dos33fsprogs/mist/keyboard.s

	;==============================
	; Handle Keypress
	;==============================
handle_keypress:

	lda	KEYPRESS
	bmi	keypress

	jmp	no_keypress

keypress:
	and	#$7f			; clear high bit
	and	#$df			; convert uppercase to lower case

check_sound:
	cmp	#$14			; control-T
	bne	check_joystick

	lda	SOUND_STATUS
	eor	#SOUND_DISABLED
	sta	SOUND_STATUS
	jmp	done_keypress

	; can't be ^J as that's the same as down
check_joystick:
	cmp	#$10			; control-P
	bne	check_load

	lda	JOYSTICK_ENABLED
	eor	#1
	sta	JOYSTICK_ENABLED
	jmp	done_keypress

check_load:
	cmp	#$C			; control-L
	bne	check_save

	jsr	load_game
	jmp	done_keypress

check_save:
	cmp	#$13			; control-S
	bne	check_left

	jsr	save_game
	jmp	done_keypress

check_left:
	cmp	#'A'
	beq	left_pressed
	cmp	#8			; left key
	bne	check_right
left_pressed:
	dec	CURSOR_X
	jmp	done_keypress

check_right:
	cmp	#'D'
	beq	right_pressed
	cmp	#$15			; right key
	bne	check_up
right_pressed:
	inc	CURSOR_X
	jmp	done_keypress

check_up:
	cmp	#'W'
	beq	up_pressed
	cmp	#$0B			; up key
	bne	check_down
up_pressed:
	dec	CURSOR_Y
	dec	CURSOR_Y
	jmp	done_keypress

check_down:
	cmp	#'S'
	beq	down_pressed
	cmp	#$0A
	bne	check_return
down_pressed:
	inc	CURSOR_Y
	inc	CURSOR_Y
	jmp	done_keypress

check_return:
	cmp	#' '
	beq	return_pressed
	cmp	#13
	bne	done_keypress

return_pressed:

	lda	IN_SPECIAL
	beq	not_special_return

special_return:
	jsr	handle_special

	; special case, don't make cursor visible
	jmp	no_keypress

not_special_return:

	lda	IN_RIGHT
	beq	not_right_return

	cmp	#1
	beq	right_return

right_uturn:
	jsr	uturn
	jmp	no_keypress

right_return:
	jsr	turn_right
	jmp	no_keypress

not_right_return:

	lda	IN_LEFT
	beq	not_left_return

	cmp	#1
	beq	left_return
left_uturn:
	jsr	uturn
	jmp	no_keypress

left_return:
	jsr	turn_left
	jmp	no_keypress

not_left_return:

	jsr	go_forward
	jmp	no_keypress

done_keypress:
	lda	#1			; make cursor visible
	sta	CURSOR_VISIBLE

no_keypress:
	bit	KEYRESET
	rts

	;============================
	; handle_special
	;===========================

	; set up jump table fakery
handle_special:
	ldy	#LOCATION_SPECIAL_FUNC+1
	lda	(LOCATION_STRUCT_L),Y
	pha
	dey
	lda	(LOCATION_STRUCT_L),Y
	pha
	rts


	;=============================
	; change direction
	;=============================
change_direction:

	; load background
	lda	DIRECTION
	bpl	no_split

	; split text/graphics
	bit	TEXTGR

	; also change sprite cutoff
	ldx	#40
	stx	psc_smc1+1
	stx	psc_smc2+1

	jmp	done_split
no_split:
	bit	FULLGR

	; also change sprite cutoff
	ldx	#48
	stx	psc_smc1+1
	stx	psc_smc2+1

done_split:
	and	#$f			; mask off special flags
	tay
	lda	log2_table,Y
	asl
	clc
	adc	#LOCATION_NORTH_BG
	tay

	lda	(LOCATION_STRUCT_L),Y
	sta	LZSA_SRC_LO
	iny
	lda	(LOCATION_STRUCT_L),Y
	sta	LZSA_SRC_HI
	lda	#$c			; load to page $c00
	jsr	decompress_lzsa2_fast

	rts


	;=============================
	; change location
	;=============================
change_location:
	; reset graphics
	bit	SET_GR

	; reset pointer to not visible, centered
	lda	#0
	sta	ANIMATE_FRAME
	sta	CURSOR_VISIBLE
	lda	#20
	sta	CURSOR_X
	sta	CURSOR_Y

	lda	LOCATION
	asl
	tay

	lda	(LOCATIONS_L),Y
	sta	LOCATION_STRUCT_L
	iny
	lda	(LOCATIONS_L),Y
	sta	LOCATION_STRUCT_H

	jsr	change_direction

	rts

	;==========================
	; go forward
	;===========================
go_forward:

	; update new location

	lda	DIRECTION
	and	#$f
	tay
	lda	log2_table,Y
	clc
	adc	#LOCATION_NORTH_EXIT
	tay
	lda	(LOCATION_STRUCT_L),Y

	cmp	#$ff
	beq	cant_go_forward

	sta	LOCATION

	; update new direction

	lda	DIRECTION
	and	#$f
	tay
	lda	log2_table,Y
	clc
	adc	#LOCATION_NORTH_EXIT_DIR
	tay
	lda	(LOCATION_STRUCT_L),Y
	sta	DIRECTION

	jsr	change_location
cant_go_forward:
	rts

	;==========================
	; turn left
	;===========================
turn_left:

	lda	DIRECTION
	and	#$f
	cmp	#DIRECTION_N
	beq	go_west
	cmp	#DIRECTION_W
	beq	go_south
	cmp	#DIRECTION_S
	beq	go_east
	bne	go_north

	;==========================
	; turn right
	;===========================
turn_right:
	lda	DIRECTION
	and	#$f
	cmp	#DIRECTION_N
	beq	go_east
	cmp	#DIRECTION_E
	beq	go_south
	cmp	#DIRECTION_S
	beq	go_west
	bne	go_north

	;==========================
	; uturn
	;===========================
uturn:

	lda	DIRECTION
	and	#$f
	cmp	#DIRECTION_N
	beq	go_south
	cmp	#DIRECTION_W
	beq	go_east
	cmp	#DIRECTION_S
	beq	go_north
	bne	go_west

go_north:
	lda	#DIRECTION_N
	jmp	done_turning
go_east:
	lda	#DIRECTION_E
	jmp	done_turning
go_south:
	lda	#DIRECTION_S
	jmp	done_turning
go_west:
	lda	#DIRECTION_W
	jmp	done_turning


done_turning:
	sta	DIRECTION
	jsr	change_direction

	rts