address of the row
3080 sta $70
3081 lda #$57
3082 sta $71
3083 lda ($70),y ; load the tile to the right
3085 cmp #0
3086 bne move_projectile_right_wall
3088 lda $5289 ; dy
3089 cmp #3
3090 bmi move_projectile_allow_right
3092 clc ; dy > 2 so we need to check another tile
3093 lda $70
3094 adc #10
3095 sta $70
3096 lda ($70),y ; load the tile below and to the right
3097 inx ; y += 1
3099 cmp #0
3100 bne move_projectile_right_wall
3102 move_projectile_allow_right:
3104 inc $528b ; dx
3105 clc
3106 rts
3108 move_projectile_right_tile:
3110 inc $528a ; x
3111 lda #0
3112 sta $528b ; dx
3113 clc
3114 rts
3116 move_projectile_right_wall: ; the projectile hit a wall
3117 clc
3119 lda $5287 ; type 2 can pass through walls
3120 and #$06
3121 cmp #4
3122 beq move_projectile_allow_right
3124 cmp #2
3125 bne move_projectile_right_not_boomerang
3127 lda $5287
3128 and #$0f
3129 cmp #8
3130 bpl move_projectile_right_exit
3132 ldx $577f ; weapon counter
3133 ora boomerang_horizontal,x
3134 sta $5287
3135 clc
3136 rts ; exit without moving or registering a collision
3138 move_projectile_right_not_boomerang:
3140 cmp #6 ; type 3 can destroy certain walls
3141 bne move_projectile_right_exit
3143 lda ($70),y ; load the tile to the right
3144 cmp #1 ; decoration can be destroyed
3145 bne move_projectile_right_exit
3146 clc
3148 lda #0
3149 sta ($70),y
3151 ; X=y, Y=x
3152 jsr create_explosion
3153 jsr plot_blank_xy ; corrupted X
3155 lda #$a4
3156 sta $74
3157 lda #$52
3158 sta $75
3159 jsr plot_character
3161 ldx #0
3162 jsr play_sound
3164 lda #16 ; prevent the player from firing a new
3165 sta $578d ; projectile until the explosion has finished
3167 move_projectile_right_exit:
3168 sec
3169 rts
3171 move_projectile_up:
3173 lda $5289 ; read dy
3174 cmp #0
3175 beq move_projectile_up_check_y
3177 dec $5289
3178 clc
3179 rts
3181 move_projectile_up_check_y: ; Check the y offset.
3183 lda $5288
3184 cmp #0
3185 bne move_projectile_up_not_edge
3186 jmp move_projectile_up_exit
3188 move_projectile_up_not_edge:
3189 tax ; use the y offset as an index
3190 dex ; y - 1
3191 ldy $528a ; load the x offset
3192 lda room_row_offsets_low,x ; read the address of the row
3193 sta $70
3194 lda #$57
3195 sta $71
3196 lda ($70),y ; load the tile above
3198 cmp #0
3199 bne move_projectile_up_wall
3201 lda $528b ; dx
3202 cmp #3
3203 bmi move_projectile_allow_up
3205 clc ; dx > 2 so we need to check another tile
3206 iny
3207 lda ($70),y ; load the tile above and to the right
3209 cmp #0
3210 bne move_projectile_up_wall
3212 move_projectile_allow_up:
3213 txa
3214 sta $5288 ; store the new room y offset
3215 lda #3
3216 sta $5289 ; dy = 3
3218 clc
3219 rts
3221 move_projectile_up_wall: ; the projectile hit a wall
3222 clc
3224 lda $5287 ; type 2 can pass through walls
3225 and #$06
3226 cmp #4
3227 beq move_projectile_allow_up
3229 cmp #2
3230 bne move_projectile_up_not_boomerang
3232 lda $5287
3233 and #$0f
3234 cmp #8
3235 bpl move_projectile_up_exit
3237 ldx $577f ; weapon counter
3238 ora boomerang_vertical,x
3239 sta $5287
3240 clc
3241 rts ; exit without moving or registering a collision
3243 move_projectile_up_not_boomerang:
3245 cmp #6 ; type 3 can destroy certain walls
3246 bne move_projectile_up_exit
3248 lda ($70),y ; load the tile above
3249 cmp #1 ; decoration can be destroyed
3250 bne move_projectile_up_exit
3251 clc
3253 lda #0
3254 sta ($70),y
3256 ; X=y, Y=x
3257 jsr create_explosion
3258 jsr plot_blank_xy ; corrupted X
3260 lda #$a4
3261 sta $74
3262 lda #$52
3263 sta $75
3264 jsr plot_character
3266 ldx #0
3267 jsr play_sound
3269 lda #16 ; prevent the player from firing a new
3270 sta $578d ; projectile until the explosion has finished
3272 move_projectile_up_exit:
3273 sec
3274 rts
3276 boomerang_vertical: .byte $08, $18
3278 move_projectile_down:
3280 lda $5289 ; read dy
3281 cmp #2
3282 beq move_projectile_down_check_y
3283 cmp #3
3284 beq move_projectile_down_tile
3286 inc $5289 ; 0 <= dy < 3
3287 clc
3288 rts
3290 move_projectile_down_check_y: ; Check the y offset.
3292 lda $5288
3293 cmp #9
3294 bne move_projectile_down_in_room
3295 jmp move_projectile_down_exit
3297 move_projectile_down_in_room:
3298 clc
3299 tax
3300 inx ; y + 1
3301 ldy $528a ; load the x offset
3302 lda room_row_offsets_low,x ; read the address of the row
3303 sta $70
3304 lda #$57
3305 sta $71
3306 lda ($70),y ; load the tile below
3308 cmp #0
3309 bne move_projectile_down_wall
3311 lda $528b ; dx
3312 cmp #3
3313 bmi move_projectile_allow_down
3315 clc ; dx > 2 so we need to check another tile
3316 iny
3317 lda ($70),y ; load the tile below and to the right
3319 cmp #0
3320 bne move_projectile_down_wall
3322 move_projectile_allow_down:
3324 inc $5289 ; update dy
3325 clc
3326 rts
3328 move_projectile_down_tile:
3330 inc $5288 ; store the new room y offset
3331 lda #0
3332 sta $5289 ; dy = 0
3333 clc
3334 rts
3336 move_projectile_down_wall: ; the projectile hit a wall
3337 clc
3339 lda $5287 ; type 2 can pass through walls
3340 and #$06
3341 cmp #4
3342 beq move_projectile_allow_down
3344 cmp #2
3345 bne move_projectile_down_not_boomerang
3347 lda $5287
3348 and #$0f
3349 cmp #8
3350 bpl move_projectile_down_exit
3352 ldx $577f ; weapon counter
3353 ora boomerang_vertical,x
3354 sta $5287
3355 clc
3356 rts ; exit without moving or registering a collision
3358 move_projectile_down_not_boomerang:
3360 cmp #6 ; type 3 can destroy certain walls
3361 bne move_projectile_down_exit
3363 lda ($70),y ; load the tile below
3364 cmp #1 ; decoration can be destroyed
3365 bne move_projectile_down_exit
3366 clc
3368 lda #0
3369 sta ($70),y
3371 ; X=y, Y=x
3372 jsr create_explosion
3373 jsr plot_blank_xy ; corrupted X
3375 lda #$a4
3376 sta $74
3377 lda #$52
3378 sta $75
3379 jsr plot_character
3381 ldx #0
3382 jsr play_sound
3384 lda #16 ; prevent the player from firing a new
3385 sta $578d ; projectile until the explosion has finished
3387 move_projectile_down_exit:
3388 sec
3389 rts
3391 move_projectile_animate:
3393 lda $5287
3394 eor #1
3395 sta $5287
