784 lines
14 KiB
NASM
784 lines
14 KiB
NASM
; -----------------------------------------------------------
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; play.asm - the game: a fresh maze is carved with a
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; recursive backtracker every round, player 1 (joystick 2)
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; runs the corridors toward the exit diamond, player 2
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; (joystick 1) rides the wall corners and fire spins the
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; four wall pieces around the cursor by 90 degrees; the
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; roaming colored enemies end the round on touch
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;
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; screen layout: status on row 0, the 39x23 maze lattice on
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; rows 1-23 (cells = odd col / even row, posts = even col /
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; odd row, wall slots = the rest), a hint line on row 24
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; -----------------------------------------------------------
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play_init:
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jsr clear_screen
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+prtext 0, 0, WHITE, txt_title, 9
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+prtext 0, 28, LGREY, txt_goal, txt_goale-txt_goal
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+prtext 24, 6, DGREY, txt_hint, txt_hinte-txt_hint
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; fill the whole lattice with wall blocks
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ldx #1
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pi_fillrow:
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stx ptmp
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jsr row_ptr
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ldy #38
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pi_fillcol:
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lda #CH_WALL
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sta (scrlo),y
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lda #COL_WALL
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sta (collo),y
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dey
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bpl pi_fillcol
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ldx ptmp
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inx
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cpx #24
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bne pi_fillrow
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; the pivot posts get their own darker shade
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ldx #1 ; post rows 1, 3, ... 23
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pi_postrow:
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stx ptmp
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jsr row_ptr
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ldy #38 ; post columns 38, 36, ... 0
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pi_postcol:
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lda #COL_POST
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sta (collo),y
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dey
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dey
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bpl pi_postcol
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ldx ptmp
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inx
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inx
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cpx #25
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bcc pi_postrow
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; carve the maze
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ldx #0
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lda #0
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pi_clrv:
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sta visited,x
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inx
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cpx #NCELLS
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bne pi_clrv
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jsr gen_maze
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; the exit: a green diamond in the right border wall
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pi_exit:
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jsr rand8
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and #$0f
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cmp #MAZE_CH
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bcs pi_exit
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asl ; cell row -> screen row
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clc
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adc #2
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sta exrow
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tax
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jsr row_ptr
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ldy #38
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lda #CH_EXIT
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sta (scrlo),y
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lda #COL_EXIT
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sta (collo),y
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; the runner starts in the top-left cell
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lda #1
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sta px
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lda #2
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sta py
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jsr draw_player
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; the corner cursor starts on the center post
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lda #18
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sta kx
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lda #11
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sta ky
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jsr spawn_enemies
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; input state: a fire still held from the previous screen
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; must be released before it can spin walls
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lda #0
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sta rheld
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sta cheld
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sta endflag
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lda #1
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sta cfheld
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+setupd play_update
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rts
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; ============================================================
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; maze generation - recursive backtracker over the 19x11
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; cells; the screen itself is the wall data structure
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; ============================================================
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gen_maze:
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lda #0
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sta gcx
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sta gcy
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sta gsp
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jsr gv_mark
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jsr carve_cell
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gm_loop:
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; collect the unvisited neighbor directions
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lda #0
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sta gn
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ldx #0
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gm_scan:
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stx gtd
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lda gcx
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clc
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adc dxtab,x
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sta gnx
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cmp #MAZE_CW ; unsigned: -1 wraps to $ff and fails too
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bcs gm_next
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ldx gtd
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lda gcy
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clc
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adc dytab,x
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sta gny
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cmp #MAZE_CH
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bcs gm_next
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ldx gny
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lda mul19,x
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clc
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adc gnx
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tax
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lda visited,x
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bne gm_next
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ldx gn
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lda gtd
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sta gdlist,x
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inc gn
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gm_next:
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ldx gtd
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inx
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cpx #4
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bne gm_scan
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lda gn
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beq gm_pop
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; pick a random one of them
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gm_pick:
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jsr rand8
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and #3
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cmp gn
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bcs gm_pick
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tax
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lda gdlist,x
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sta gtd
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; push the current cell, open the wall, step through it
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ldx gsp
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lda gcx
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sta stackx,x
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lda gcy
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sta stacky,x
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inc gsp
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jsr carve_wall
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ldx gtd
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lda gcx
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clc
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adc dxtab,x
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sta gcx
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ldx gtd
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lda gcy
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clc
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adc dytab,x
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sta gcy
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jsr gv_mark
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jsr carve_cell
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jmp gm_loop
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gm_pop:
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; dead end: back up; empty stack = the maze is done
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lda gsp
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beq gm_done
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dec gsp
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ldx gsp
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lda stackx,x
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sta gcx
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lda stacky,x
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sta gcy
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jmp gm_loop
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gm_done:
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rts
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gv_mark: ; visited[gcy * 19 + gcx] = 1
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ldx gcy
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lda mul19,x
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clc
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adc gcx
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tax
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lda #1
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sta visited,x
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rts
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carve_cell: ; open the cell (2*gcx+1, 2*gcy+2)
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lda gcy
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asl
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clc
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adc #2
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tax
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jsr row_ptr
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lda gcx
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asl
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clc
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adc #1
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tay
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lda #CH_FLOOR
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sta (scrlo),y
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lda #BLACK
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sta (collo),y
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rts
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carve_wall: ; open the wall slot toward direction gtd
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ldx gtd
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lda gcy
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asl
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clc
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adc #2
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clc
