From f03e4523266c9a8966fb22044cb8ef46c15941e5 Mon Sep 17 00:00:00 2001
From: Vince Weaver <vince@deater.net>
Date: Wed, 8 Dec 2021 17:01:22 -0500
Subject: [PATCH] hgr: rectangle, more optimization

---
 graphics/hgr/transitions/rectangle.s | 134 ++++++++++++++++-----------
 1 file changed, 79 insertions(+), 55 deletions(-)

diff --git a/graphics/hgr/transitions/rectangle.s b/graphics/hgr/transitions/rectangle.s
index 5186c25f..c8ea4469 100644
--- a/graphics/hgr/transitions/rectangle.s
+++ b/graphics/hgr/transitions/rectangle.s
@@ -1,6 +1,17 @@
 ; Rectangle Transition
 ;   "night fell like a power point"
 
+; 167 bytes -- original
+; 166 bytes -- make end loop beq not jmp
+; 156 bytes -- use GBASL/GBASH rather than self-modifying code
+; 154 bytes -- countdown X in inner loop
+; 153 bytes -- remove unnecessary clc
+; 151 bytes -- was setting Y twice
+; 147 bytes -- lookup table for XADD/YADD
+; 145 bytes -- stop on YY value
+; 150 bytes -- have it cycle colors
+; 147 bytes -- init zp to 0 in loop
+; 144 bytes -- put lookup table in zero page
 
 ; zero page
 GBASL	= $26
@@ -12,6 +23,14 @@ HGR_Y           = $E2
 HGR_COLOR       = $E4
 HGR_PAGE        = $E6
 
+GBASH_SAVED = $F5
+
+TABLE	= $F0	; should be 0
+TABLE2  = $F1	; should be 1
+TABLE3	= $F2	; should be 0
+TABLE4  = $F3	; should be -1
+TABLE5	= $F4	; should be 0
+
 XX	= $F6
 YY	= $F7
 XADD	= $F8
@@ -42,11 +61,19 @@ rectangle:
 	jsr	HGR2		; set hi-res 140x192, page2, fullscreen
 				; A and Y both 0 at end
 
-	sty	XX		; X = 0
-	sty	YY		; Y = 0
-	sty	YMIN		; ymin=0
-	dey
-	sty	XMIN		; xmin = -1
+over:
+	; clear our zp things to 0
+
+	ldx	#15
+clear_loop:
+	sta	$EF,X
+	dex
+	bne	clear_loop
+
+	dec	XMIN		; xmin = -1
+
+	inc	TABLE2
+	dec	TABLE4
 
 	ldy	#39
 	sty	XMAX		; xmax=39
@@ -58,90 +85,82 @@ main_loop:
 	; left to right horizontal
 
 	dec	YMAX
-	ldy	#$1
-	sty	XADD
-	dey
-	sty	YADD
-
+	; XADD=1,YADD=0
 	jsr	draw_line
 
-	inc	XMIN
-
 	; top to bottom vertical
-	ldy	#0
-	sty	XADD
-	iny
-	sty	YADD
+	inc	XMIN
+	; XADD=0,YADD=1
 	jsr	draw_line
 
 	; right to left horizontal
-	ldy	#$ff
-	sty	XADD
-	iny
-	sty	YADD
+	inc	YMIN
+	; XADD=-1,YADD=0
 	jsr	draw_line
 
 	; bottom to top vertical
 	dec	XMAX
-;	inc	XMIN
-	inc	YMIN
-
-	ldy	#$ff
-	sty	YADD
-	iny
-	sty	XADD
+	; XADD=0,YADD=-1
 	jsr	draw_line
 
-;	inc	XX
+	; YY is in A here
+	; X is zero here
 
-	lda	XX
 	cmp	#12
 	bne	main_loop
 
-
-
 end:
-	jmp	end
+	txa			; put zero into A
+	inc	color_smc+1
+	bne	over
 
 
-; horizontal
+	;=================================
+	; draw a horizontal/vertical line
+	;	8 rows high
 draw_line:
 
-	lda	YY
+get_next:
+	lda	FRAME
+	and	#$3
+	tax
+	lda	TABLE2,X
+	sta	XADD
+	lda	TABLE,X
+	sta	YADD
+	inc	FRAME
+
+repeat_line:
+	lda	YY		; YY * 8
 	asl
 	asl
 	asl
 
 	jsr	HPOSN		; (Y,X),(A)  (values stores in HGRX,XH,Y)
-	lda	GBASL
-	sta	output_smc+1
 	lda	GBASH
-	sta	output_smc+2
-
-	; first top right
-horiz_smc1:
-	ldx	XX
+	sta	GBASH_SAVED	; reset top of box
 
 out_loop:
-	ldy	#0
-	lda	GBASH
-	sta	output_smc+2
+	ldx	#8
+	lda	GBASH_SAVED
+	sta	GBASH
+	ldy	XX
 in_loop:
-	lda	#$FF
-	ldx	XX
-output_smc:
-	sta	$4000,X
 
-	lda	output_smc+2
+color_smc:
+	lda	#$7F		; draw white box
+output_smc:
+	sta	(GBASL),Y
+
+	lda	GBASH		; move to next line
 	clc
 	adc	#$4
-	sta	output_smc+2
+	sta	GBASH
 
-	iny
-	cpy	#8
+	dex
 	bne	in_loop
 
-	lda	#25
+	lda	#25		; wait a bit
 	jsr	WAIT
 
 check_x:
@@ -158,7 +177,7 @@ check_x:
 	bne	out_loop
 
 check_y:
-	clc
+	; c should already be clear
 	lda	YY
 	adc	YADD
 	sta	YY
@@ -168,7 +187,12 @@ check_y:
 	cmp	YMAX
 	beq	done_line
 
-	bne	draw_line
+	bne	repeat_line
 
 done_line:
 	rts
+
+
+
+
+