3396 rts
3398 move_projectile:
3400 lda $5286
3401 cmp #0
3402 bne move_projectile_move
3403 jmp move_projectile_exit
3405 move_projectile_move:
3406 clc
3408 lda #$86
3409 sta $74
3410 lda #$52
3411 sta $75
3412 jsr unplot_character
3414 move_projectile_after_unplot:
3416 lda $5287
3417 and #$30 ; direction
3419 cmp #0
3420 bne move_projectile_not_left
3422 jsr move_projectile_left
3423 bcc move_projectile_toggle
3424 bcs move_projectile_destroy
3426 move_projectile_not_left:
3427 cmp #$10
3428 bne move_projectile_not_right
3430 jsr move_projectile_right
3431 bcc move_projectile_toggle
3432 bcs move_projectile_destroy
3434 move_projectile_not_right:
3435 cmp #$20
3436 bne move_projectile_not_up
3438 jsr move_projectile_up
3439 bcc move_projectile_toggle
3440 bcs move_projectile_destroy
3442 move_projectile_not_up:
3443 cmp #$30
3444 bne move_projectile_toggle
3446 jsr move_projectile_down
3447 bcs move_projectile_destroy
3449 move_projectile_toggle:
3451 jsr projectile_collide
3452 bcs move_projectile_destroy
3454 jsr move_projectile_animate
3456 lda #$86
3457 sta $74
3458 lda #$52
3459 sta $75
3460 jmp plot_character ; optimise away the rts
3462 move_projectile_destroy:
3463 clc
3465 ldy #0
3466 lda ($74),y ; type
3467 cmp #8
3468 bmi move_projectile_no_enemy_collision
3470 and #$70 ; increase the player's score
3471 lsr
3472 lsr
3473 lsr
3474 adc #2
3475 sta $70
3476 jsr add_score
3477 jmp move_projectile_create_explosion
3479 move_projectile_no_enemy_collision:
3481 cmp #4 ; items can be destroyed as well
3482 bne move_projectile_no_item_collision
3484 ldy #1 ; but not keys
3485 lda ($74),y
3486 cmp #4 ; even the mace is stopped by a key
3487 beq move_projectile_remove_projectile
3488 clc
3490 jsr remove_room_item
3492 move_projectile_create_explosion:
3494 ; Unplot the item/enemy and replace it with an explosion.
3496 jsr unplot_character
3498 lda #3 ; explosion
3499 ldy #0
3500 sta ($74),y
3502 lda #4
3503 ldy #1
3504 sta ($74),y
3506 jsr plot_character
3508 ; Play a sound.
3509 ldx #0
3510 jsr play_sound
3512 move_projectile_no_item_collision:
3514 lda $5287 ; type 2 projectiles pass through everything
3515 and #$06
3516 cmp #4
3517 bne move_projectile_remove_projectile
3519 ; Ideally, we would have recorded if the projectile left the screen so
3520 ; that we don't perform these checks again here, but it would just add
3521 ; overhead to the normal movement routines for the other weapons.
3523 lda $5288 ; y
3524 cmp #0
3525 beq move_projectile_remove_projectile
3526 cmp #9
3527 beq move_projectile_remove_projectile
3529 lda $528a ; x
3530 cmp #0
3531 beq move_projectile_remove_projectile
3532 cmp #9
3533 beq move_projectile_remove_projectile
3535 clc
3536 lda #$86
3537 sta $74
3538 lda #$52
3539 sta $75
3541 jsr plot_character
3542 jmp move_projectile_exit
3544 move_projectile_remove_projectile:
3546 lda #0 ; remove the projectile from the character list
3547 sta $5286
3549 move_projectile_exit:
3550 clc
3551 rts
3553 emerge_characters:
3555 lda #$8c ; set the character address
3556 sta $74
3557 lda #$52
3558 sta $75
3560 emerge_characters_loop:
3562 ldy #0
3563 lda ($74),y
3564 cmp #0
3565 bne emerge_characters_next
3567 jmp emerge_character ; optimise away the rts
3569 emerge_characters_next:
3570 clc
3572 ; Examine the next character.
3573 lda $74
3574 adc #6
3576 cmp #$a4
3577 bpl emerge_characters_exit
3578 sta $74
3579 jmp emerge_characters_loop
3581 emerge_characters_exit:
3582 clc
3583 rts
3585 enemy_slots: .byte 0, 6, 12, 18
3587 move_characters:
3589 lda #$8c ; set the character address
3590 sta $74
3591 lda #$52
3592 sta $75
3594 lda $578e ; read a value from 0 to 3 from the motion counter
3595 and #3
3596 tax
3597 lda enemy_slots,x ; look up the corresponding slot in the character list
3598 adc $74
3599 sta $74 ; update the character address
3601 move_characters_loop:
3603 ldy #0
3604 lda ($74),y
3605 cmp #3
3606 bne move_characters_not_emerge_explode
3608 jsr emerge_explode
3609 jmp move_characters_next
3611 move_characters_not_emerge_explode:
3612 cmp #8
3613 bmi move_characters_next
3615 jsr move_enemy
3617 move_characters_next:
3618 clc
3620 lda $74 ; for the last enemy, check the next slot
3621 cmp #$9e ; for the presence of an explosion
3622 bne move_characters_endloop ; otherwise leave the loop (only performing
3623 clc ; one iteration)
3625 adc #6
3626 sta $74
3627 jmp move_characters_loop
3629 move_characters_endloop:
3630 clc
3632 ; Check collisions with the player.
3634 jsr player_collide
3635 bcs move_characters_collisions
3636 jmp move_characters_exit
3638 move_characters_collisions:
3639 clc
3641 ldy #0
3642 lda ($74),y ; type
3643 cmp #8
3644 bpl move_character_destroy_enemy
3646 ; Unplot the item.
3647 jsr unplot_character
3649 ; Remove it from the item table.
3650 jsr remove_room_item
3652 lda #0 ; remove the item from the character list
3653 ldy #0
3654 sta ($74),y
3656 iny
3657 lda ($74),y ; get the item type
3659 sta $8d ; temporarily store A and increase the score
3660 tax
3661 lda item_scores,x
3662 sta $70
3663 jsr add_score
3664 lda $8d
3666 ; Check the item type.
3667 cmp #8
3668 bmi move_characters_not_health
3670 lda #20
3671 sta $70
3672 jsr add_strength
3673 clc
3675 ldx #2
3676 jsr play_sound
3678 rts
3680 move_characters_not_health:
3681 cmp #5
3682 bmi move_characters_not_treasure
3684 ldx #2
3685 jsr play_sound
3687 clc
3688 rts
3690 move_characters_not_treasure:
3691 cmp #4
3692 bmi move_characters_not_key
3694 ; Key - update the item/player flags byte.
3695 lda $5780
3696 ora #$01
3697 sta $5780
3698 clc
3700 ldx #3
3701 jsr play_sound
3703 rts
3705 move_characters_not_key:
3707 ; Update the player's weapon.
3708 asl
3709 sta $5789
3710 clc
3712 ldx #2
3713 jsr play_sound
3715 rts
3717 move_character_destroy_enemy:
3719 ; Unplot the enemy and replace it with an explosion.
3721 jsr unplot_character
3723 lda #3 ; explosion
3724 ldy #0
3725 sta ($74),y
3727 lda #4
3728 ldy #1
3729 sta ($74),y
3731 jsr plot_character
3733 ; Reduce the player's strength.
