snes: firing missiles sort of works

they wrap around top of screen so you can never fire more than 2 total.
It's a start though.

tb1_snes/checksum.inc

@@ -1,2 +1,2 @@
-	.word	$a1f3		; Complement of checksum
-	.word	$5e0c		; Unsigned 16-bit sum of ROM
+	.word	$7233		; Complement of checksum
+	.word	$8dcc		; Unsigned 16-bit sum of ROM

tb1_snes/level_1.s

@@ -31,6 +31,11 @@ joypad1_held_h	= $0d
 sprite_l	= $10
 sprite_h	= $11
 
+SPRITE_HIGH_LOOKUP = $20
+SHL2		= $21
+SHL3		= $22
+SHL4		= $23
+
 HISCORE_1	= $cb
 HISCORE_2	= $cc
 HISCORE_3	= $cd
@@ -352,6 +357,20 @@ level1_setup_video:
 
 	jsr	svmw_fade_in
 
+
+	;===========================
+	; init lookup tables
+	;===========================
+
+	lda	#$01
+	sta	SPRITE_HIGH_LOOKUP
+	lda	#$04
+	sta	SHL2
+	lda	#$10
+	sta	SHL3
+	lda	#$40
+	sta	SHL4
+
   ;====================
   ; setup the high score
   ;=====================
@@ -1775,10 +1794,22 @@ done_with_boss:
 	; Missiles are 8,9,10,11 in sprite table
 
 
-;	ldy     #$0		       		 ; point to missile[0]
+	ldy	#$8			; point to missile[0]
 move_missiles:
-;	lda     (MISSILE_PL),Y			 ; get missile[y]
-;	beq	loop_move_missiles		 ; if missile.out==0 skip
+	jsr	is_sprite_active
+	bcc	loop_move_missiles	; if not active, skip
+
+	phy
+	tya
+	asl
+	asl
+	tay
+
+	lda	$0201,Y
+	dea
+	sta	$0201,Y
+
+	ply
 
 ;	iny					 ; move to missile.y
 ;	iny
@@ -1856,50 +1887,12 @@ done_missile_collision:
 ;	jmp	loop_move_at_y
 
 loop_move_missiles:
-;	iny
-;	iny
-loop_move_at_y:
-;	iny
-;	cpy	#NUM_MISSILES*3	       ; have we checked all missiles?
-;	bne	move_missiles	       ; if not, loop
+	iny
+	cpy	#(8+NUM_MISSILES)	; have we checked all missiles?
+	bne	move_missiles		; if not, loop
 
 done_move_missiles:
 
-;	ldy	#$0		       ; point to missiles[0]
-draw_missiles:
-;	lda     (MISSILE_PL),Y	       ; get missile[y]
-;	beq	loop_draw_missiles     ; if missile.out==0 skip
-
-;	iny			       ; point to missile.x
-;	lda	(MISSILE_PL),Y	       ; load it
-;	sta	CH
-;	iny	  		       ; point to missile.y
-;	lda	(MISSILE_PL),Y	       ; load it
-;	sta	CV
-
-;	sty	YSAV1		       ; save Y
-
-;	lda	#>missile_sprite       ; point to the missile sprite
-;	sta	STRINGH
-;	lda	#<missile_sprite
-;	sta	STRINGL
-;	jsr	blit   		       ; blit the missile sprite
-
-;	ldy	YSAV1		       ; restore Y
-
-;	jmp	loop_draw_missiles_noadd
-
-loop_draw_missiles:
-;	iny
-;	iny
-
-loop_draw_missiles_noadd:
-;	iny
-
-;	cpy	#NUM_MISSILES*3	       ; have we looped through them all?
-;	bne	draw_missiles	       ; if not, loop
-
-
 	;===============================
 	; handle joypad input
 	;===============================
@@ -1946,35 +1939,37 @@ key_A:
 	bit	#$80
 	beq	game_unknown
 
-;	ldy	#$0	    	       ; point to missile[y]
+	ldy	#$8			; point to missile[y]
 fire_missiles:
-;	lda     (MISSILE_PL),Y	       ; get missile[y].out
-;	bne	end_fire_loop	       ; if not out, skip ahead
+	jsr	is_sprite_active
+	bcs	end_fire_loop		; if active, skip to next
+
+	phy
+	tya
+	asl
+	asl
+	tay
 
