mode7_demo: fade in / fade out

could stand to be optimized

mode7_demo/mode7_demo.s

@@ -23,7 +23,29 @@
 
 	jsr	load_rle_gr
 
-loop_forever:
+demo_loop:
+
+	jsr	fade_in
+
+	lda	#255
+	jsr	WAIT
+
+	jsr	fade_out
+
+
+	jmp	demo_loop
+
+
+
+
+
+
+
+	;============================================
+	; gr, "fade" out.  Badly fake a pallette fade
+	;============================================
+	; Image to fade out should be in $C00
+fade_out:
 
 	lda	#<fade_lookup
 	sta	GBASL
@@ -69,48 +91,98 @@ loop_forever:
 	lda	#200
 	jsr	WAIT
 
+	rts
 
+	;===========================================
+	; gr, "fade" in.  Badly fake a pallette fade
+	;===========================================
+	; Image to fade in should be in $C00
+fade_in:
 
-	jmp	loop_forever
+	lda	#<(fade_lookup+48)
+	sta	GBASL
+	lda	#>(fade_lookup+48)
+	sta	GBASH
 
+	jsr	gr_fade
+	jsr	page_flip
 
-;================================================
-; Fade in/out lowres graphics
-; GR image should be in $C00
+	lda	#200
+	jsr	WAIT
+
+	lda	#<(fade_lookup+32)
+	sta	GBASL
+	lda	#>(fade_lookup+32)
+	sta	GBASH
+
+	jsr	gr_fade
+	jsr	page_flip
+
+	lda	#200
+	jsr	WAIT
+
+	lda	#<(fade_lookup+16)
+	sta	GBASL
+	lda	#>(fade_lookup+16)
+	sta	GBASH
+
+	jsr	gr_fade
+	jsr	page_flip
+
+	lda	#200
+	jsr	WAIT
+
+	lda	#<(fade_lookup+0)
+	sta	GBASL
+	lda	#>(fade_lookup+0)
+	sta	GBASH
+
+	jsr	gr_fade
+	jsr	page_flip
+
+	lda	#200
+	jsr	WAIT
+
+	rts
+
+	;================================================
+	; Fade in/out lowres graphics
+	; GR image should be in $C00
+	; pointer to fade table in GBASL/GBASH
 
 gr_fade:
 
 	ldx	 #0		; set ypos to zero			; 2
 
-gr_copy_loop:
+gr_fade_loop:
 	lda	gr_offsets,X	; lookup low byte for line addr		; 4+
 
-	sta	gr_copy_line1+1	; out and in are the same		; 4
-	sta	gr_copy_line2+1						; 4
+	sta	gr_fade_line1+1	; out and in are the same		; 4
+	sta	gr_fade_line2+1						; 4
 
 	lda	gr_offsets+1,X	; lookup high byte for line addr	; 4+
 	clc								; 2
 	adc	DRAW_PAGE						; 3
-	sta	gr_copy_line2+2						; 4
+	sta	gr_fade_line2+2						; 4
 
 	lda	gr_offsets+1,X	; lookup high byte for line addr	; 4+
 	adc	#$8		; for now, fixed 0xc			; 2
-	sta	gr_copy_line1+2						; 4
+	sta	gr_fade_line1+2						; 4
 
 	ldy     #0		; set xpos counter to 0			; 2
 
 
 	cpx	#$8		; don't want to copy bottom 4*40	; 2
-	bcs	gr_copy_above4						; 2nt/3
+	bcs	gr_fade_above4						; 2nt/3
 
-gr_copy_below4:
+gr_fade_below4:
 	ldy	#119		; for early ones, copy 120 bytes	; 2
-	bcc	gr_copy_line1	;					; 3
+	bcc	gr_fade_line1	;					; 3
 
-gr_copy_above4:			; for last four, just copy 80 bytes
+gr_fade_above4:			; for last four, just copy 80 bytes
 	ldy	#79							; 2
 
-gr_copy_line1:
+gr_fade_line1:
 	lda	$ffff,Y		; load a byte (self modified)		; 4+
 	pha
 
@@ -139,16 +211,16 @@ gr_copy_line1:
 
 	ldy	TEMPY		; restore Y
 
-gr_copy_line2:
+gr_fade_line2:
 	sta	$ffff,Y		; store a byte (self modified)		; 5
 	dey			; decrement pointer			; 2
-	bpl	gr_copy_line1	;					; 2nt/3
+	bpl	gr_fade_line1	;					; 2nt/3
 
-gr_copy_line_done:
+gr_fade_line_done:
 	inx			; increment ypos value			; 2
 	inx			; twice, as address is 2 bytes		; 2
 	cpx	#16		; there are 8*2 of them			; 2
-	bne	gr_copy_loop	; if not, loop				; 3
+	bne	gr_fade_loop	; if not, loop				; 3
 	rts								; 6