3735 ldx #1
3736 jsr play_sound
3738 lda #1
3739 sta $70
3740 jmp reduce_strength ; optimise away the rts
3742 move_characters_exit:
3743 clc
3744 rts
3746 remove_room_item:
3748 ldx $5782 ; current room row number
3749 lda eleven_times_table,x
3750 adc $5783 ; current room column number
3751 tax
3752 lda #$80 ; store a value with the top bit set instead of zero because we
3753 sta $5200,x ; have visited this room if we can collect the object within it
3754 clc
3755 rts
3757 item_scores: .byte $1,$4,$9,$16, $50,$20,$5,$10,$40
3758 score_vdu_bytes: .byte 1,1,31 ; reversed
3759 score_digits: .byte "0123456789"
3761 add_score: ; $70=score to add
3763 sed
3764 lda $5786
3765 adc $70
3766 sta $5786
3767 lda $5787
3768 adc #0
3769 sta $5787
3770 lda $5788
3771 adc #0
3772 sta $5788
3773 cld
3775 write_score:
3777 lda #$86
3778 sta $70
3779 lda #$57
3780 sta $71
3782 ldx #2
3783 write_score_vdu_bytes:
3784 lda score_vdu_bytes,x
3785 jsr $ffee
3786 dex
3787 bpl write_score_vdu_bytes
3789 write_score_digits: ; $70,$71=address of score bytes
3791 ldy #2
3792 write_score_loop:
3794 lda ($70),y
3795 lsr
3796 lsr
3797 lsr
3798 lsr
3799 tax
3800 lda score_digits,x
3801 jsr $ffee
3803 lda ($70),y
3804 and #$0f
3805 tax
3806 lda score_digits,x
3807 jsr $ffee
3809 dey
3810 bpl write_score_loop
3812 clc
3813 rts
3815 strength_units: .byte $00,$88,$cc,$ee
3817 add_strength: ; $70=strength to add
3819 ; Divide the initial strength by 4 to determine which half character to
3820 ; start plotting at, and multiply by 8 to get the address. The net result
3821 ; is to mask off the bottom two bits and shift left once.
3822 lda $5784
3823 and #$fc
3824 sta $71 ; strength rounded down to a multiple of four units
3825 asl
3826 clc
3827 tay
3829 lda $5784
3830 adc $70
3831 cmp #65
3832 bmi add_strength_update
3834 lda #64
3836 add_strength_update:
3837 clc
3838 sta $5784 ; the final strength
3840 sec
3841 sbc $71
3842 clc
3843 tax ; the number of units to add between the rounded original
3844 ; strength and the final strength
3846 lda #$f3 ; the start of the strength bar
3847 sta $72
3848 lda #$59
3849 sta $73
3851 cpx #4
3852 bmi add_strength_loop_extra
3854 add_strength_loop:
3856 clc
3857 lda #$ff
3858 sta ($72),y
3860 tya
3861 adc #8
3862 tay
3864 txa
3865 sec
3866 sbc #4
3867 clc
3868 tax
3870 cmp #4
3871 bpl add_strength_loop
3873 add_strength_loop_extra:
3874 cpx #0
3875 beq add_strength_exit
3877 ; For any remaining units in excess of the multiples of four units, plot
3878 ; the appropriate byte.
3879 lda $5784
3880 and #3
3881 tax
3883 lda strength_units,x
3884 sta ($72),y
3886 add_strength_exit:
3887 clc
3888 rts
3890 reduce_strength: ; $70=strength to remove
3892 lda $5784
3893 tax
3894 sec
3895 sbc $70
3896 bpl reduce_strength_update
3898 lda #0
3900 reduce_strength_update:
3901 clc
3902 sta $5784
3904 ; Divide the final strength by 4 to determine which half character to
3905 ; plot, and multiply by 8 to get the address. The net result is to mask off
3906 ; the bottom two bits and shift left once.
3907 and #$fc
3908 asl
3909 tay
3911 lda #$f3 ; the start of the strength bar
3912 sta $70
3913 lda #$59
3914 sta $71
3916 lda $5784
3917 and #3
3918 tax
3919 lda strength_units,x
3920 sta ($70),y
3922 lda $5784
3923 cmp #0
3924 bne reduce_strength_exit
3926 lda $5780 ; the player ran out of strength
3927 ora #$40
3928 sta $5780
3930 lda #64 ; reset the delay counter
3931 sta $5785
3933 lda #$80 ; unplot the player
3934 sta $74
3935 lda #$52
3936 sta $75
3938 jsr unplot_character
3940 lda #8 ; change the player's direction to the demise animation
3941 sta $5281
3943 jsr plot_character
3944 jmp destroy_enemies ; optimise away the rts
3946 reduce_strength_exit:
3947 clc
3948 rts
3950 destroy_enemies:
3952 lda #$8c
3953 sta $74
3954 lda #$52
3955 sta $75
3957 destroy_enemies_loop:
3959 ldy #0
3960 lda ($74),y
3961 cmp #8
3962 bmi destroy_enemies_not_enemy
3964 jsr unplot_character
3966 lda #3 ; emerge/explosion
3967 ldy #0
3968 sta ($74),y
3970 iny
3971 lda #4 ; explosion
3972 sta ($74),y
3974 jsr plot_character
3975 jmp destroy_enemies_not_emerging_enemy
3977 destroy_enemies_not_enemy:
3978 cmp #3
3979 bne destroy_enemies_not_emerging_enemy
3981 jsr unplot_character
3983 iny ; whether emerging or exploding, ensure that the enemy
3984 lda ($74),y ; is now exploding
3985 ora #4
3986 sta ($74),y
3988 jsr plot_character
3990 destroy_enemies_not_emerging_enemy:
3991 clc
3992 lda $74
3993 adc #6
3994 sta $74
3995 cmp #$a4
3996 bmi destroy_enemies_loop
3998 clc
3999 rts
4001 remove_characters:
4003 ; Clear the character table.
4005 ldx #6
4006 remove_characters_loop:
4007 lda #0
4008 sta $5280,x
4009 txa
4010 adc #6
4011 tax
4012 cpx #$2a
4013 bmi remove_characters_loop
4015 rts
4017 ; The player collision masks use bits to represent where the player is in a
4018 ; tile. See the collisions.txt file for more information.
4020 ; Player is above, enemy is below, checking the overlap in the lower tile.
4021 player_collision_mask_above: .byte $00, $c0, $f0, $fc
4023 projectile_collision_mask_above: .byte $00, $00, $00, $80
4025 ; Player and enemy share the same tile or player is on the tile below.
4026 player_collision_mask_below: .byte $ff, $3f, $0f, $03
4028 projectile_collision_mask_below: .byte $e0, $38, $e0, $03
4030 ; Player is above or on the same tile, enemy is below, checking the overlap in
4031 ; the lower tile.
4032 enemy_collision_mask_above: .byte $f8, $3f, $0f, $03
4034 ; Enemy is above, player is below, checking the overlap in the lower tile.
4035 enemy_collision_mask_below: .byte $00, $00, $c0, $f0
4037 ; Player is to the left, enemy is to the right, checking the overlap in the
4038 ; right hand tile.
4039 player_collision_mask_left:
4040 projectile_collision_mask_left: .byte $00, $00, $00, $08
4042 ; Player and enemy share the same tile or player is on the tile to the right.
4043 player_collision_mask_right:
4044 projectile_collision_mask_right: .byte $0c, $06, $03, $01
4046 ; Player is to the left, enemy is to the right or on the same tile, checking
4047 ; the overlap in the right hand tile.
4048 enemy_collision_mask_left: .byte $0f, $07, $03, $01
4050 ; Enemy is to the left, player is to the right, checking the overlap in the
4051 ; right hand tile.
