From 930b6e56cd5c999b2b529ee9e19bbb18135f7b0b Mon Sep 17 00:00:00 2001
From: Peter Tillema <petertillema@solcon.nl>
Date: Tue, 8 Mar 2022 12:50:54 +0100
Subject: [PATCH 1/9] Add ellipse routines

---
 src/graphx/graphx.asm | 372 ++++++++++++++++++++++++++++++++++++++++++
 src/graphx/graphx.h   |  50 ++++++
 2 files changed, 422 insertions(+)

diff --git a/src/graphx/graphx.asm b/src/graphx/graphx.asm
index d41307d07..b57469dfd 100644
--- a/src/graphx/graphx.asm
+++ b/src/graphx/graphx.asm
@@ -133,6 +133,13 @@ library 'GRAPHX', 11
 ; v10 functions
 ;-------------------------------------------------------------------------------
 	export gfx_CopyRectangle
+;-------------------------------------------------------------------------------
+; v11 functions
+;-------------------------------------------------------------------------------
+	export gfx_Ellipse
+	export gfx_Ellipse_NoClip
+	export gfx_FillEllipse
+	export gfx_FillEllipse_NoClip
 
 ;-------------------------------------------------------------------------------
 LcdSize            := ti.lcdWidth*ti.lcdHeight
@@ -636,6 +643,7 @@ _SetPixel_NoWait:
 	ld	hl,-ti.lcdHeight
 	add	hl,de
 	ret	c			; return if out of bounds
+_SetPixel_NoClip_NoWait:
 	ld	hl,(CurrentBuffer)
 	add	hl,bc
 	ld	d,ti.lcdWidth / 2
@@ -1135,6 +1143,370 @@ assert .LcdSizeH and ti.lcdIntLNBU
 	dec	sp			; sp -= 3 to match pop hl later
 	jr	_WriteWaitQuickSMC
 
