* game.asm - Maintains game state.

LANELENGTH	equ	14

INITLIVES	equ	5
INITLEVEL	equ	1
INITLANES	equ	1
INITEGGS	equ	12
INITROTS	equ	1
INITSPEED	equ	1
INITLANEY0	equ	3

MAXLIVES	equ	9
MAXLEVEL	equ	9
MAXLANES	equ	10
MAXEGGS		equ	12
MAXROTS		equ	3

nlives:	fcb	INITLIVES	; Number of lives remaining.  Initially 5.
level:	fcb	INITLEVEL	; Overall difficulty level.  Initially 1.
nlanes:	fcb	INITLANES	; Number of lanes.  Initially 1.
neggs:	fcb	INITEGGS	; Number of eggs available.  Initially 12.
nrots:	fcb	INITROTS	; Rotten eggs available.  Initially 1.
speed:	fcb	INITSPEED	; Game speed level.  Initially 1.
score:	fdb	0		; Score.  Initially 0.
laney0:	fcb	INITLANEY0	; The lane # at screen row Y0.  Initially 3.

* Chicken screen location and state.

INITCHICKX	equ	LANELENGTH/2
INITCHICKY	equ	3
INITCHICKL	equ	0
INITCHICKD	equ	0
INITCHICKH	equ	1
INITCHICKF	equ	0

chickx:	rmb	1	; On-screen X coordinate
chicky: rmb	1	; On-screen Y coordinate
chickl:	rmb	1	; Which lane is the chicky in?
chickd:	rmb	1	; Direction: right (0) or left (1)
chickh:	rmb	1	; Head state: forward (0) or back (1)
chickf:	rmb	1	; State: normal (0) or flattened (1)

* Vehicle data.

ncars:	rmb	1	; How many cars are on the board.
carx:	rmb	256
cary:	rmb	256
cartyp:	rmb	256	; Type: car (0) or truck (1)
cardir:	rmb	256	; Direction: right (0) or left (1)

* Lanes.  There may be up to 10 lanes of traffic.

* Lane #0 is where the chicken starts, the grassy area initially at the bottom of the screen.
* Lane #1 is the first lane of traffic.
* Lane #nlanes is the last lane of traffic.
* Lane #nlanes+1 is the safe area on the other side.
* Each location contains:
*    0 - nothing is here
*    1 - chicken is here
*    2 - an egg is here
*    3 - a rotten egg is here
*    4 - an explosion is here
*    n>4 - vehicle #n-5 is here

lanes:	rmb	240	; up to 12 lanes, 20 characters each
endlanes:	equ	*

* This subroutine starts a new game from scratch.

init_game:	jsr	init_LCD	; Initialize the LCD
		ldaa	#DISP_ONOFF|D_disp	; No cursor or blink
		jsr	send_cmd	; Turn cursor/blink off.	
		ldaa	#INITLIVES	; Initialize game state
		staa	nlives
		ldaa	#INITLEVEL
		staa	level
		ldaa	#INITLANES
		staa	nlanes
		ldaa	#INITEGGS
		staa	neggs
		ldaa	#INITROTS
		staa	nrots
		ldaa	#INITSPEED
		staa	speed
		ldaa	#INITLANEY0
		staa	laney0
		clr	score

* Draw lanes and grass

		ldaa	#0		; Upper-left corner
		ldab	#0
		jsr	gotoxy
		ldx	#grass_str	; Draw grass up there
		jsr	lcdstr

		ldaa	#0		; Start of 2nd row
		ldab	#1
		jsr	gotoxy
		ldx	#grass_str
		jsr	lcdstr

		ldaa	#0		; 3rd row
		ldab	#2
		jsr	gotoxy
		ldx	#lane_str	; Draw a lane there
		jsr	lcdstr

		ldaa	#0
		ldab	#3
		jsr	gotoxy
		ldx	#grass_str
		jsr	lcdstr

* Initialize scoreboard display 

		ldaa	#LANELENGTH	; Go to end of first lane
		ldab	#0
		jsr	gotoxy
		ldx	#rstr0		; Print initial row 0 string
		jsr	lcdstr
		ldaa	#LANELENGTH
		ldab	#1
		jsr	gotoxy
		ldx	#rstr1
		jsr	lcdstr
		ldaa	#LANELENGTH
		ldab	#2
		jsr	gotoxy
		ldx	#rstr2
		jsr	lcdstr
		ldaa	#LANELENGTH
		ldab	#3
		jsr	gotoxy
		ldx	#rstr3
		jsr	lcdstr