4052 enemy_collision_mask_right: .byte $00, $08, $0c, $0e
4054 player_collide:
4056 lda $5282 ; player y
4057 sta $8a
4058 lda $5284 ; player x
4059 sta $8b
4061 ldx $5283 ; player dy
4062 lda player_collision_mask_above,x
4063 sta $86
4064 lda player_collision_mask_below,x
4065 sta $88
4066 ldx $5285 ; player dx
4067 lda player_collision_mask_left,x
4068 sta $87
4069 lda player_collision_mask_right,x
4070 sta $89
4072 jmp collide ; optimise away the rts
4074 projectile_collide:
4076 lda $5288 ; projectile y
4077 sta $8a
4078 lda $528a ; projectile x
4079 sta $8b
4081 ldx $5289 ; projectile dy
4082 lda projectile_collision_mask_above,x
4083 sta $86
4084 lda projectile_collision_mask_below,x
4085 sta $88
4086 ldx $528b ; projectile dx
4087 lda projectile_collision_mask_left,x
4088 sta $87
4089 lda projectile_collision_mask_right,x
4090 sta $89
4092 ; Run on into the next routine.
4094 collide:
4096 lda #$8c ; set the character address
4097 sta $74
4098 lda #$52
4099 sta $75
4101 collide_loop:
4103 ldy #0
4104 lda ($74),y ; type
4105 cmp #4
4106 bpl collide_check
4108 jmp collide_next
4110 collide_check:
4112 ldy #2
4113 lda ($74),y ; y
4114 sec
4115 sbc $8a ; y - player/projectile y
4116 beq check_collide_y_equal
4117 cmp #1
4118 beq check_collide_y_greater
4119 cmp #255
4120 beq check_collide_y_less
4122 jmp collide_next
4124 check_collide_y_equal:
4125 ; The enemy is on the same tile as the player/projectile so look at the
4126 ; collision on their common tile.
4127 ldy #3
4128 lda ($74),y ; dy
4129 tax
4130 lda enemy_collision_mask_above,x
4131 and $88 ; player/projectile mask below
4132 bne check_collide_x
4134 jmp collide_next
4136 check_collide_y_greater:
4137 ; The enemy is on the tile below the player/projectile so look at the
4138 ; collision on the enemy's tile.
4139 ldy #3
4140 lda ($74),y ; dy
4141 tax
4142 lda enemy_collision_mask_above,x
4143 and $86 ; player mask above
4144 bne check_collide_x
4146 jmp collide_next
4148 check_collide_y_less:
4149 ; The enemy is on the tile above the player/projectile so look at the
4150 ; collision on the player's tile.
4151 ldy #3
4152 lda ($74),y ; dy
4153 tax
4154 lda enemy_collision_mask_below,x
4155 and $88 ; player mask below
4156 bne check_collide_x
4158 jmp collide_next
4160 check_collide_x:
4161 ldy #4
4162 lda ($74),y ; x
4163 sec
4164 sbc $8b ; x - player/projectile x
4165 beq check_collide_x_equal
4166 cmp #1
4167 beq check_collide_x_greater
4168 cmp #255
4169 beq check_collide_x_less
4171 jmp collide_next
4173 check_collide_x_equal:
4174 ; The enemy is on the same tile as the player/projectile so look at the
4175 ; collision on their common tile.
4176 ldy #5
4177 lda ($74),y ; dx
4178 tax
4179 lda enemy_collision_mask_left,x
4180 and $89 ; player mask right
4181 bne check_collide_destroy
4183 jmp collide_next
4185 check_collide_x_greater:
4186 ; The enemy is the tile to the right of the player/projectile so look
4187 ; at the collision on the enemy's tile.
4188 ldy #5
4189 lda ($74),y ; dx
4190 tax
4191 lda enemy_collision_mask_left,x
4192 and $87 ; player mask left
4193 bne check_collide_destroy
4195 jmp collide_next
4197 check_collide_x_less:
4198 ; The enemy is the tile to the left of the player/projectile so look at
4199 ; the collision on the player's tile.
4200 ldy #5
4201 lda ($74),y ; dx
4202 tax
4203 lda enemy_collision_mask_right,x
4204 and $89 ; player mask right
4205 bne check_collide_destroy
4207 collide_next:
4208 clc
4210 ; Examine the next character.
4211 lda $74
4212 adc #6
4214 cmp #$a4
4215 bpl collide_exit
4216 sta $74
4217 jmp collide_loop
4219 check_collide_destroy:
4221 sec ; set the carry flag to inform the caller that the
4222 rts ; player/projectile should be destroyed
4224 collide_exit:
4225 clc
4226 rts
4228 blank_screen:
4229 lda #1
4230 sta $70
4231 lda #0
4232 sta $71
4233 jsr set_palette
4234 lda #2
4235 sta $70
4236 lda #0
4237 sta $71
4238 jsr set_palette
4239 lda #3
4240 sta $70
4241 lda #0
4242 sta $71
4243 ; Run on into set_palette.
4245 set_palette:
4246 ; $70=logical colour
4247 ; $71=physical colour
4248 lda $70
4249 sta $578b
4250 lda $71
4251 sta $578c
4252 lda #0
4253 sta $578d
4254 sta $578e
4255 sta $578f
4257 lda #$c
4258 ldx #$8b
4259 ldy #$57
4260 jsr $fff1
4261 rts
4263 sounds_low: .byte <explosion_sound, <damage_sound, <item_sound, <key_sound, <note_sound, <emerge_sound
4264 sounds_high: .byte >explosion_sound, >damage_sound, >item_sound, >key_sound, >note_sound, >emerge_sound
4266 explosion_sound: .byte 1,0, 1,0, 60,0, 2,0
4267 damage_sound: .byte 1,0, 2,0, 40,0, 4,0
4268 item_sound: .byte $13,0, 3,0, 32,0, 3,0
4269 key_sound: .byte $13,0, 4,0, 50,0, 5,0
4270 note_sound: .byte $13,0, 241,255
4271 note_pitch: .byte 0,0
4272 note_duration: .byte 4,0
4273 emerge_sound: .byte 2,0, 3,0, 0,0, 2,0
4275 play_note: ; A=pitch, Y=duration
4277 sta note_pitch
4278 sty note_duration
4279 ldx #4
4280 ; Run on into the next routine.
4282 play_sound: ; X=sound number
4284 lda sounds_high,x
4285 tay
4286 lda sounds_low,x
4287 tax
4288 lda #7
4289 jsr $fff1
4291 rts
4293 copy_title_up:
4295 lda #$00
4296 sta $70
4297 lda #$18
4298 sta $71
4300 lda #$a0
4301 sta $72
4302 lda #$5a
4303 sta $73
4305 ldx #5
4306 ; Run on into the next routine.
4308 copy_title:
4310 copy_title_loop1:
4312 ldy #0
4313 copy_title_loop2:
4315 lda ($70),y
4316 sta ($72),y
4317 iny
4318 cpy #0
4319 bne copy_title_loop2
4321 clc
4322 lda $72
4323 adc #$40
4324 sta $72
4325 lda $73
4326 adc #$01
4327 sta $73
4328 clc
4330 lda $71
4331 adc #$01
4332 sta $71
4333 clc
4335 dex
4336 bpl copy_title_loop1
4338 rts
4340 copy_completed_screen_up:
4342 lda #$00
4343 sta $70
4344 lda #$0f
4345 sta $71
4347 lda #$60
4348 sta $72
4349 lda #$5e
4350 sta $73
4352 ldx #8
4353 jmp copy_title ; optimise away the rts
4355 init:
4356 jsr cls ; clear the text window
4358 lda #26 ; unset the text window
4359 jsr $ffee
4361 ; Define the default high scores.