+;-------------------------------------------------------------------------------
+gfx_FillEllipse_NoClip:
+	ld	hl,gfx_HorizLine_NoClip
+	db	$FD			; ld hl,* -> ld iy,*
+
+;-------------------------------------------------------------------------------
+gfx_FillEllipse:
+	ld	hl,gfx_HorizLine
+	ld	(_ellipse_line_routine_1),hl
+	ld	(_ellipse_line_routine_2),hl
+	ld	hl,_ellipse_draw_line
+	ld	(_ellipse_loop_draw_2),hl
+	ld	(_ellipse_loop_draw_3),hl
+	ld	hl,_ellipse_ret
+	ld	(_ellipse_loop_draw_1),hl
+	jr	_Ellipse
+	
+;-------------------------------------------------------------------------------
+gfx_Ellipse_NoClip:
+	ld	hl,_SetPixel_NoClip_NoWait
+	db	$FD		; ld hl,* -> ld iy,*
+
+;-------------------------------------------------------------------------------
+gfx_Ellipse:
+	ld	hl,_SetPixel_NoWait
+	ld	(_ellipse_pixel_routine_1),hl
+	ld	(_ellipse_pixel_routine_2),hl
+	ld	(_ellipse_pixel_routine_3),hl
+	ld	(_ellipse_pixel_routine_4),hl
+	ld	hl,_ellipse_draw_pixels
+	ld	(_ellipse_loop_draw_1),hl
+	ld	(_ellipse_loop_draw_3),hl
+	ld	hl,_ellipse_ret
+	ld	(_ellipse_loop_draw_2),hl
+
+el_x		:= 3		; Current X coordinate of the ellipse
+el_y		:= 6		; Current Y coordinate of the ellipse
+el_a2		:= 9		; X radius squared
+el_b2		:= 12		; Y radius squared
+el_fa2		:= 15		; X radius squared * 4
+el_fb2		:= 18		; Y radius squared * 4
+el_sigma	:= 21		; Sigma
+el_sigma_1	:= 24		; Offset to be added to sigma in loop 1
+el_sigma_2	:= 27		; Offset to be added to sigma in loop 2
+el_temp1	:= 30		; X radius as "int" instead of "uint8_t"
+el_comp_a	:= 33		; b2 * x
+el_comp_b	:= 36		; a2 * y
+el_sigma_diff1	:= 39		; Offset to be added to sigma in loop 1
+el_sigma_diff2	:= 42		; Offset to be added to sigma in loop 2
+
+_Ellipse:
+; Draws an ellipse, either filled or not, either clipped or not
+; Arguments:
+;  arg0 : X coordinate (ix+6)
+;  arg1 : Y coordinate (ix+9)
+;  arg2 : X radius (ix+12)
+;  arg3 : Y radius (ix+15)
+; Returns:
+;  None
+	push	ix
+	ld	ix,0
+	add	ix,sp
+	lea	hl,ix - 42
+	ld	sp,hl
+	
+; First, setup all the variables
+	ld	a,(ix + 12)
+	or	a,a
+	ret	z				; Make sure X radius is not 0
+	ld	l,a
+	ld	h,a
+	mlt	hl
+	ld	(ix - el_a2),hl			; int a2 = a * a;
+	add	hl,hl
+	ld	(ix - el_sigma_diff2),hl	; Save a2 * 2 for later
+	add	hl,hl
+	ld	(ix - el_fa2),hl		; int fa2 = 4 * a2;
+	ld	a,(ix + 15)
+	or	a,a
+	ret	z				; Make sure Y radius is not 0
+	ld	e,a
+	ld	d,1
+	mlt	de
+	ld	(ix - el_y),de			; int y = b;
+	ld	hl,(ix - el_a2)
+	ld	d,l
+	ld	l,e
+	mlt	de
+	mlt	hl
+	add	hl,hl
+	add	hl,hl
+	add	hl,hl
+	add	hl,hl
+	add	hl,hl
+	add	hl,hl
+	add	hl,hl
+	add	hl,hl
+	add	hl,de
+	add	hl,hl
+	add	hl,hl
+	ex	de,hl
+	ld	hl,(ix - el_fa2)
+	or	a,a
+	sbc	hl,de
+	ld	(ix - el_sigma_1),hl		; int sigma_add_1 = fa2 * (1 - b);
+	ld	l,a
+	ld	h,a
+	mlt	hl
+	ld	(ix - el_b2),hl			; int b2 = b * b;
+	add	hl,hl
+	ld	(ix - el_sigma_diff1),hl	; Save b2 * 2 for later
+	add	hl,hl
+	ld	(ix - el_fb2),hl		; int fb2 = 4 * b2;
+	ld	c,a
+	ld	b,2
+	mlt	bc
+	or	a,a
+	sbc	hl,hl
+	ld	(ix - el_x),hl			; int x = 0;
+	ld	(ix - el_comp_a),hl
+	inc	hl
+	sbc	hl,bc
+	ld	bc,(ix - el_a2)
+	call	_MultiplyHLBC
+	ld	bc,(ix - el_b2)
+	add	hl,bc
+	add	hl,bc
+	ld	(ix - el_sigma),hl		; int sigma = 2 * b2 + a2 * (1 - 2 * b);
+	ld	e,(ix + 12)
+	ld	d,1
+	mlt	de
+	ld	(ix - el_temp1),de		; Save int a for later
+	or	a,a
+	sbc	hl,hl
+	inc	hl
+	sbc	hl,de
+	ld	bc,(ix - el_fb2)
+	call	_MultiplyHLBC
+	ld	(ix - el_sigma_2),hl		; int sigma_add_2 = fb2 * (1 - a);
+
+	ld	hl,(ix - el_a2)
+	ld	bc,(ix - el_y)
+	call	_MultiplyHLBC
+	ld	(ix - el_comp_b),hl
+	
+	wait_quick
+
+.main_loop1:
+	call	0
+_ellipse_loop_draw_1 := $-3
+
+; Eventually change sigma and y
+	ld	hl,(ix - el_sigma)
+	add	hl,hl
+	jr	c,.loop1_jump			; if (sigma >= 0) {
+
+	call	0
+_ellipse_loop_draw_2 := $-3
+
+	ld	hl,(ix - el_sigma)		; sigma += sigma_add_1;
+	ld	de,(ix - el_sigma_1)
+	add	hl,de
+	ld	(ix - el_sigma),hl
+	ld	hl,(ix - el_fa2)
+	add	hl,de
+	ld	(ix - el_sigma_1),hl		; sigma_add_1 += fa2;
+	ld	hl, (ix - el_y)
