megademo: c64 cursor

megademo/Makefile

@@ -21,7 +21,7 @@ MEGADEMO:	megademo.o
 
 megademo.o:	megademo.s \
 	zp.inc hardware.inc \
-	gr_hline.s gr_offsets.s vapor_lock.s delay_a.s \
+	gr_hline.s gr_offsets.s vapor_lock.s delay_a.s wait_keypress.s \
 	c64_opener.s c64.img.lz4 \
 	falling_apple.s apple_40_96.inc
 	ca65 -o megademo.o megademo.s -l megademo.lst

megademo/c64_opener.s

@@ -4,7 +4,16 @@
 ; Apple II has a lot of trouble making clear text with bluish background
 ; would be a lot clearer if I used black and white
 
+TOP = $F0
+BOTTOM = $F1
+
 c64_opener:
+	;===================
+	; init vars
+	;===================
+	lda	#0
+	sta	TOP
+	sta	BOTTOM
 
 	;===================
 	; set graphics mode
@@ -34,7 +43,156 @@ c64_opener:
 	jsr	lz4_decode
 
 
-	rts
+	jsr	wait_until_keypress
+
+
+	;==============================
+	; setup graphics for vapor lock
+	;==============================
+
+	jsr	vapor_lock						; 6
+
+	bit	PAGE0                   ; first graphics page		; 4
+	bit	FULLGR			; full screen graphics		; 4
+	bit	HIRES			; hires mode !!!		; 4
+	bit	SET_GR			; graphics mode			; 4
+
+	; vapor lock returns with us at beginning of hsync in line
+	; 114 (7410 cycles), so with 5070 + 4550 lines to go (9620)
+	; - 16 = 9604
+
+	; Try X=57 Y=33 cycles=9604
+
+	ldy	#33							; 2
+loopcoA:ldx	#57							; 2
+loopcoB:dex								; 2
+	bne	loopcoB							; 2nt/3
+	dey								; 2
+	bne	loopcoA							; 2nt/3
+
+        jmp     c64_split
+.align  $100
+
+
+	;================================================
+	; c64_split
+	;================================================
+	; We want to:
+	;	Wait 3s, just flashing cursor@1Hz
+	;	Then slowly open to text page0
+	; Count to 480?
+	; Width = 0 - 40, 10 steps
+
+c64_split:
+
+	; kill 65*192 = 12480
+
+	; Try X=24 Y=99 cycles=12475 R5
+
+	nop
+	lda	$0
+
+	ldy     #99							; 2
+loopcoC:ldx	#24							; 2
+loopcoD:dex								; 2
+	bne	loopcoD							; 2nt/3
+	dey								; 2
+	bne	loopcoC							; 2nt/3
+
+
+
+	;======================================================
+	; We have 4550 cycles in the vblank, use them wisely
+	;======================================================
+	; do_nothing should be      4550
+	;			     -10 keyboard handling
+	;			 =  4540
+
+	clc								; 2
+	lda	BOTTOM							; 3
+	adc	#1							; 2
+	sta	BOTTOM							; 3
+	cmp	#30							; 2
+	bne	not_thirty						; 3/2
+thirty:
+	lda	#0							; 2
+	sta	BOTTOM							; 3
+	lda	TOP							; 3
+	clc								; 2
+	adc	#1							; 2
+	sta	TOP							; 3
+not_thirty:
+
+
+
+	; handle the cursor
+	; FIXME: not aligned well.  Do we care?
+
+	lda	TOP							; 3
+	and	#$1							; 2
+	beq	cursor_off						; 3/2
+cursor_on:
+	; it's lSB first
+	; blue is 6
+	; 1 1111110
+	lda	#$fE	; blue						; 2
+	sta	$3300	; 52						; 4
+	sta	$3B00	; 54						; 4
+	sta	$2380	; 56						; 4
+	sta	$2B80	; 58						; 4
+	; purple is 2
+	; 0 1111110
+	lda	#$7E	; purple					; 2
+	sta	$3700	; 53						; 4
+	sta	$3F00	; 55						; 4
+	sta	$2780	; 57						; 4
+	sta	$2F80	; 59						; 4
+
+	jmp	cursor_done						; 3
+cursor_off:
+	; blue is 6
+	; 1 1010101
+	lda	#$d5	; blue						; 2
+	sta	$3300	; 52						; 4
+	sta	$3B00	; 54						; 4
+	sta	$2380	; 56						; 4
+	sta	$2B80	; 58						; 4
+	; purple is 2
+	; 0 1010101
+	lda	#$55	; purple					; 2
+	sta	$3700	; 53						; 4
+	sta	$3F00	; 55						; 4
+	sta	$2780	; 57						; 4
+	sta	$2F80	; 59						; 4
+
+
+
+cursor_done:
+
+
+
+	; Try X=9 Y=89 cycles=4540
+
+	nop
+	lda	$0
+
+	ldy     #89							; 2
+loopcoE:ldx	#9							; 2
+loopcoF:dex								; 2
+	bne	loopcoF							; 2nt/3
+	dey								; 2
+	bne	loopcoE							; 2nt/3
+
+
+	lda	KEYPRESS				; 4
+	bpl	no_c64_keypress				; 3
+	jmp	done_c64
+no_c64_keypress:
+
+	jmp	c64_split				; 3
+
+done_c64:
+	rts						; 6
 
 	;===================
 	; graphics

megademo/megademo.s

@@ -14,7 +14,7 @@
 
 	; C64 Opening Sequence
 
-;	jsr	c64_opener
+	jsr	c64_opener
 
 	; Falling Apple II
 
@@ -39,3 +39,4 @@ loop_forever:
 	.include	"gr_hline.s"
 	.include	"vapor_lock.s"
 	.include	"delay_a.s"
+	.include	"wait_keypress.s"

megademo/wait_keypress.s

@@ -0,0 +1,5 @@
+wait_until_keypress:
+	lda	KEYPRESS				; 4
+	bpl	wait_until_keypress			; 3
+	bit	KEYRESET	; clear the keyboard buffer
+	rts						; 6