4362 ldy #0
4363 lda #$80
4364 sta $70
4365 lda #$51
4366 sta $71
4367 lda #$16
4368 sta $72
4370 ldx #0
4371 init_define_high_scores_loop:
4373 lda #0
4374 sta ($70),y
4375 iny
4376 lda $72
4377 sta ($70),y
4378 iny
4379 lda #0
4380 sta ($70),y
4382 iny
4383 init_define_high_score_name_loop:
4385 lda high_score_default_name1,x
4386 sta ($70),y
4387 iny
4388 inx
4389 cpx #9
4390 beq init_define_high_scores_next
4391 cpx #18
4392 bne init_define_high_score_name_loop
4394 ldx #0
4395 init_define_high_scores_next:
4397 sed
4398 lda $72
4399 sec
4400 sbc #2
4401 sta $72
4402 cld
4403 clc
4405 cpy #96
4406 bne init_define_high_scores_loop
4408 ; Disable joystick support.
4409 lda #0
4410 sta $577e
4412 rts
4414 high_score_default_name1: .byte "RETRO "
4415 high_score_default_name2: .byte " SOFTWARE"
4417 title_vdu_bytes: .byte 17,2, 31,7,28, "to play"
4418 input_message: .byte 17,2, 31,2,27, "Press SPACE/FIRE"
4419 title_vdu_bytes1: .byte 17,3, 31,1,30, "Copyright (c) 2011"
4420 title_vdu_bytes2: .byte 17,3, 31,1,30, " David Boddie "
4421 title_vdu_bytes3: .byte 17,1, 31,1,30, "for Retro Software"
4422 title_vdu_bytes4: .byte 17,3, 31,1,30, "GNU GPL 3 or later"
4424 set_standard_palette:
4426 lda #1
4427 sta $70
4428 lda #1
4429 sta $71
4430 jsr set_palette
4432 jmp set_core_palette ; optimise away the rts
4434 complete_palette_bytes: .byte 2,4, 3,5, 1,4, 3,3, 2,2
4436 set_complete_palette:
4438 lda #0
4439 sta $80
4440 lda #25
4441 sta $81
4443 set_complete_palette_loop:
4445 jsr wait_for_vsync
4447 dec $81
4448 lda $81
4449 cmp #0
4450 bne set_complete_palette_loop
4452 lda #25
4453 sta $81
4455 ldx $80
4456 lda complete_palette_bytes,x
4457 sta $70
4458 inx
4459 lda complete_palette_bytes,x
4460 sta $71
4461 inx
4462 stx $80
4463 jsr set_palette
4465 lda $80
4466 cmp #10
4467 bne set_complete_palette_loop
4469 rts
4471 set_hidden_palette:
4473 lda #1
4474 sta $70
4475 lda #0
4476 sta $71
4477 jsr set_palette
4479 ; Run on into the next routine.
4481 set_core_palette:
4483 lda #2
4484 sta $70
4485 lda #2
4486 sta $71
4487 jsr set_palette
4489 lda #3
4490 sta $70
4491 lda #3
4492 sta $71
4493 jsr set_palette
4495 rts
4497 show_title:
4499 jsr set_standard_palette
4501 ldx #0
4502 write_title_text_loop:
4503 lda title_vdu_bytes,x
4504 jsr $ffee
4505 inx
4506 cpx #12
4507 bmi write_title_text_loop
4509 jsr show_input_message
4511 ; Show the title.
4512 jsr copy_title_up
4514 ; Show the high scores.
4516 jsr colour1
4518 lda #$80
4519 sta $70
4520 lda #$51
4521 sta $71
4523 lda #8
4524 sta $80
4526 show_title_high_scores_loop:
4528 lda #31
4529 jsr $ffee
4530 lda #2
4531 jsr $ffee
4532 lda $80
4533 adc #2
4534 sta $80
4535 clc
4536 jsr $ffee
4538 jsr write_score_digits
4540 lda #32
4541 jsr $ffee
4543 ldx #8
4544 ldy #3
4545 show_title_high_scores_vdu_loop2:
4547 lda ($70),y
4548 cmp #32
4549 bmi ignore_char
4550 cmp #123
4551 bpl ignore_char
4552 jsr $ffee
4554 ignore_char:
4555 iny
4556 dex
4557 bpl show_title_high_scores_vdu_loop2
4559 lda $70
4560 adc #12
4561 sta $70
4562 cmp #$e0
4563 bne show_title_high_scores_loop
4565 lda #0 ; message counter
4566 sta $72
4568 show_title_wait_loop:
4570 lda #150
4571 sta $5785
4573 ldx $72
4574 ldy #22
4575 show_title_wait_message_loop:
4577 lda title_vdu_bytes1,x
4578 jsr $ffee
4579 inx
4580 dey
4581 bpl show_title_wait_message_loop
4583 cpx #92
4584 beq show_title_wait_reset_offset
4586 txa
4587 sta $72
4588 jmp show_title_wait_inner_loop
4590 show_title_wait_reset_offset:
4591 lda #0
4592 sta $72
4594 show_title_wait_inner_loop:
4595 jsr wait_for_vsync
4597 dec $5785
4598 beq show_title_wait_loop
4600 show_title_wait_loop_no_update:
4601 lda #128
4602 ldx #0
4603 jsr $fff4
4604 cpx #0 ; fire button pressed?
4605 beq show_title_no_joystick
4607 lda #1 ; enable joystick support
4608 sta $577e
4609 jmp show_title_exit
4611 show_title_no_joystick:
4612 ldx #157 ; SPACE
4613 jsr check_key
4614 cpy #255
4615 bne show_title_wait_inner_loop
4617 lda #0 ; disable joystick support
4618 sta $577e
4620 show_title_exit:
4621 clc
4622 rts
4624 show_input_message:
4626 ldx #0
4627 show_input_message_loop:
4629 lda input_message,x
4630 jsr $ffee
4631 inx
4632 cpx #23
4633 bne show_input_message_loop
4635 rts
4637 wait_for_vsync:
4639 lda #19
4640 jmp $fff4 ; optimise away the rts
4642 game_over_vdu_bytes: .byte 28,4,17,15,15, 12, 26, 31,4,15, 17,2, "The journey", 31,9,17, "is over"
4644 delay:
4646 delay_loop:
4648 jsr wait_for_vsync
4649 dec $5785
4650 bne delay_loop
4652 rts
4654 show_game_over:
4656 lda #128
4657 sta $5785
4658 jsr delay
4660 ldx #0
4661 write_game_over_text_loop:
4662 lda game_over_vdu_bytes,x
4663 jsr $ffee
4664 inx
4665 cpx #33
4666 bmi write_game_over_text_loop
4668 lda #192
4669 sta $5785
4670 jsr delay
4672 rts
4674 end_of_level_bytes1: .byte 31,1,3, 17,3, "Exploration bonus", 31,11,5, "x 9"
4675 end_of_level_bytes2: .byte 31,0,28, 17,2, "My journey continues"
4677 show_end_of_level_screen:
4679 ; Draw a decorative room.
4681 jsr make_empty_room
4683 ldx #5
4684 end_of_level_h_walls_loop:
4686 lda #3
4687 sta $57b2,x
4688 sta $57e4,x
4689 dex
4690 bpl end_of_level_h_walls_loop
4692 ldx #30
4693 end_of_level_v_walls_loop:
4695 lda #3
4696 sta $57bc,x
4697 sta $57c1,x
4698 txa
4699 sec
4700 sbc #10
4701 tax
4702 bpl end_of_level_v_walls_loop
4704 jsr plot_room_tiles
4705 jsr set_standard_palette
4707 ldx #0
4708 end_of_level_text_loop1:
4710 lda end_of_level_bytes1,x
4711 jsr $ffee
4712 inx
4713 cpx #28
4714 bne end_of_level_text_loop1
4716 ; Count the number of rooms explored.