+	dec	hl
+	ld	(ix - el_y),hl			; y--;
+	ld	hl,(ix - el_comp_b)
+	ld	de,(ix - el_a2)
+	or	a,a
+	sbc	hl,de
+	ld	(ix - el_comp_b),hl
+.loop1_jump:					; }
+; Change sigma and increment x
+	ld	hl,(ix - el_sigma_diff1)
+	ld	de,(ix - el_fb2)
+	add	hl,de
+	ld	(ix - el_sigma_diff1),hl
+	ld	de,(ix - el_sigma)
+	add	hl,de
+	ld	(ix - el_sigma),hl		; sigma += b2 * (4 * x + 6);
+	ld	hl,(ix - el_x)
+	inc	hl
+	ld	(ix - el_x),hl			; x++;
+
+; Update the comparison operands
+	ld	hl,(ix - el_comp_a)
+	ld	de,(ix - el_b2)
+	add	hl,de
+	ld	(ix - el_comp_a),hl
+	ld	de,(ix - el_comp_b)
+
+; And compare
+	ld	bc,0x800000			; b2 * x <= a2 * y so hl <= de
+	add	hl,bc
+	ex	de,hl				; de <= hl
+	add	hl,bc
+	or	a,a
+	sbc	hl,de
+	jq	nc,.main_loop1
+
+; Update few variables for the next loop
+	ld	hl, (ix - el_temp1)
+	ld	(ix - el_x),hl			; x = a
+	ld	e,l
+	or	a,a
+	sbc	hl,hl
+	ld	(ix - el_y),hl			; y = 0
+	ld	(ix - el_comp_a),hl
+	ld	d,2
+	mlt	de
+	inc	hl
+	sbc	hl,de
+	ld	bc,(ix - el_b2)
+	call	_MultiplyHLBC
+	ld	de,(ix - el_a2)
+	add	hl,de
+	add	hl,de
+	ld	(ix - el_sigma), hl
+
+	ld	hl,(ix - el_b2)
+	ld	bc,(ix - el_temp1)
+	call	_MultiplyHLBC
+	ld	(ix - el_comp_b),hl
+
+.main_loop2:
+	call	0
+_ellipse_loop_draw_3 := $-3
+
+; Eventually update sigma and x
+	ld	hl,(ix - el_sigma)
+	add	hl,hl
+	jr	c,.loop2_jump			; if (sigma >= 0) {
+	ld	hl,(ix - el_sigma)
+	ld	de,(ix - el_sigma_2)
+	add	hl,de
+	ld	(ix - el_sigma),hl		; sigma += sigma_add_2;
+	ld	hl,(ix - el_fb2)
+	add	hl,de
+	ld	(ix - el_sigma_2),hl		; sigma_add_2 += fb2;
+	ld	hl, (ix - el_x)
+	dec	hl
+	ld	(ix - el_x),hl			; x--;
+	ld	hl,(ix - el_comp_b)
+	ld	de,(ix - el_b2)
+	or	a,a
+	sbc	hl,de
+	ld	(ix - el_comp_b),hl
+.loop2_jump:
+; Change sigma and increment y
+	ld	hl,(ix - el_sigma_diff2)
+	ld	de,(ix - el_fa2)
+	add	hl,de
+	ld	(ix - el_sigma_diff2),hl
+	ld	de,(ix - el_sigma)
+	add	hl,de
+	ld	(ix - el_sigma),hl		; sigma += a2 * (4 * y + 6);
+	ld	hl,(ix - el_y)
+	inc	hl
+	ld	(ix - el_y),hl			; y++;
+	ld	hl,(ix - el_comp_a)
+	ld	de,(ix - el_a2)
+	add	hl,de
+	ld	(ix - el_comp_a),hl
+
+; Compare the boolean operators
+	ld	de,(ix - el_comp_b)
+	ld	bc,0x800000
+	add	hl,bc
+	ex	de,hl
+	add	hl,bc
+	or	a,a
+	sbc	hl,de
+	jq	nc,.main_loop2
+
+	ld	sp,ix
+	pop	ix
+_ellipse_ret:
+	ret
+
+_ellipse_draw_pixels:
+; bc = x coordinate
+; e = y coordinate
+	ld	hl,(ix + 9)
+	ld	de,(ix - el_y)
+	add	hl,de
+	ex	de,hl			; yc + y
+	push	de
+	ld	hl,(ix + 6)
+	ld	bc,(ix - el_x)
+	add	hl,bc
+	push	hl
+	pop	bc			; xc + x
+	call	_SetPixel_NoWait
+_ellipse_pixel_routine_1 := $-3
+	pop	de
+	ld	hl,(ix + 6)
+	ld	bc,(ix - el_x)
+	or	a,a
+	sbc	hl,bc
+	push	hl
+	pop	bc			; xc - x
+	push	bc
+	call	_SetPixel_NoWait
+_ellipse_pixel_routine_2 := $-3
+	pop	bc
+	ld	hl,(ix + 9)
+	ld	de,(ix - el_y)
+	or	a,a
+	sbc	hl,de
+	push	hl
+	pop	bc			; yc - y
+	push	bc
+	call	_SetPixel_NoWait
+_ellipse_pixel_routine_3 := $-3
+	pop	bc
+	ld	hl,(ix + 6)
+	ld	de,(ix - el_x)
+	add	hl,de
+	ex	de,hl			; xc + x
+	jp	_SetPixel_NoWait
+_ellipse_pixel_routine_4 := $-3
+
+_ellipse_draw_line:
+	ld	hl,(ix - el_x)
+	add	hl,hl
+	push	hl
+	ld	hl,(ix + 9)
+	ld	de,(ix - el_y)
+	or	a,a
+	sbc	hl,de
+	push	hl
+	ld	hl,(ix + 6)
+	ld	de,(ix - el_x)
+	or	a,a
+	sbc	hl,de
+	push	hl
+	call	0
+_ellipse_line_routine_1 := $-3
+	pop	hl
+	pop	hl
+	pop	hl
+	ld	hl,(ix - el_x)
+	add	hl,hl
+	push	hl
+	ld	hl,(ix + 9)
+	ld	de,(ix - el_y)
+	add	hl,de
+	push	hl
+	ld	hl,(ix + 6)
+	ld	de,(ix - el_x)
+	or	a,a
+	sbc	hl,de
+	push	hl
+	call	0
+_ellipse_line_routine_2 := $-3
+	pop	hl
+	pop	hl
+	pop	hl
+	ret
+	
+
 ;-------------------------------------------------------------------------------
 gfx_Circle:
 ; Draws a clipped circle outline
diff --git a/src/graphx/graphx.h b/src/graphx/graphx.h
index 7dad1321a..5a631b868 100644
--- a/src/graphx/graphx.h
+++ b/src/graphx/graphx.h
@@ -35,6 +35,7 @@
  * @author Jacob "jacobly" Young
  * @author Zachary "Runer112" Wassall
  * @author Patrick "tr1p1ea" Prendergast
+ * @author Peter "PT_" Tillema
  * @author "grosged"
  */
 