* Initialize chicken state

		ldaa	#INITCHICKX
		staa	chickx
		ldaa	#INITCHICKY
		staa	chicky
		ldaa	#INITCHICKL
		staa	chickl
		ldaa	#INITCHICKD
		staa	chickd
		ldaa	#INITCHICKH
		staa	chickh
		ldaa	#INITCHICKF
		staa	chickf

* Create chicken icon
		ldaa	#CHICKEN_CHAR
		ldy	#chikrb
		jsr	store_glyph
		ldaa	chickx		; Put the chicken on-screen
		ldab	chicky
		jsr	gotoxy
		ldaa	#CHICKEN_CHAR
		jsr	lcd_out		

* Initialize lanes
		ldx	#lanes
clrlanes:	clr	0,x
		inx
		cpx	#endlanes
		bne	clrlanes

		rts	; Return from init_game subroutine

* Main game loop subroutine.
* Controls are:
*	2 - Move chicken up
*	8 - Move chicken down
*	4 - Move chicken left
*	6 - Move chicken right
*	A - Lay an egg
*	B - Lay a rotten egg
*	* - Exit game loop (pause game and return to main menu)

debug1:	fcc	"entering main game loop"
	fcb	EOT

game_loop:
	ldx	#debug1		; Show we got here
	jsr	printmsg

* Main Loop.  Algorithm: Get an ASCII character from the keypad.  If it's a special command key,
* then do the requested command.  Otherwise, just send the character to the LCD display.  Wait
* for the key that was pressed to be released, and then repeat the whole process.

mloop:	JSR  	get_key        	; Get character from keypad into accA.

* Switch statement: Do one of several different things, depending on the value in accA.

	CMPA	#'2
	BNE	not2
	JSR	chick_moveup
	BRA	end_switch

not2:	CMPA	#'8
	BNE	not8
	JSR	chick_movedn
	BRA	end_switch

not8:	CMPA	#'4
	BNE	not4
	JSR	chick_movelf
	BRA	end_switch

not4:	CMPA	#'6
	BNE	not6
	JSR	chick_movert
	BRA	end_switch

not6:	cmpa	#'A
	bne	nota
	jsr	lay_egg
	bra	end_switch

nota:	cmpa	#'B
	bne	notb
	jsr	lay_rotten
	bra	end_switch

notb:	CMPA	#'*
	BNE	notstar
	RTS

notstar: 
end_switch: 

* Wait for the key that was pressed to be released.

wait_release:
	JSR	any_key		; Are any keys still pressed?
	BNE	wait_release	; If so, keep waiting.

	BRA	mloop		; Repeat main loop.

chick_moveup:
	ldaa	chickf
	bne	return		; If chicken is flattened, do nothing
notflat:
	ldaa	chickl		; Which lane are we in?
	deca	
	cmpa	nlanes		; If chickl=nlanes+1, can't go up
	beq	return
	ldaa	chicky		; Check chicken's y position on screen
	cmpa	#2		
	bhi	movehim
	jsr	shift_dn	; Shift display down

movehim:
	jsr	pick_chik	; pick chicken up off of road
	inc	chickl		; increment lane number
	dec	chicky		; decrement row index (y loc)
	jsr	put_chik	; put chicken back down on road

checkcoll:
return:	rts

chick_movedn:
	rts
chick_movelf:
	rts
chick_movert
	rts
lay_egg:
	rts
lay_rotten:
	rts

shift_dn:
	rts

* Pick up chicken from wherever he is
pick_chik:
	ldaa	chickx
	ldab	chicky
*	jsr	redraw_bkgrd
	rts
put_chik:
	rts

* Put the chicken down