4717 ldx #0
4718 lda #0
4719 sta $8d
4720 sta $8e
4721 end_of_level_room_count_loop:
4723 lda $5200,x
4724 and #$80
4725 beq end_of_level_room_count_loop_next
4727 sed
4728 lda $8d
4729 adc #1
4730 sta $8d
4731 lda $8e
4732 adc #0
4733 sta $8e
4734 cld
4735 clc
4737 end_of_level_room_count_loop_next:
4738 inx
4739 cpx #121
4740 bne end_of_level_room_count_loop
4742 ; Position the player so that we can perform an animation.
4743 jsr position_player_set_up_plotting
4745 lda $8d
4746 sta $70
4747 lda $8e
4748 sta $71
4749 jsr write_bonus
4751 lda #0 ; reset motion counter
4752 sta $578e
4754 show_end_of_level_bonus_loop:
4756 jsr wait_for_vsync
4758 clc
4759 lda $578e
4760 and #15
4761 bne end_of_level_no_animation
4763 ; Animate the player.
4765 jsr reset_unplot_buffer
4766 jsr reset_plot_buffer
4768 ; $74,$75 should be unchanged
4769 jsr unplot_character
4771 lda $5281
4772 eor #1
4773 sta $5281
4774 jsr plot_character
4776 jsr plot_buffer
4778 end_of_level_no_animation:
4779 clc
4780 lda $578e
4781 and #3
4782 bne end_of_level_no_countdown
4784 ; Transfer the bonus to the score.
4786 sed
4787 sec
4788 lda $8d
4789 sbc #1
4790 sta $8d
4791 sta $70
4792 lda $8e
4793 sbc #0
4794 sta $8e
4795 sta $71
4796 cld
4797 clc
4799 jsr write_bonus
4801 lda #9
4802 sta $70
4803 jsr add_score
4805 lda $8d
4806 and #$3f
4807 asl
4808 ldy #1
4809 jsr play_note
4811 end_of_level_no_countdown:
4812 inc $578e ; update motion counter
4813 clc
4815 lda $8d
4816 cmp #0
4817 bne show_end_of_level_bonus_loop
4819 lda $8e
4820 cmp #0
4821 bne show_end_of_level_bonus_loop
4823 lda #64 ; initialise delay counter
4824 sta $5785
4825 jsr delay
4827 ldx #0
4828 end_of_level_text_loop2:
4830 lda end_of_level_bytes2,x
4831 jsr $ffee
4832 inx
4833 cpx #25
4834 bne end_of_level_text_loop2
4836 lda $578a
4837 cmp #3
4838 bpl show_end_of_level_screen_exit
4840 lda #192 ; initialise delay counter
4841 sta $5785
4842 jsr delay
4844 show_end_of_level_screen_exit:
4845 rts
4847 level_bonus_vdu_bytes: .byte 5,6,31, 1,17 ; reversed
4849 write_bonus: ; $70,$71=value
4850 ; $72,$73=address of VDU codes
4852 ldx #4
4853 write_bonus_vdu_bytes:
4855 lda level_bonus_vdu_bytes,x
4856 jsr $ffee
4857 dex
4858 bpl write_bonus_vdu_bytes
4860 ldy #1
4861 write_bonus_loop:
4863 tya
4864 tax ; temporary
4866 lda $70,x
4867 sta $80
4868 lsr
4869 lsr
4870 lsr
4871 lsr
4872 tax
4873 lda score_digits,x
4874 jsr $ffee
4876 lda $80
4877 and #$0f
4878 tax
4879 lda score_digits,x
4880 jsr $ffee
4882 dey
4883 bpl write_bonus_loop
4885 clc
4886 rts
4888 position_player_set_up_plotting:
4890 jsr reset_player_position
4891 jsr remove_characters
4893 jsr reset_unplot_buffer
4894 jsr reset_plot_buffer
4896 ; Run on into the next routine.
4898 plot_the_player:
4900 lda #$80 ; plot the player
4901 sta $74
4902 lda #$52
4903 sta $75
4904 jsr plot_character
4906 jsr plot_buffer
4907 rts
4909 complete_game_vdu_bytes1: .byte 12
4910 complete_game_vdu_bytes2: .byte 17,3, 31,2,20, "Congratulations!"
4911 complete_game_vdu_bytes3: .byte 17,2, 31,1,22, "Now journey onward"
4912 complete_game_vdu_bytes4: .byte 17,2, 31,1,24, "to a new adventure"
4914 show_complete_game:
4916 jsr blank_screen
4918 ldx #0
4919 show_complete_game_vdu_loop:
4921 lda complete_game_vdu_bytes1,x
4922 jsr $ffee
4923 inx
4924 cpx #68
4925 bne show_complete_game_vdu_loop
4927 jsr copy_completed_screen_up
4929 jsr set_complete_palette
4931 lda #255
4932 sta $5785
4934 show_complete_game_delay_loop:
4936 jsr wait_for_vsync
4938 dec $5785
4939 bne show_complete_game_no_message
4941 jsr colour1
4942 jsr show_input_message
4944 show_complete_game_no_message:
4946 lda #128
4947 ldx #0
4948 jsr $fff4
4949 cpx #0 ; fire button pressed?
4950 beq show_complete_game_no_joystick
4951 jmp show_complete_game_exit
4953 show_complete_game_no_joystick:
4955 ldx #157
4956 jsr check_key
4957 cpy #255
4958 bne show_complete_game_delay_loop
4960 show_complete_game_exit:
4961 clc
4962 rts
4964 check_high_scores:
4966 ; Start at the bottom of the table, moving scores down as necessary, and
4967 ; write in the current score at the appropriate place.
4969 lda #$86 ; current score
4970 sta $70
4971 lda #$57
4972 sta $71
4974 lda #$80
4975 sta $72
4976 lda #$51
4977 sta $73
4979 check_high_scores_loop:
4981 ldy #2
4982 check_high_scores_digits_loop:
4984 lda ($72),y
4985 cmp ($70),y ; existing score less than current score?
4986 bmi check_high_scores_move_down
4987 beq check_high_scores_digits_next ; keep checking digits if equal
4988 jmp check_high_scores_next
4990 check_high_scores_digits_next:
4991 dey
4992 bpl check_high_scores_digits_loop
4994 check_high_scores_next:
4995 clc
4996 lda $72
4997 adc #12
4998 sta $72
4999 cmp #$e0
5000 bne check_high_scores_loop
5002 ; The player's score didn't make it into the high score table.
5003 rts
5005 check_high_scores_move_down: ; $70,$71=pointer to current score
5006 ; $72,$73=pointer to old score
5008 ; The current score exceeded the existing entry. Make a note of the
5009 ; position in the high score table, insert the player's score, and take
5010 ; the old score
5012 lda $72 ; Record the position in the high score table of the
5013 sta $8d ; player's score.