@@ -756,6 +757,55 @@ void gfx_FillCircle_NoClip(uint24_t x,
 #define gfx_Circle_NoClip(x, y, radius) \
 gfx_Circle((x), (y), (radius))
 
+/**
+ * Draws an unclipped filled ellipse.
+ *
+ * This is measured from the top left origin of the screen.
+ * Performs faster than using gfx_FillEllipse, but can cause corruption if used outside the bounds of the screen.
+ * @param x X coordinate.
+ * @param y Y coordinate.
+ * @param a The horizontal radius of the ellipse.
+ * @param b The vertical radius of the ellipse.
+ */
+void gfx_FillEllipse_NoClip(int x,
+                            int y,
+                            int a,
+							int b);
+
+/**
+ * Draws a filled ellipse.
+ *
+ * This is measured from the top left origin of the screen.
+ * @param x X coordinate.
+ * @param y Y coordinate.
+ * @param a The horizontal radius of the ellipse.
+ * @param b The vertical radius of the ellipse.
+ */
+void gfx_FillEllipse(int x, int y, int a, int b);
+
+/**
+ * Draws an unclipped ellipse.
+ *
+ * This is measured from the top left origin of the screen.
+ * Performs faster than using gfx_FillEllipse, but can cause corruption if used outside the bounds of the screen.
+ * @param x X coordinate.
+ * @param y Y coordinate.
+ * @param a The horizontal radius of the ellipse.
+ * @param b The vertical radius of the ellipse.
+ */
+void gfx_Ellipse_NoClip(int x, int y, int a, int b);
+
+/**
+ * Draws an ellipse.
+ *
+ * This is measured from the top left origin of the screen.
+ * @param x X coordinate.
+ * @param y Y coordinate.
+ * @param a The horizontal radius of the ellipse.
+ * @param b The vertical radius of the ellipse.
+ */
+void gfx_Ellipse(int x, int y, int a, int b);
+
 /**
  * Draws a clipped polygon outline.
  *

From 101c2ed13e384fdd95c47b099c50388f88372633 Mon Sep 17 00:00:00 2001
From: Peter Tillema <petertillema@solcon.nl>
Date: Tue, 8 Mar 2022 12:58:14 +0100
Subject: [PATCH 2/9] Fix return when radius is 0

---
 src/graphx/graphx.asm | 10 +++++++---
 src/graphx/graphx.h   |  5 +----
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/graphx/graphx.asm b/src/graphx/graphx.asm
index b57469dfd..c2f5cb907 100644
--- a/src/graphx/graphx.asm
+++ b/src/graphx/graphx.asm
@@ -1210,8 +1210,12 @@ _Ellipse:
 	
 ; First, setup all the variables
 	ld	a,(ix + 12)
-	or	a,a
-	ret	z				; Make sure X radius is not 0
+	jr	nz,.valid_x_radius
+.return:
+	ld	sp,ix
+	pop	ix
+	ret
+.valid_x_radius:
 	ld	l,a
 	ld	h,a
 	mlt	hl
@@ -1222,7 +1226,7 @@ _Ellipse:
 	ld	(ix - el_fa2),hl		; int fa2 = 4 * a2;
 	ld	a,(ix + 15)
 	or	a,a
-	ret	z				; Make sure Y radius is not 0
+	jr	z,.return			; Make sure Y radius is not 0
 	ld	e,a
 	ld	d,1
 	mlt	de
diff --git a/src/graphx/graphx.h b/src/graphx/graphx.h
index 5a631b868..32aa64b22 100644
--- a/src/graphx/graphx.h
+++ b/src/graphx/graphx.h
@@ -767,10 +767,7 @@ gfx_Circle((x), (y), (radius))
  * @param a The horizontal radius of the ellipse.
  * @param b The vertical radius of the ellipse.
  */
-void gfx_FillEllipse_NoClip(int x,
-                            int y,
-                            int a,
-							int b);
+void gfx_FillEllipse_NoClip(int x, int y, int a, int b);
 
 /**
  * Draws a filled ellipse.

