snes: add wait_until_keypressed routine

tb1_snes/checksum.inc

@@ -1,2 +1,2 @@
-	.word	$3d2c		; Complement of checksum
-	.word	$c2d3		; Unsigned 16-bit sum of ROM
+	.word	$3851		; Complement of checksum
+	.word	$c7ae		; Unsigned 16-bit sum of ROM

tb1_snes/opening.s

@@ -168,35 +168,15 @@ opening_setup_video:
 	sta	$2105		; set Mode 3
 
 	lda	#$81		; Enable NMI (VBlank Interrupt) and joypads
-;	lda	#$01		; enable joypad
 	sta	$4200		;
 
 
 	jsr	svmw_fade_in
 
-
-
-;forever:
-;	bra	forever
-
-
-opening_joypad_read:
-	lda     $4212           ; get joypad status
-        and	#%00000001		; if joy is not ready
-        bne	opening_joypad_read	; wait
-
-        lda     $4219           ; read joypad (BYSTudlr)
-
-        and     #%11110000      ; see if a button pressed
-
-        beq     opening_joypad_read
-				; if so, skip and don't move ball
+	jsr	svmw_repeat_until_keypressed
 
 	jsr	svmw_fade_out
 
-;	lda	#$80
-;	sta	$2100		; Turn off screen
-
 	rts
 
 

tb1_snes/svmwgraph.s

@@ -235,3 +235,38 @@ done_fade_out:
 	plp			; restore status
 
 	rts			; return
+
+
+;========================
+;========================
+; repeat until keypressed
+;========================
+;========================
+; this assumes auto-joypad read enabled
+
+svmw_repeat_until_keypressed:
+	php			; save status register
+
+        sep     #$20            ; set accumulator to 8 bit
+.a8
+
+wait_for_keypress:
+	wai			; wait until next interrupt
+
+wait_for_joypad_ready:
+	lda     $4212		; get joypad status
+	and     #$01		; loop if joypad is not ready
+	bne	wait_for_joypad_ready
+
+        lda     $4219           ; read joypad (BYSTudlr)
+	bne	found_keypress
+
+	lda	$4218		; read joypad (axlriiii)
+	bne	found_keypress
+
+        bra	wait_for_keypress
+
+found_keypress:
+
+	plp			; restore status
+	rts

tb1_snes/title_screen.s

@@ -109,27 +109,15 @@ title_setup_video:
 	sta	$2100		; Turn on screen, full Brightness
 
 
-;	lda	#$81		; Enable NMI (VBlank Interrupt) and joypads
-	lda	#$01		; Enable joypad
-;	lda	#$00
+	lda	#$81		; Enable NMI (VBlank Interrupt) and joypads
 	sta	$4200		;
 
-;big:
-;	bra big
+	jsr	svmw_fade_in
 
-title_joypad_read:
-        lda     $4212           ; get joypad status
-        and     #%00000001              ; if joy is not ready
-        bne     title_joypad_read     ; wait
+	jsr	svmw_repeat_until_keypressed
 
-       lda     $4219           ; read joypad (BYSTudlr)
+	jsr	svmw_fade_out
 
-        and     #%11110000      ; see if a button pressed
-
-        beq     title_joypad_read
-
-        lda     #$80
-        sta     $2100           ; Turn off screen
 
         rts