From 19b2aac527651e2943107988871d75318654f626 Mon Sep 17 00:00:00 2001
From: Vince Weaver <vince@deater.net>
Date: Wed, 24 Nov 2021 00:00:53 -0500
Subject: [PATCH] hgr: circle

---
 graphics/hgr/plasma/Makefile |  14 +++-
 graphics/hgr/plasma/circle.s | 129 +++++++++++++++++++++++++++++++++++
 2 files changed, 141 insertions(+), 2 deletions(-)
 create mode 100644 graphics/hgr/plasma/circle.s

diff --git a/graphics/hgr/plasma/Makefile b/graphics/hgr/plasma/Makefile
index 3d1bae09..257cc9eb 100644
--- a/graphics/hgr/plasma/Makefile
+++ b/graphics/hgr/plasma/Makefile
@@ -8,11 +8,12 @@ EMPTYDISK = ../../../empty_disk/empty.dsk
 all:	plasma_hgr.dsk
 
 plasma_hgr.dsk:	HELLO OVAL PURPLE_WAVES ZEBRA JAWS TWIST OVAL_FLIP MOVING \
-		MIRROR THICK_SINE THICK_LINES
+		MIRROR THICK_SINE THICK_LINES CIRCLE
 	cp $(EMPTYDISK) plasma_hgr.dsk
 	$(DOS33) -y plasma_hgr.dsk SAVE A HELLO
 	$(DOS33) -y plasma_hgr.dsk BSAVE -a 0x3F5 THICK_SINE
 	$(DOS33) -y plasma_hgr.dsk BSAVE -a 0x3F5 THICK_LINES
+	$(DOS33) -y plasma_hgr.dsk BSAVE -a 0x3F5 CIRCLE
 	$(DOS33) -y plasma_hgr.dsk BSAVE -a 0xc00 OVAL
 	$(DOS33) -y plasma_hgr.dsk BSAVE -a 0xc00 PURPLE_WAVES
 	$(DOS33) -y plasma_hgr.dsk BSAVE -a 0xc00 ZEBRA
@@ -53,6 +54,15 @@ thick_sine.o:	thick_sine.s
 
 ###
 
+CIRCLE:	circle.o
+	ld65 -o CIRCLE circle.o -C $(LINKERSCRIPTS)/apple2_3f5.inc
+
+circle.o:	circle.s
+	ca65 -o circle.o circle.s -l circle.lst
+
+
+###
+
 THICK_LINES:	thick_lines.o
 	ld65 -o THICK_LINES thick_lines.o -C $(LINKERSCRIPTS)/apple2_3f5.inc
 
@@ -115,5 +125,5 @@ purple_waves.o:	purple_waves.s
 
 clean:	
 	rm -f *~ *.o *.lst OVAL PURPLE_WAVES ZEBRA JAWS TWIST OVAL_FLIP \
-			THICK_SINE THICK_LINES
+			THICK_SINE THICK_LINES CIRCLE
 
diff --git a/graphics/hgr/plasma/circle.s b/graphics/hgr/plasma/circle.s
new file mode 100644
index 00000000..5d0c4528
--- /dev/null
+++ b/graphics/hgr/plasma/circle.s
@@ -0,0 +1,129 @@
+; circle
+
+; zero page
+GBASL	= $26
+GBASH	= $27
+YY	= $69
+ROW_SUM = $70
+
+HGR_X           = $E0
+HGR_XH          = $E1
+HGR_Y           = $E2
+HGR_COLOR       = $E4
+HGR_PAGE        = $E6
+
+FRAME	= $FC
+SUM	= $FD
+SAVEX	= $FE
+SAVEY	= $FF
+
+; soft-switches
+FULLGR	= $C052
+PAGE1	= $C054
+
+; ROM routines
+
+HGR2	= $F3D8
+HPOSN	= $F411		; (Y,X),(A)  (values stores in HGRX,XH,Y)
+HPLOT0	= $F457		; plot at (Y,X), (A)
+
+	;================================
+	; Clear screen and setup graphics
+	;================================
+thick_sine:
+
+	jsr	HGR2		; set hi-res 140x192, page2, fullscreen
+				; A and Y both 0 at end
+	;==================
+	; create sinetable
+
+	;ldy	#0		; Y is 0
+sinetable_loop:
+	tya							; 2
+	and	#$3f	; wrap sine at 63 entries		; 2
+
+	cmp	#$20
+	php		; save pos/negative for later
+
+	and	#$1f
+
+	cmp	#$10
+	bcc	sin_left		; blt
+
+sin_right:
+	; sec	carry should be set here
+	eor	#$FF
+	adc	#$20			; 32-X
+sin_left:
+	tax
+	lda	sinetable_base,X				; 4+
+
+	plp
+	bcc	sin_done
+
+sin_negate:
+	; carry set here
+	eor	#$ff
+	adc	#0		; FIXME: this makes things off by 1
+
+sin_done:
+	sta	sinetable,Y
+
+	iny
+	bne	sinetable_loop
+
+
+	;============================
+	; main loop
+	;============================
+
+draw_circle:
+
+
+	ldx	#0
+	stx	SAVEX
+
+circle_loop:
+	lda	SAVEX
+	clc
+	adc	#$10
+	tax
+	lda	sinetable,X
+	clc
+	adc	#$80
+	sta	SAVEY
+
+
+	ldx	SAVEX
+	lda	sinetable,X
+;	asl
+	; $60 is midscreen
+	adc	#$60
+
+	ldx	SAVEY
+	ldy	#0
+
+	jsr	HPLOT0		; plot at (Y,X), (A)
+
+	inc	SAVEX
+
+	bne	circle_loop
+
+done:
+
+blah:
+
+	jmp	blah
+
+
+sinetable_base:
+; this is actually (32*sin(x))
+.byte $00,$03,$06,$09,$0C,$0F,$11,$14
+.byte $16,$18,$1A,$1C,$1D,$1E,$1F,$1F
+.byte $20
+
+	; for bot
+	; 3F5 - 7d = 378
+;	jmp	oval
+
+sinetable=$6000