From 14196a9ff01732658d4a4e3833f3560de1fca8b5 Mon Sep 17 00:00:00 2001
From: Peter Tillema <petertillema@solcon.nl>
Date: Tue, 8 Mar 2022 12:59:40 +0100
Subject: [PATCH 3/9] Fix comment tabs

---
 src/graphx/graphx.asm | 58 +++++++++++++++++++++----------------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/src/graphx/graphx.asm b/src/graphx/graphx.asm
index c2f5cb907..0afed996d 100644
--- a/src/graphx/graphx.asm
+++ b/src/graphx/graphx.asm
@@ -1219,18 +1219,18 @@ _Ellipse:
 	ld	l,a
 	ld	h,a
 	mlt	hl
-	ld	(ix - el_a2),hl			; int a2 = a * a;
+	ld	(ix - el_a2),hl		; int a2 = a * a;
 	add	hl,hl
-	ld	(ix - el_sigma_diff2),hl	; Save a2 * 2 for later
+	ld	(ix - el_sigma_diff2),hl; Save a2 * 2 for later
 	add	hl,hl
-	ld	(ix - el_fa2),hl		; int fa2 = 4 * a2;
+	ld	(ix - el_fa2),hl	; int fa2 = 4 * a2;
 	ld	a,(ix + 15)
 	or	a,a
-	jr	z,.return			; Make sure Y radius is not 0
+	jr	z,.return		; Make sure Y radius is not 0
 	ld	e,a
 	ld	d,1
 	mlt	de
-	ld	(ix - el_y),de			; int y = b;
+	ld	(ix - el_y),de		; int y = b;
 	ld	hl,(ix - el_a2)
 	ld	d,l
 	ld	l,e
@@ -1251,21 +1251,21 @@ _Ellipse:
 	ld	hl,(ix - el_fa2)
 	or	a,a
 	sbc	hl,de
-	ld	(ix - el_sigma_1),hl		; int sigma_add_1 = fa2 * (1 - b);
+	ld	(ix - el_sigma_1),hl	; int sigma_add_1 = fa2 * (1 - b);
 	ld	l,a
 	ld	h,a
 	mlt	hl
-	ld	(ix - el_b2),hl			; int b2 = b * b;
+	ld	(ix - el_b2),hl		; int b2 = b * b;
 	add	hl,hl
 	ld	(ix - el_sigma_diff1),hl	; Save b2 * 2 for later
 	add	hl,hl
-	ld	(ix - el_fb2),hl		; int fb2 = 4 * b2;
+	ld	(ix - el_fb2),hl	; int fb2 = 4 * b2;
 	ld	c,a
 	ld	b,2
 	mlt	bc
 	or	a,a
 	sbc	hl,hl
-	ld	(ix - el_x),hl			; int x = 0;
+	ld	(ix - el_x),hl		; int x = 0;
 	ld	(ix - el_comp_a),hl
 	inc	hl
 	sbc	hl,bc
@@ -1274,18 +1274,18 @@ _Ellipse:
 	ld	bc,(ix - el_b2)
 	add	hl,bc
 	add	hl,bc
-	ld	(ix - el_sigma),hl		; int sigma = 2 * b2 + a2 * (1 - 2 * b);
+	ld	(ix - el_sigma),hl	; int sigma = 2 * b2 + a2 * (1 - 2 * b);
 	ld	e,(ix + 12)
 	ld	d,1
 	mlt	de
-	ld	(ix - el_temp1),de		; Save int a for later
+	ld	(ix - el_temp1),de	; Save int a for later
 	or	a,a
 	sbc	hl,hl
 	inc	hl
 	sbc	hl,de
 	ld	bc,(ix - el_fb2)
 	call	_MultiplyHLBC
-	ld	(ix - el_sigma_2),hl		; int sigma_add_2 = fb2 * (1 - a);
+	ld	(ix - el_sigma_2),hl	; int sigma_add_2 = fb2 * (1 - a);
 
 	ld	hl,(ix - el_a2)
 	ld	bc,(ix - el_y)
@@ -1301,27 +1301,27 @@ _ellipse_loop_draw_1 := $-3
 ; Eventually change sigma and y
 	ld	hl,(ix - el_sigma)
 	add	hl,hl
-	jr	c,.loop1_jump			; if (sigma >= 0) {
+	jr	c,.loop1_jump		; if (sigma >= 0) {
 
 	call	0
 _ellipse_loop_draw_2 := $-3
 
-	ld	hl,(ix - el_sigma)		; sigma += sigma_add_1;
+	ld	hl,(ix - el_sigma)	; sigma += sigma_add_1;
 	ld	de,(ix - el_sigma_1)
 	add	hl,de
 	ld	(ix - el_sigma),hl
 	ld	hl,(ix - el_fa2)
 	add	hl,de
-	ld	(ix - el_sigma_1),hl		; sigma_add_1 += fa2;
+	ld	(ix - el_sigma_1),hl	; sigma_add_1 += fa2;
 	ld	hl, (ix - el_y)
 	dec	hl
-	ld	(ix - el_y),hl			; y--;
+	ld	(ix - el_y),hl		; y--;
 	ld	hl,(ix - el_comp_b)
 	ld	de,(ix - el_a2)
 	or	a,a
 	sbc	hl,de
 	ld	(ix - el_comp_b),hl
-.loop1_jump:					; }
+.loop1_jump:				; }
 ; Change sigma and increment x
 	ld	hl,(ix - el_sigma_diff1)
 	ld	de,(ix - el_fb2)
@@ -1329,10 +1329,10 @@ _ellipse_loop_draw_2 := $-3
 	ld	(ix - el_sigma_diff1),hl
 	ld	de,(ix - el_sigma)
 	add	hl,de
-	ld	(ix - el_sigma),hl		; sigma += b2 * (4 * x + 6);
+	ld	(ix - el_sigma),hl	; sigma += b2 * (4 * x + 6);
 	ld	hl,(ix - el_x)
 	inc	hl
-	ld	(ix - el_x),hl			; x++;
+	ld	(ix - el_x),hl		; x++;
 