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adc dytab,x
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tax
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jsr row_ptr
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ldx gtd
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lda gcx
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asl
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clc
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adc #1
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clc
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adc dxtab,x
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tay
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lda #CH_FLOOR
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sta (scrlo),y
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lda #BLACK
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sta (collo),y
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rts
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dxtab: !byte 0, 0, $ff, 1 ; up, down, left, right
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dytab: !byte $ff, 1, 0, 0
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mul19: !byte 0, 19, 38, 57, 76, 95, 114, 133, 152, 171, 190
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; ---- enemies: random colors, random right-half cells ----
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spawn_enemies:
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lda #0
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sta ei
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sn_loop:
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sn_rx:
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jsr rand8
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and #$0f
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cmp #MAZE_CH
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bcs sn_rx
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clc
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adc #MAZE_CW-MAZE_CH ; cell column 8-18: away from the runner
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asl
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clc
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adc #1
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sta gnx ; candidate screen column
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sn_ry:
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jsr rand8
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and #$0f
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cmp #MAZE_CH
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bcs sn_ry
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asl
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clc
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adc #2
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sta gny ; candidate screen row
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ldx gny
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jsr row_ptr
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ldy gnx
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lda (scrlo),y
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cmp #CH_FLOOR ; only an empty cell will do
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bne sn_rx
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lda #CH_ENEMY
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sta (scrlo),y
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jsr rand8
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and #7
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tax
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lda ecoltab,x
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sta (collo),y
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ldx ei
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sta ecol,x
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lda gnx
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sta ex,x
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lda gny
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sta ey,x
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jsr rand8
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and #3
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sta edir,x
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inc ei
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lda ei
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cmp #NENEMIES
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bne sn_loop
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rts
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ecoltab: ; anything but the white runner / grey walls
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!byte RED, CYAN, PURPLE, YELLOW, ORANGE, LRED, LBLUE, BLUE
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; ============================================================
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; one frame of play
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; ============================================================
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play_update:
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jsr upd_runner
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lda endflag
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bne pu_end
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jsr upd_enemies
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lda endflag
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bne pu_end
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jsr upd_cursor
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jsr upd_flash
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rts
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pu_end:
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cmp #1
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beq pu_win
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lda #SFX_LOSE
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jsr sfx_play
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jmp lose_init ; its rts returns to the main loop
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pu_win:
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lda #SFX_WIN
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jsr sfx_play
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jmp win_init
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; ---- player 1: walk the corridors, one char per step ----
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upd_runner:
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jsr read_joy
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and #$0f
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sta rdir
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bne ur_held
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lda #0
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sta rheld
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rts
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ur_held:
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lda rheld
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beq ur_first
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dec rtimer
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beq ur_rep
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rts
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ur_rep:
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lda #REP_PERIOD
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sta rtimer
