#msg thought creates

#def scan_w

	out	p_throttle	100
	set	ax		1
	int     i_keepshift             ; maintain turret facing

;---------------------------------------------------------------------

!start
	call	!do_scan

!turn_random
	in 	p_random      	ax      ; Get random number 
        and     ax      	0xFF    ; now it is 0-255.
!go
	call 	!turn
	jmp 	!start

;---------------------------------------------------------------------


!check_boundary
	int	i_locate		;puts x,y in ex, fx

	cmp	ex		900	;are we near the right side?
	ja	!turnl			;if so, turn left
	cmp	ex		100	;are we near the left side
	jb	!turnr			;if so, turn right
	cmp	fx		900	;are we near the bottom
	ja	!turnu			;if so, turn up
	cmp	fx		100	; are we near the top
	jb	!turnd			;if so, tun down
	ret
!turnl
        in     	p_random    	ax      ; random number
        and     ax      	0x40    ; now it is 0-63.
        add     ax      	0xA0    ; now it is 160-223
        call    !turn            	; turn to that heading.
        ret	
!turnr
        in     	p_random    	ax      ; random number
        and     ax      	0x40    ; now it is 0-63.
        add     ax      	0x20    ; now it is 32-95
        call    !turn            	; turn to that heading.
        ret	
!turnu
        in     	p_random    	ax      ; random number
        and     ax      	0x40    ; now it is 0-63.
        add     ax     		0E0h    ; now it is 224-287.
        and     ax     		255     ; now it is 224-255 or 0-31.
        call    !turn            	; turn to that heading.
        ret	
!turnd
        in     	p_random    	ax      ; random number
        and     ax      	0x40    ; now it is 0-63.
        add     ax      	0x60    ; now it is 96-159
        call    !turn            	; turn to that heading.
        ret	

;---------------------------------------------------------------------
;set course to heading thats in AX.
!turn
        mov     bx     		@1      ; get current desired heading                                ; (not actual heading)
        sub     ax     		bx      ; get number of degrees to turn.
        out     p_steering 	ax      ; turn!
!not_turned
        in      p_compass     	bx      ; bx = heading
        cmp     bx   		@1      ; is heading equal to desired heading?
        jne     !not_turned             ; if not, wait until it is.
        out     p_throttle	100     ; Throttle to 100%
	ret

;---------------------------------------------------------------------
;scan for targets...

!do_scan
	out	p_scanarc	scan_w	; change scan arc 
	in	p_scan		ax	; do the scan
	call	!check_boundary
	cmp	ax		1500	; did we find a target?
	jb	!shrink_arc		; if so, shrink arc so we can pinpoint target
	set	scan_w		64	; see none? keep arc at widest till we do
	out	p_trotate	0x80	; flip turret = scan angle
	ret

;---------------------------------------------------------------------
; shrinks the scan arc by 1/2
!shrink_arc
	out	p_throttle	25
	cmp	@3		1	
	je	!one
	ja	!two
	cmp	@3		-1
	je	!negone
	jb	!negtwo
	shr	scan_w		2
	call	!shoot
	ret
!one
	shr	scan_w		1	; adjust arc
	out	p_trotate	scan_w	; rotate turret
	shr	scan_w		1
	ret
!two
	out	p_trotate	scan_w	; rotate turret
	shr	scan_w		2	; adjust arc
	ret
!negone
	shr	scan_w		1	; adjust arc
	neg	scan_w
	out	p_trotate	scan_w	; rotate turret
	neg	scan_w
	shr	scan_w		1
	ret
!negtwo
	neg	scan_w
	out	p_trotate	scan_w	; rotate turret
	neg	scan_w
	shr	scan_w		-2	; adjust arc
	ret
;---------------------------------------------------------------------

!shoot
	cmp	scan_w		2
	ja	!endshoot
	in	p_damage	ax
	cmp	ax		25
	ja	!sh	
	int	i_overburn	
!sh
	out	p_fire		
	out	p_fire		
	in	p_heat		bx
	cmp	bx		300
	jae	!speedup
	out	p_fire		
	out     p_fire		
!speedup
	set	scan_w		8
	out	p_throttle	100
!endshoot
	ret

;---------------------------------------------------------------------
#end