 ; Update the comparison operands
 	ld	hl,(ix - el_comp_a)
@@ -1342,9 +1342,9 @@ _ellipse_loop_draw_2 := $-3
 	ld	de,(ix - el_comp_b)
 
 ; And compare
-	ld	bc,0x800000			; b2 * x <= a2 * y so hl <= de
+	ld	bc,0x800000		; b2 * x <= a2 * y so hl <= de
 	add	hl,bc
-	ex	de,hl				; de <= hl
+	ex	de,hl			; de <= hl
 	add	hl,bc
 	or	a,a
 	sbc	hl,de
@@ -1352,11 +1352,11 @@ _ellipse_loop_draw_2 := $-3
 
 ; Update few variables for the next loop
 	ld	hl, (ix - el_temp1)
-	ld	(ix - el_x),hl			; x = a
+	ld	(ix - el_x),hl		; x = a
 	ld	e,l
 	or	a,a
 	sbc	hl,hl
-	ld	(ix - el_y),hl			; y = 0
+	ld	(ix - el_y),hl		; y = 0
 	ld	(ix - el_comp_a),hl
 	ld	d,2
 	mlt	de
@@ -1381,17 +1381,17 @@ _ellipse_loop_draw_3 := $-3
 ; Eventually update sigma and x
 	ld	hl,(ix - el_sigma)
 	add	hl,hl
-	jr	c,.loop2_jump			; if (sigma >= 0) {
+	jr	c,.loop2_jump		; if (sigma >= 0) {
 	ld	hl,(ix - el_sigma)
 	ld	de,(ix - el_sigma_2)
 	add	hl,de
-	ld	(ix - el_sigma),hl		; sigma += sigma_add_2;
+	ld	(ix - el_sigma),hl	; sigma += sigma_add_2;
 	ld	hl,(ix - el_fb2)
 	add	hl,de
-	ld	(ix - el_sigma_2),hl		; sigma_add_2 += fb2;
+	ld	(ix - el_sigma_2),hl	; sigma_add_2 += fb2;
 	ld	hl, (ix - el_x)
 	dec	hl
-	ld	(ix - el_x),hl			; x--;
+	ld	(ix - el_x),hl		; x--;
 	ld	hl,(ix - el_comp_b)
 	ld	de,(ix - el_b2)
 	or	a,a
@@ -1405,10 +1405,10 @@ _ellipse_loop_draw_3 := $-3
 	ld	(ix - el_sigma_diff2),hl
 	ld	de,(ix - el_sigma)
 	add	hl,de
-	ld	(ix - el_sigma),hl		; sigma += a2 * (4 * y + 6);
+	ld	(ix - el_sigma),hl	; sigma += a2 * (4 * y + 6);
 	ld	hl,(ix - el_y)
 	inc	hl
-	ld	(ix - el_y),hl			; y++;
+	ld	(ix - el_y),hl		; y++;
 	ld	hl,(ix - el_comp_a)
 	ld	de,(ix - el_a2)
 	add	hl,de

From 1e0a5fa1db36c2de045df1df5127d31a5636704d Mon Sep 17 00:00:00 2001
From: Peter Tillema <petertillema@solcon.nl>
Date: Tue, 8 Mar 2022 14:05:52 +0100
Subject: [PATCH 4/9] Fix location of points, fix incorrect nz check

---
 src/graphx/graphx.asm | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/src/graphx/graphx.asm b/src/graphx/graphx.asm
index 0afed996d..4d7d46da5 100644
--- a/src/graphx/graphx.asm
+++ b/src/graphx/graphx.asm
@@ -2,7 +2,7 @@
 include '../include/library.inc'
 ;-------------------------------------------------------------------------------
 
-library 'GRAPHX', 11
+library 'GRAPHX', 12
 
 ;-------------------------------------------------------------------------------
 ; no dependencies
@@ -1210,6 +1210,7 @@ _Ellipse:
 	