5014 lda $73
5015 sta $8e
5017 lda #$e0
5018 sta $74
5019 lda #$51
5020 sta $75
5022 ldy #0
5023 insert_blank_player_name_loop:
5025 cpy #3
5026 bpl insert_blank_player_name_score_only
5028 lda ($70),y
5029 jmp insert_blank_player_name_store
5031 insert_blank_player_name_score_only:
5032 lda #32
5034 insert_blank_player_name_store:
5035 sta ($74),y
5036 iny
5037 cpy #12
5038 bne insert_blank_player_name_loop
5040 check_high_scores_move_down_loop:
5042 ldy #0
5043 check_high_scores_copy_score_and_name:
5045 lda ($72),y ; swap the current score with the score in the table
5046 tax
5047 lda ($74),y
5048 sta ($72),y
5049 txa
5050 sta ($74),y
5051 iny
5052 cpy #12
5053 bne check_high_scores_copy_score_and_name
5055 clc
5056 lda $72
5057 adc #12
5058 sta $72
5059 cmp #$e0
5060 bne check_high_scores_move_down_loop
5062 ; Draw a decorative room.
5064 jsr set_hidden_palette
5066 jsr make_empty_room
5068 lda #3
5069 sta $76
5070 sta $77
5071 jsr draw_top_line
5072 jsr draw_bottom_line
5073 jsr draw_left_line
5075 lda #0
5076 sta $77
5077 jsr draw_right_line
5079 jsr plot_room_tiles
5081 ; Add text characters to the room.
5082 jsr colour3
5084 lda #3 ; x
5085 sta $70
5086 lda #6 ; y
5087 sta $71
5089 lda #65
5090 sta $72
5092 ldx #3
5093 plot_text_characters_loop:
5095 jsr print_xy
5097 lda $70
5098 adc #4
5099 sta $70
5101 dex
5102 bpl plot_text_characters_next
5104 lda #3
5105 sta $70
5106 lda $71
5107 adc #3
5108 sta $71
5110 ldx #3
5112 plot_text_characters_next:
5114 inc $72
5115 lda $72
5116 cmp #91
5117 bne plot_text_characters_loop
5119 lda #11
5120 sta $70
5121 lda #95 ; _ representing a space
5122 sta $72
5123 jsr print_xy
5125 lda #15
5126 sta $70
5127 lda #60 ; < representing delete
5128 sta $72
5129 jsr print_xy
5131 ; Put the player in the centre of the room.
5132 jsr position_player_set_up_plotting
5134 lda #0 ; reset motion counter
5135 sta $578e
5137 lda #0 ; not on a character
5138 sta $578d
5140 lda #0 ; reset the level number so that the correct tiles are used
5141 sta $578a
5143 lda #3 ; cursor position in the high score entry held in $8d,$8e
5144 sta $8f
5146 jsr set_standard_palette
5148 ldx #0
5149 high_score_vdu_loop:
5151 lda high_score_vdu_bytes,x
5152 jsr $ffee
5153 inx
5154 cpx #39
5155 bne high_score_vdu_loop
5157 high_score_entry_loop:
5159 jsr reset_unplot_buffer
5160 jsr reset_plot_buffer
5162 jsr move_player
5163 ; Check if the player leaves the room.
5164 bcc high_score_entry_check_position
5165 jmp high_score_entry_after_loop
5167 high_score_entry_check_position:
5169 lda $5285 ; dx
5170 cmp #2
5171 beq high_score_entry_maybe_aligned
5172 jmp high_score_entry_not_aligned
5174 high_score_entry_maybe_aligned:
5176 lda $5282 ; y
5177 tay
5178 cmp #8
5179 bpl high_score_entry_not_aligned
5181 lda $5284 ; x
5182 tax
5183 cmp #9
5184 beq high_score_entry_not_aligned
5185 and #1
5186 beq high_score_entry_not_aligned
5188 lda $5283 ; dy
5189 cmp #2
5190 bmi high_score_entry_aligned
5191 jmp high_score_entry_not_aligned
5193 lda $5282 ; y again (don't apply the touching rule to the bottom
5194 cmp #7 ; row of characters)
5195 beq high_score_entry_not_aligned
5197 iny ; we are really touching the character below
5199 high_score_entry_aligned:
5201 lda $578d
5202 cmp #1
5203 beq high_score_entry_next
5205 ; The player is aligned with a letter.
5206 txa
5207 sec
5208 sbc #1
5209 lsr
5210 sta $7e ; record (x - 1) / 2
5212 tya ; recall y
5213 sec
5214 sbc #1
5215 asl
5216 asl ; (y - 1) * 4
5217 clc
5219 adc $7e ; (y - 1) * 4 + (x - 1) / 2
5220 adc #65
5221 sta $7e ; record the ASCII code
5223 cmp #91
5224 bmi insert_character
5226 cmp #92
5227 beq delete_character
5229 ; Insert a space.
5230 lda #32
5231 sta $7e
5233 insert_character:
5234 lda $8f
5235 cmp #12
5236 bpl high_score_entry_pressed
5238 tay ; insert the character
5239 lda $7e
5240 sta ($8d),y
5241 jsr print_high_score_character
5243 inc $8f
5244 jmp high_score_entry_pressed
5246 delete_character:
5247 lda $8f
5248 cmp #4
5249 bmi high_score_entry_pressed
5251 cmp #12
5252 beq high_score_delete_previous_character
5254 tay
5255 lda #32 ; insert a space
5256 sta ($8d),y
5257 jsr print_high_score_character
5259 high_score_delete_previous_character:
5260 dec $8f
5261 lda $8f
5262 tay ; insert a space
5263 lda #32
5264 sta ($8d),y
5265 jsr print_high_score_character
5267 high_score_entry_pressed:
5268 lda #1
5269 sta $578d
5270 jmp high_score_entry_next
5272 high_score_entry_not_aligned:
5273 lda #0
5274 sta $578d
5276 high_score_entry_next:
5278 jsr wait_for_vsync
5279 jsr plot_buffer
5281 jmp high_score_entry_loop
5283 inc $578e
5284 clc
5286 high_score_entry_after_loop:
5287 clc
5289 jsr cls
5290 jsr set_hidden_palette
5292 rts
5294 high_score_vdu_bytes: .byte 17,1, 31,2,3, "Enter your name!", 17,3, 31,5,30, "> <", 17,1
5296 cls:
5297 lda #12
5298 jsr $ffee
5299 rts
5301 colour1:
5302 lda #17
5303 jsr $ffee
5304 lda #1
5305 jsr $ffee
5306 rts
5308 colour3:
5309 lda #17
5310 jsr $ffee
5311 lda #3
5312 jsr $ffee
5313 rts
5315 print_high_score_character: ; A=ASCII code
5317 clc
5318 sta $72 ; store the character
5319 lda $8f
5320 adc #3
5321 sta $70 ; store the x position of the character
5322 lda #30
5323 sta $71
5324 ; Run on into the next routine.
5326 print_xy:
5328 lda #31
5329 jsr $ffee
5330 lda $70
5331 jsr $ffee
5332 lda $71
5333 jsr $ffee
5334 lda $72
5335 jsr $ffee
5336 rts
5338 disable_sound: ; X=1 (disable); X=0 (enable)
5340 lda #210
5341 ldy #0
5342 jmp $fff4 ; optimise away the rts
5344 status_vdu_bytes: .byte 31,2,0, 17,3, "Score", 31,11,0, 17,2, "Strength", 17,1
5345 ; TAB(1,0), COLOUR 3, "Score", TAB(12,0), COLOUR 2, "Strength", COLOUR 1
5347 start_new_game:
5349 ; Clear the screen.
5350 jsr cls
5352 ; Set the level.
5353 lda #0
5354 sta $578a
5356 ; Set the score.
5357 lda #0
5358 sta $5786
5359 lda #0
5360 sta $5787
5361 lda #0
5362 sta $5788
5364 ; Blank the screen now because it will be blanked before the room is shown
5365 ; and otherwise the strength bar will show briefly.