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jmp ur_move
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ur_first:
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lda #1
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sta rheld
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lda #REP_HOLD
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sta rtimer
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ur_move:
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ldx px
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ldy py
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lda rdir
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lsr
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bcs ur_up
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lsr
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bcs ur_down
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lsr
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bcs ur_left
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inx ; right
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jmp ur_try
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ur_up:
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dey
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jmp ur_try
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ur_down:
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iny
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jmp ur_try
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ur_left:
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dex
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ur_try:
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stx ttx
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sty tty
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ldx tty
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jsr row_ptr
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ldy ttx
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lda (scrlo),y
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cmp #CH_FLOOR
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beq ur_go
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cmp #CH_EXIT
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beq ur_win
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cmp #CH_ENEMY
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beq ur_dead
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rts ; a wall: blocked
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ur_go:
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ldx py
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jsr row_ptr
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ldy px
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lda #CH_FLOOR
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sta (scrlo),y
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lda #BLACK
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sta (collo),y
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lda ttx
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sta px
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lda tty
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sta py
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jmp draw_player
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ur_win:
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lda #1
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sta endflag
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rts
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ur_dead:
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lda #2
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sta endflag
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rts
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draw_player:
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ldx py
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jsr row_ptr
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ldy px
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lda #CH_PLAYER
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sta (scrlo),y
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lda #WHITE
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sta (collo),y
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rts
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; ---- player 2: the corner cursor + the wall spin ----
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upd_cursor:
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jsr read_joy2
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sta j2bits
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and #$0f
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sta cdir
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bne uc_held
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lda #0
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sta cheld
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jmp uc_fire
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uc_held:
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lda cheld
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beq uc_first
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dec ctimer
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beq uc_rep
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jmp uc_fire
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uc_rep:
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lda #CREP_PERIOD
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sta ctimer
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jmp uc_move
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uc_first:
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lda #1
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sta cheld
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lda #CREP_HOLD
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sta ctimer
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uc_move:
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ldx kx
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ldy ky
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lda cdir
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lsr
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bcs uc_up
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lsr
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bcs uc_down
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lsr
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bcs uc_left
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cpx #36 ; right: interior posts end at column 36
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bcs uc_fire
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inx
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inx
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jmp uc_go
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uc_up:
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cpy #4 ; top interior post row is 3
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bcc uc_fire
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dey
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dey
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jmp uc_go
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uc_down:
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cpy #21 ; bottom interior post row is 21
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bcs uc_fire
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iny
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iny