 ; First, setup all the variables
 	ld	a,(ix + 12)
+	or	a,a
 	jr	nz,.valid_x_radius
 .return:
 	ld	sp,ix
@@ -1435,14 +1436,14 @@ _ellipse_draw_pixels:
 	ld	hl,(ix + 9)
 	ld	de,(ix - el_y)
 	add	hl,de
-	ex	de,hl			; yc + y
+	ex	de,hl
 	push	de
 	ld	hl,(ix + 6)
 	ld	bc,(ix - el_x)
 	add	hl,bc
 	push	hl
-	pop	bc			; xc + x
-	call	_SetPixel_NoWait
+	pop	bc
+	call	_SetPixel_NoWait	; xc + x, yc + y
 _ellipse_pixel_routine_1 := $-3
 	pop	de
 	ld	hl,(ix + 6)
@@ -1450,26 +1451,26 @@ _ellipse_pixel_routine_1 := $-3
 	or	a,a
 	sbc	hl,bc
 	push	hl
-	pop	bc			; xc - x
+	pop	bc
 	push	bc
-	call	_SetPixel_NoWait
+	call	_SetPixel_NoWait	; xc - x, yc + y
 _ellipse_pixel_routine_2 := $-3
 	pop	bc
 	ld	hl,(ix + 9)
 	ld	de,(ix - el_y)
 	or	a,a
 	sbc	hl,de
-	push	hl
-	pop	bc			; yc - y
-	push	bc
-	call	_SetPixel_NoWait
+	ex	de,hl
+	push	de
+	call	_SetPixel_NoWait	; xc - x, yc - y
 _ellipse_pixel_routine_3 := $-3
-	pop	bc
+	pop	de
 	ld	hl,(ix + 6)
-	ld	de,(ix - el_x)
-	add	hl,de
-	ex	de,hl			; xc + x
-	jp	_SetPixel_NoWait
+	ld	bc,(ix - el_x)
+	add	hl,bc
+	push	hl
+	pop	bc
+	jp	_SetPixel_NoWait	; xc + x, yc - y
 _ellipse_pixel_routine_4 := $-3
 
 _ellipse_draw_line:

From b06ce03e817fe63e9ea9a70e09e17698a457769c Mon Sep 17 00:00:00 2001
From: Peter Tillema <petertillema@solcon.nl>
Date: Wed, 9 Mar 2022 08:56:04 +0100
Subject: [PATCH 5/9] Fix versions in header of graphx.asm

---
 src/graphx/graphx.asm | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/graphx/graphx.asm b/src/graphx/graphx.asm
index 4d7d46da5..c74949107 100644
--- a/src/graphx/graphx.asm
+++ b/src/graphx/graphx.asm
@@ -132,9 +132,13 @@ library 'GRAPHX', 12
 ;-------------------------------------------------------------------------------
 ; v10 functions
 ;-------------------------------------------------------------------------------
-	export gfx_CopyRectangle
+
 ;-------------------------------------------------------------------------------
 ; v11 functions
+;-------------------------------------------------------------------------------
+	export gfx_CopyRectangle
+;-------------------------------------------------------------------------------
+; v12 functions
 ;-------------------------------------------------------------------------------
 	export gfx_Ellipse
 	export gfx_Ellipse_NoClip

From 03efe3b8bffc4d5469fc12051d87d89b2095f4e4 Mon Sep 17 00:00:00 2001
From: Peter Tillema <petertillema@solcon.nl>
Date: Wed, 9 Mar 2022 13:41:43 +0100
Subject: [PATCH 6/9] Clearify wording of x/y coordinates

---
 src/graphx/graphx.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/graphx/graphx.h b/src/graphx/graphx.h
index 32aa64b22..50f3040fb 100644
--- a/src/graphx/graphx.h
+++ b/src/graphx/graphx.h
@@ -762,8 +762,8 @@ gfx_Circle((x), (y), (radius))
  *
  * This is measured from the top left origin of the screen.
  * Performs faster than using gfx_FillEllipse, but can cause corruption if used outside the bounds of the screen.
- * @param x X coordinate.
- * @param y Y coordinate.
+ * @param x X coordinate of the center.
+ * @param y Y coordinate of the center.
  * @param a The horizontal radius of the ellipse.
  * @param b The vertical radius of the ellipse.
  */
@@ -773,8 +773,8 @@ void gfx_FillEllipse_NoClip(int x, int y, int a, int b);
  * Draws a filled ellipse.
  *
  * This is measured from the top left origin of the screen.
- * @param x X coordinate.
- * @param y Y coordinate.
+ * @param x X coordinate of the center.
+ * @param y Y coordinate of the center.
  * @param a The horizontal radius of the ellipse.
  * @param b The vertical radius of the ellipse.
  */
@@ -785,8 +785,8 @@ void gfx_FillEllipse(int x, int y, int a, int b);
  *
  * This is measured from the top left origin of the screen.
  * Performs faster than using gfx_FillEllipse, but can cause corruption if used outside the bounds of the screen.
- * @param x X coordinate.
- * @param y Y coordinate.
+ * @param x X coordinate of the center.
+ * @param y Y coordinate of the center.
  * @param a The horizontal radius of the ellipse.
  * @param b The vertical radius of the ellipse.
  */
@@ -796,8 +796,8 @@ void gfx_Ellipse_NoClip(int x, int y, int a, int b);
  * Draws an ellipse.
  *
  * This is measured from the top left origin of the screen.
- * @param x X coordinate.
- * @param y Y coordinate.
+ * @param x X coordinate of the center.
+ * @param y Y coordinate of the center.
  * @param a The horizontal radius of the ellipse.
  * @param b The vertical radius of the ellipse.
  */