-;	lda	#$1		       ; set missile[y].out=1
-;	sta	(MISSILE_PL),Y
-;	iny		      	       ; point to missile[y].x
 	lda	#8
 	clc
-	adc	shipx		       ; missile[y].x=shipx+8
-	sta	$0220
-;	iny		      	       ; point to missile[y].y
-	lda	#190		       ; set to 190
-	sta	$0221
+	adc	shipx			; missile[y].x=shipx+8
+	sta	$0200,Y			; $220 + 4*(Y-8)
 
-	lda	$0402
-	and	#.LOBYTE(~$1)
-	sta	$0402
+	lda	#190			; set to 190
+	sta	$0201,Y
 
-;	jmp	done_fire_missiles
 
-;end_fire_loop:
-;	iny
-;	iny
-;	iny
+	ply
+	jsr	activate_sprite
+
+	bra	done_fire_missiles	; done firing missile
+
+end_fire_loop:
+	iny				; point to next missile
+
+	cpy	#(8+NUM_MISSILES)	; see if we have more missiles
+	bne	fire_missiles		; if so, loop
 
-;	cpy	#NUM_MISSILES*3	       ; see if we have more missiles
-;	bne	fire_missiles	       ; if so, loop
 done_fire_missiles:
 
 	jmp	move_ship
@@ -2448,7 +2443,7 @@ update_shields:
 
 	lda	SHIELDS
 	bne	normal_shields
-	
+
 
 flash_shields:
 	lda	#$7f
@@ -2457,29 +2452,29 @@ flash_shields:
 	iny
 	cpy	#$7
 	bne	flash_shields
-	jmp	shields_line	
+	jmp	shields_line
 
-normal_shields:	
+normal_shields:
 	lda	#$80
 	ora	(STRINGL),Y
 	sta	(STRINGL),Y
 	iny
 	cpy	#$7
 	bne	normal_shields
-	
+
 shields_line:
 
 	ldy  	#$A
 	ldx	#$0
-shield_line_loop:	
-	
+shield_line_loop:
+
 	cpx	SHIELDS
 	bmi	shield_box
 	lda	#'_'+128
 	jmp	shield_char
 shield_box:
 	lda	#' '
-shield_char:	
+shield_char:
 	sta	(STRINGL),Y
 	iny
 	iny

tb1_snes/svmwgraph.s

@@ -271,3 +271,90 @@ found_keypress:
 
 	plp			; restore status
 	rts
+
+;===========================
+;===========================
+; is_sprite_active
+;===========================
+;===========================
+; assumes high sprite table at $0400
+; sets carry if active
+; clears carry if not
+; sprite number in X
+is_sprite_active:
+
+;	php
+	phx
+	phy
+
+	lda	#$0
+	xba
+
+	tyx
+
+	; address=$0400 + Y/4
+	txa
+	lsr
+	lsr
+	tay
+
+	txa
+	and	#$3
+	tax
+	lda	SPRITE_HIGH_LOOKUP,X
+
+	and	$0400,Y			; sprite on screen when bit is 0
+	beq	sprite_is_active
+
+	clc
+	bra	done_sprite_is_active
+
+sprite_is_active:
+	sec
+
+done_sprite_is_active:
+	ply
+	plx
+;	plp
+	rts
+
+
+;===========================
+;===========================
+; activate_sprite
+;===========================
+;===========================
+; assumes high sprite table at $0400
+; sets carry if active
+; clears carry if not
+; sprite number in X
+activate_sprite:
+
+	php
+	phx
+	phy
+
+	lda	#$0
+	xba
+
+	tyx
+
+	; address=$0400 + Y/4
+	txa
+	lsr
+	lsr
+	tay
+
+	txa
+	and	#$3
+	tax
+	lda	SPRITE_HIGH_LOOKUP,X
+	eor	#$ff
+
+	and	$0400,Y			; sprite on screen when bit is 0
+	sta	$0400,Y
+
+	ply
+	plx
+	plp
+	rts