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jmp uc_go
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uc_left:
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cpx #3 ; left interior post column is 2
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bcc uc_fire
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dex
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dex
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uc_go:
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stx ttx
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sty tty
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ldx ky ; the old post gets its color back
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jsr row_ptr
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ldy kx
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lda #COL_POST
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sta (collo),y
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lda ttx
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sta kx
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lda tty
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sta ky
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lda #SFX_CURSOR
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jsr sfx_play
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uc_fire:
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lda j2bits
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and #JOY_FIRE
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beq uc_frel
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lda cfheld
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bne uc_done
|
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lda #1
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sta cfheld
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jmp do_rotate ; its rts returns to play_update's caller
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uc_frel:
|
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lda #0
|
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sta cfheld
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uc_done:
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rts
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|
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; ---- spin the four wall slots around post (kx, ky) by 90
|
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; degrees clockwise; denied while anyone stands in them ----
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do_rotate:
|
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ldx ky ; gather the four slot chars
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|
dex
|
|
jsr row_ptr
|
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ldy kx
|
|
lda (scrlo),y
|
|
sta nch
|
|
ldx ky
|
|
inx
|
|
jsr row_ptr
|
|
ldy kx
|
|
lda (scrlo),y
|
|
sta sch
|
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ldx ky
|
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jsr row_ptr
|
|
ldy kx
|
|
dey
|
|
lda (scrlo),y
|
|
sta wch
|
|
iny
|
|
iny
|
|
lda (scrlo),y
|
|
sta ech
|
|
; every slot must be plain wall or floor
|
|
lda nch
|
|
jsr rot_ok
|
|
bcs rot_deny
|
|
lda sch
|
|
jsr rot_ok
|
|
bcs rot_deny
|
|
lda wch
|
|
jsr rot_ok
|
|
bcs rot_deny
|
|
lda ech
|
|
jsr rot_ok
|
|
bcs rot_deny
|
|
; clockwise: north<-west, east<-north, south<-east, west<-south
|
|
ldx ky
|
|
dex
|
|
jsr row_ptr
|
|
ldy kx
|
|
lda wch
|
|
jsr put_slot
|
|
ldx ky
|
|
inx
|
|
jsr row_ptr
|
|
ldy kx
|
|
lda ech
|
|
jsr put_slot
|
|
ldx ky
|
|
jsr row_ptr
|
|
ldy kx
|
|
dey
|
|
lda sch
|
|
jsr put_slot
|
|
iny
|
|
iny
|
|
lda nch
|
|
jsr put_slot
|
|
lda #SFX_ROTATE
|
|
jmp sfx_play
|
|
rot_deny:
|
|
lda #SFX_DENY
|
|
jmp sfx_play
|
|
|
|
rot_ok: ; C clear when A is spinnable (wall or floor)
|
|
cmp #CH_WALL
|
|
beq ro_yes
|
|
cmp #CH_FLOOR
|
|
beq ro_yes
|
|
sec
|
|
rts
|
|
ro_yes:
|
|
clc
|
|
rts
|
|
|
|
put_slot: ; write char A at (scrlo),y + matching color
|
|
sta (scrlo),y
|
|
cmp #CH_WALL
|
|
beq ps_wall
|
|
lda #BLACK
|
|
sta (collo),y
|
|
rts
|
|
ps_wall:
|
|
lda #COL_WALL
|
|
sta (collo),y
|
|
rts
|
|
|
|
; ---- the enemies: staggered random walkers ----
|
|
upd_enemies:
|
|
lda #0
|
|
sta ei
|
|
ue_loop:
|
|
ldx ei
|
|
lda framectr
|
|
clc
|
|
adc estag,x
|
|
and #7 ; each enemy steps every 8th frame
|
|
bne ue_next
|
|
jsr enemy_step
|
|
lda endflag
|
|
bne ue_out
|
|
ue_next:
|
|
inc ei
|
|
lda ei
|
|
cmp #NENEMIES
|
|
bne ue_loop
|
|
ue_out:
|
|
rts
|
|
|
|
estag: !byte 0, 2, 4, 6
|
|
|
|
enemy_step:
|
|
jsr rand8 ; 1 in 4: wander off in a new direction
|
|
and #3
|
|
beq es_newdir
|
|
ldx ei
|
|
lda edir,x
|
|
jsr etry_dir
|
|
bcc es_done
|
|
es_newdir:
|
|
lda #8
|
|
sta etries
|
|
es_pick:
|
|
jsr rand8
|
|
and #3
|
|
jsr etry_dir
|
|
bcc es_done
|
|
dec etries ; walled in on all sides: sit this one out
|
|
bne es_pick
|
|
es_done:
|
|
rts
|
|
|
|
etry_dir: ; A = direction; C clear when it moved (or won)
|
|
sta etd
|
|
tax
|
|
ldy ei
|
|
lda ex,y
|
|
clc
|
|
adc dxtab,x
|
|
sta ttx
|
|
lda ey,y
|
|
clc
|
|
adc dytab,x
|
|
sta tty
|
|
ldx tty
|
|
jsr row_ptr
|
|
ldy ttx
|
|
lda (scrlo),y
|
|
cmp #CH_FLOOR
|
|
beq ed_move
|
|
cmp #CH_PLAYER
|
|
beq ed_kill
|
|
sec ; wall, exit or another enemy: blocked
|
|
rts
|
|
ed_kill:
|
|
lda #2
|
|
sta endflag
|
|
clc
|
|
rts
|
|
ed_move:
|
|
ldx ei
|
|
lda ey,x
|
|
sta gny ; old position
|
|
lda ex,x
|
|
sta gnx
|
|
lda ttx
|
|
sta ex,x
|
|
lda tty
|
|
sta ey,x
|
|
lda etd
|
|
sta edir,x
|
|
ldx gny ; erase the old cell
|
|
jsr row_ptr
|
|
ldy gnx
|
|
lda #CH_FLOOR
|
|
sta (scrlo),y
|
|
lda #BLACK
|
|
sta (collo),y
|
|
ldx tty ; draw at the new one
|
|
jsr row_ptr
|
|
ldy ttx
|
|
lda #CH_ENEMY
|
|
sta (scrlo),y
|
|
ldx ei
|
|
lda ecol,x
|
|
sta (collo),y
|
|
clc
|
|
rts
|
|
|
|
; ---- per-frame flashes: the exit blinks, the cursor pulses ----
|
|
upd_flash:
|
|
ldx exrow
|
|
jsr row_ptr
|
|
ldy #38
|
|
lda framectr
|
|
and #8
|
|
bne uf_exw
|
|
lda #COL_EXIT
|
|
jmp uf_exset
|
|
uf_exw:
|
|
lda #WHITE
|
|
uf_exset:
|
|
sta (collo),y
|
|
ldx ky
|
|
jsr row_ptr
|
|
ldy kx
|
|
lda framectr
|
|
and #4
|
|
bne uf_cred
|
|
lda #YELLOW
|
|
jmp uf_cset
|
|
uf_cred:
|
|
lda #RED
|
|
uf_cset:
|
|
sta (collo),y
|
|
rts
|
|
|
|
; ---- play texts ----
|
|
txt_goal: !scr "reach the "
|
|
!byte CH_EXIT
|
|
txt_goale:
|
|
txt_hint: !scr "p1: joy2/wasd p2: joy1/ijkl"
|
|
txt_hinte:
|
|
|
|
; ---- play variables ----
|
|
px: !byte 0 ; runner position (screen col / row)
|
|
py: !byte 0
|
|
kx: !byte 0 ; corner cursor position (post col / row)
|
|
ky: !byte 0
|
|
exrow: !byte 0 ; screen row of the exit diamond
|
|
endflag: !byte 0 ; 0 = playing, 1 = escaped, 2 = caught
|
|
rheld: !byte 0 ; runner direction repeat state
|
|
rtimer: !byte 0
|
|
rdir: !byte 0
|
|
cheld: !byte 0 ; cursor direction repeat state
|
|
ctimer: !byte 0
|
|
cdir: !byte 0
|
|
cfheld: !byte 0 ; cursor fire edge detection state
|
|
j2bits: !byte 0
|
|
ptmp: !byte 0 ; scratch
|
|
ttx: !byte 0 ; move target (col / row)
|
|
tty: !byte 0
|
|
nch: !byte 0 ; the four slot chars around the cursor
|
|
ech: !byte 0
|
|
sch: !byte 0
|
|
wch: !byte 0
|
|
ei: !byte 0 ; enemy loop index
|
|
etries: !byte 0
|
|
etd: !byte 0
|
|
gcx: !byte 0 ; maze generator state
|
|
gcy: !byte 0
|
|
gsp: !byte 0
|
|
gn: !byte 0
|
|
gtd: !byte 0
|
|
gnx: !byte 0
|
|
gny: !byte 0
|
|
gdlist: !fill 4, 0
|
|
ex: !fill NENEMIES, 0 ; enemy positions, headings, colors
|
|
ey: !fill NENEMIES, 0
|
|
edir: !fill NENEMIES, 0
|
|
ecol: !fill NENEMIES, 0
|
|
|
|
; ---- maze generator buffers ----
|
|
visited: !fill NCELLS, 0
|
|
stackx: !fill NCELLS, 0
|
|
stacky: !fill NCELLS, 0
|