From 889515f2c5d93f8901a636a48e7da3e864798cf5 Mon Sep 17 00:00:00 2001
From: Vince Weaver <vince@deater.net>
Date: Wed, 30 Jan 2013 01:29:14 -0500
Subject: [PATCH] snes: missiles die when off end of screen

---
 tb1_snes/checksum.inc |  4 ++--
 tb1_snes/level_1.s    | 24 +++++++++---------------
 tb1_snes/svmwgraph.s  | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 17 deletions(-)

diff --git a/tb1_snes/checksum.inc b/tb1_snes/checksum.inc
index b18eab8..852afff 100644
--- a/tb1_snes/checksum.inc
+++ b/tb1_snes/checksum.inc
@@ -1,2 +1,2 @@
-	.word	$7233		; Complement of checksum
-	.word	$8dcc		; Unsigned 16-bit sum of ROM
+	.word	$60fc		; Complement of checksum
+	.word	$9f03		; Unsigned 16-bit sum of ROM
diff --git a/tb1_snes/level_1.s b/tb1_snes/level_1.s
index dcbb117..4ceeafb 100644
--- a/tb1_snes/level_1.s
+++ b/tb1_snes/level_1.s
@@ -1811,24 +1811,18 @@ move_missiles:
 
 	ply
 
-;	iny					 ; move to missile.y
-;	iny
-;	clc					 ; clear carry
-;	lda	(MISSILE_PL),Y			 ; get missile.y
-;	adc	#$FF				 ; move up (subtract 1)
-;	sta	(MISSILE_PL),Y			 ; store missile.y
-;	bpl	missile_collision_detection	 ; if not off screen, contine
+	cmp	#200
 
-;	dey					 ; back up to missile.out
-;	dey
-;	lda	#$0
-;	sta	(MISSILE_PL),Y			 ; set missile.out=0
+	; bge
+	bcc	missile_collision_detection	; if not off screen, contine
 
-;	lda	#<(~PERFECT_AIM)		 ; shot missed!
-;	and	BONUS_FLAGS     		 ; clear perfect shot flag
-;	sta	BONUS_FLAGS
+	jsr	deactivate_sprite
 
-;	jmp	loop_move_missiles		 ; continue
+	lda	#<(~PERFECT_AIM)		; shot missed!
+	and	BONUS_FLAGS			; clear perfect shot flag
+	sta	BONUS_FLAGS
+
+	jmp	loop_move_missiles		; continue
 
 missile_collision_detection:
 
diff --git a/tb1_snes/svmwgraph.s b/tb1_snes/svmwgraph.s
index 83d2b0b..0523cdc 100644
--- a/tb1_snes/svmwgraph.s
+++ b/tb1_snes/svmwgraph.s
@@ -358,3 +358,43 @@ activate_sprite:
 	plx
 	plp
 	rts
+
+
+;===========================
+;===========================
+; deactivate_sprite
+;===========================
+;===========================
+; assumes high sprite table at $0400
+; sets carry if active
+; clears carry if not
+; sprite number in X
+deactivate_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
+
+	ora	$0400,Y			; sprite off screen when bit is 1
+	sta	$0400,Y
+
+	ply
+	plx
+	plp
+	rts