5366 jsr blank_screen
5368 ; Set the player's strength.
5369 lda #0
5370 sta $5784
5371 lda #64
5372 sta $70
5373 jsr add_strength
5375 ; Set the projectile type.
5376 lda #0
5377 sta $5789
5379 rts
5381 reset_player_position:
5383 lda #1 ; player
5384 sta $5280
5385 lda #6 ; down (first frame)
5386 sta $5281
5387 lda #4 ; y=4
5388 sta $5282
5389 lda #2 ; dy=2
5390 sta $5283
5391 lda #4 ; x=4
5392 sta $5284
5393 lda #3 ; dx=3
5394 sta $5285
5396 rts
5398 start_level:
5400 ; Clear the item/player flags.
5401 lda #0
5402 sta $5780
5404 ; Set current room.
5406 ldx $578a
5407 lda start_rooms_y,x
5408 sta $5782
5409 lda start_rooms_x,x
5410 sta $5783
5412 ; Set the player's position.
5414 jsr reset_player_position
5416 ; Reset the weapon counter.
5417 lda #0
5418 sta $577f
5420 ; Fill the treasure table with objects.
5421 ldx $578a ; level
5422 lda key_rooms,x
5423 sta $80
5425 ldx $578a ; level
5426 lda seeds,x
5427 adc #1
5428 and #31
5429 sta $7c
5430 clc
5431 lda seeds,x
5432 adc #2
5433 and #31
5434 sta $7d
5435 clc
5437 lda $578a ; create an upper limit on the weapon type found in this level
5438 adc #2
5439 sta $5781
5440 clc
5442 lda #$00
5443 sta $8e
5444 lda #$52
5445 sta $8f
5447 ldy #0
5448 start_level_add_treasure_loop:
5450 cpy $80 ; check for the key room
5451 bne start_level_add_treasure_item
5453 lda #5 ; the value to store is type + 1
5454 jmp start_level_add_treasure_store
5456 start_level_add_treasure_item:
5457 clc
5458 jsr unlimited_values
5459 and #$0f
5460 cmp #0
5461 beq start_level_add_treasure_none
5463 clc
5464 sta $8c
5465 tya
5466 adc $8c
5467 and #31
5468 clc
5469 tax
5470 lda treasure_table,x
5472 cmp #4
5473 bmi start_level_add_treasure_weapon
5475 clc
5476 adc #1
5477 jmp start_level_add_treasure_store
5479 start_level_add_treasure_weapon:
5481 ; Only add weapons with types that equal the level number or exceed it
5482 ; by one.
5483 cmp $5781
5484 bcs start_level_add_treasure_none
5486 clc
5487 adc #1 ; store values 0-8 as values 1-9
5488 jmp start_level_add_treasure_store
5490 start_level_add_treasure_none:
5491 clc
5492 lda #0 ; do not put treasure in this room
5494 start_level_add_treasure_store:
5495 clc
5496 sta ($8e),y ; add the item to the table
5498 iny
5499 cpy #121
5500 bmi start_level_add_treasure_loop
5502 ; Write the status text.
5503 ldx #0
5504 write_status_text_loop:
5505 lda status_vdu_bytes,x
5506 jsr $ffee
5507 inx
5508 cpx #25
5509 bmi write_status_text_loop
5511 jsr write_score
5513 clc
5514 rts
5516 main:
5517 jsr init
5519 main_loop:
5521 jsr show_title
5523 jsr start_new_game
5525 level_loop:
5527 jsr start_level
5529 game_loop:
5531 jsr remove_characters
5533 jsr reset_unplot_buffer
5534 jsr reset_plot_buffer
5536 lda $5782 ; current room (y)
5537 sta $78
5538 lda $5783 ; current room (x)
5539 sta $79
5540 jsr plot_room
5541 jsr set_room_palette
5542 jsr create_enemy_positions
5543 jsr add_treasure
5545 jsr plot_the_player
5547 lda #0 ; reset projectile counter
5548 sta $578d
5550 lda #0 ; reset motion counter
5551 sta $578e
5553 lda #63 ; reset generation counter
5554 sta $578f
5556 room_loop:
5557 jsr reset_unplot_buffer
5558 jsr reset_plot_buffer
5560 jsr move_characters
5561 jsr move_projectile
5563 lda $5780 ; is player out of strength ($40), leaving the
5564 and #$c2 ; level (0x80) or completing the game (0x02)?
5565 beq room_loop_player_move
5566 clc
5568 dec $5785 ; leave the loop when the delay
5569 bne room_loop_delay_next
5570 jmp after_room_loop ; counter is about to reset
5572 room_loop_delay_next:
5574 lda $5281 ; leave the loop when the player demise
5575 cmp #11 ; animation has finished
5576 beq room_loop_after_player_move
5577 clc
5579 lda $578e
5580 and #7
5581 bne room_loop_after_player_move
5583 lda $5780 ; skip the animation if leaving the level or
5584 and #$82 ; completing the game
5585 bne room_loop_after_player_move
5587 ; Show the demise animation when appropriate.
5589 lda #$80
5590 sta $74
5591 lda #$52
5592 sta $75
5594 jsr unplot_character
5596 inc $5281
5597 jsr plot_character
5598 jmp room_loop_after_player_move
5600 room_loop_player_move:
5602 ; See if it is time to generate a new enemy.
5603 lda $578f
5604 cmp #0
5605 bne no_emerge_characters
5606 jsr emerge_characters
5608 no_emerge_characters:
5609 clc
5611 jsr check_fire_key
5612 jsr move_player
5613 bcs after_room_loop ; check if we are leaving the level
5615 room_loop_after_player_move:
5616 clc
5618 lda #19
5619 jsr $fff4
5620 jsr plot_buffer
5622 ldx #143 ; Escape key check
5623 jsr check_key
5624 cpy #255
5625 beq main_loop_play_again
5627 ldx #174 ; S key check
5628 jsr check_key
5629 cpy #255
5630 bne no_set_sound
5632 ldx #0
5633 jsr disable_sound
5634 jmp after_sound_checks
5636 no_set_sound:
5638 ldx #239 ; Q key check
5639 jsr check_key
5640 cpy #255
5641 bne after_sound_checks
5643 ldx #1
5644 jsr disable_sound
5646 after_sound_checks:
5648 ldx #200 ; P key check
5649 jsr check_key
5650 cpy #255
5651 bne no_pause
5653 pause_loop:
5655 ldx #201 ; O key check
5656 jsr check_key
5657 cpy #255
5658 bne pause_loop
5660 no_pause:
5661 clc
5663 lda $578d
5664 cmp #0
5665 beq room_loop_no_update_projectile_counter
5667 dec $578d
5669 room_loop_no_update_projectile_counter:
5671 dec $578f ; update generation counter
5673 inc $578e ; update motion counter
5674 clc
5675 jmp room_loop
5677 after_room_loop:
5678 clc
5680 lda $5780
5681 and #$80
5682 bne exit_level
5684 lda $5780
5685 and #$40
5686 bne game_over
5688 lda $5780
5689 and #$02
5690 bne complete_game
5692 jmp game_loop
5694 exit_level:
5696 jsr show_end_of_level_screen
5698 inc $578a
5699 clc
5700 jmp level_loop
5702 game_over:
5703 jsr show_game_over
5704 jmp main_loop_play_again
5706 complete_game:
5707 jsr show_end_of_level_screen
5708 jsr show_complete_game
5709 jmp main_loop_play_again
5711 main_loop_play_again:
5712 jsr cls
5714 ; Check the score against the high scores.
5715 jsr check_high_scores
5717 jmp main_loop
5719 exit:
5720 clc
5721 rts