From b16e157055360992ddef84cf6427671bc59f5a81 Mon Sep 17 00:00:00 2001
From: Peter Tillema <petertillema@solcon.nl>
Date: Mon, 14 Mar 2022 12:37:37 +0100
Subject: [PATCH 7/9] Add warning

---
 src/graphx/graphx.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/graphx/graphx.h b/src/graphx/graphx.h
index 50f3040fb..9179ca1a6 100644
--- a/src/graphx/graphx.h
+++ b/src/graphx/graphx.h
@@ -762,6 +762,11 @@ gfx_Circle((x), (y), (radius))
  *
  * This is measured from the top left origin of the screen.
  * Performs faster than using gfx_FillEllipse, but can cause corruption if used outside the bounds of the screen.
+ * 
+ * @warning
+ * When using too large radii (> 128) the upper and lower half of the ellipse might get corrupted due to
+ * integer overflow.
+ * 
  * @param x X coordinate of the center.
  * @param y Y coordinate of the center.
  * @param a The horizontal radius of the ellipse.
@@ -773,6 +778,11 @@ void gfx_FillEllipse_NoClip(int x, int y, int a, int b);
  * Draws a filled ellipse.
  *
  * This is measured from the top left origin of the screen.
+ * 
+ * @warning
+ * When using too large radii (> 128) the upper and lower half of the ellipse might get corrupted due to
+ * integer overflow.
+ * 
  * @param x X coordinate of the center.
  * @param y Y coordinate of the center.
  * @param a The horizontal radius of the ellipse.
@@ -785,6 +795,11 @@ void gfx_FillEllipse(int x, int y, int a, int b);
  *
  * This is measured from the top left origin of the screen.
  * Performs faster than using gfx_FillEllipse, but can cause corruption if used outside the bounds of the screen.
+ * 
+ * @warning
+ * When using too large radii (> 128) the upper and lower half of the ellipse might get corrupted due to
+ * integer overflow.
+ * 
  * @param x X coordinate of the center.
  * @param y Y coordinate of the center.
  * @param a The horizontal radius of the ellipse.
@@ -796,6 +811,11 @@ void gfx_Ellipse_NoClip(int x, int y, int a, int b);
  * Draws an ellipse.
  *
  * This is measured from the top left origin of the screen.
+ * 
+ * @warning
+ * When using too large radii (> 128) the upper and lower half of the ellipse might get corrupted due to
+ * integer overflow.
+ * 
  * @param x X coordinate of the center.
  * @param y Y coordinate of the center.
  * @param a The horizontal radius of the ellipse.

From 77daf5ad0cb58ee3ba563a80b08482c2b3aace30 Mon Sep 17 00:00:00 2001
From: Peter Tillema <petertillema@solcon.nl>
Date: Mon, 14 Mar 2022 12:48:45 +0100
Subject: [PATCH 8/9] Add ellipses to autotest

---
 examples/graphx/shapes/autotest.json | 25 +++++++++++++++++--------
 examples/graphx/shapes/src/main.c    | 19 +++++++++++++++++++
 2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/examples/graphx/shapes/autotest.json b/examples/graphx/shapes/autotest.json
index b72820457..ffde1d779 100644
--- a/examples/graphx/shapes/autotest.json
+++ b/examples/graphx/shapes/autotest.json
@@ -14,7 +14,7 @@
     "delay|100",
     "hashWait|1",
     "key|enter",
-    "hashWait|2",
+	"hashWait|2",
     "key|enter",
     "hashWait|3",
     "key|enter",
@@ -22,10 +22,12 @@
     "key|enter",
     "hashWait|5",
     "key|enter",
-    "delay|2000",
     "hashWait|6",
     "key|enter",
-    "hashWait|7"
+    "delay|2000",
+    "hashWait|7",
+    "key|enter",
+    "hashWait|8"
   ],
   "hashes":
   {
@@ -37,41 +39,48 @@
       "expected_CRCs": [ "8DE8E699" ]
     },
     "2":
+    {
+      "description": "Test ellipse display",
+      "start": "vram_start",
+      "size": "vram_8_size",
+      "expected_CRCs": [ "2138C183" ]
+    },
+    "3":
     {
       "description": "Test rectangle outline display",
       "start": "vram_start",
       "size": "vram_8_size",
       "expected_CRCs": [ "6390F38B" ]
     },
-    "3":
+    "4":
     {
       "description": "Test rectangle fill display",
       "start": "vram_start",
       "size": "vram_8_size",
       "expected_CRCs": [ "163F3B60" ]
     },
-    "4":
+    "5":
     {
       "description": "Test triangle fill display",
       "start": "vram_start",
       "size": "vram_8_size",
       "expected_CRCs": [ "A1154AE5" ]
     },
-    "5":
+    "6":
     {
       "description": "Test line display",
       "start": "vram_start",
       "size": "vram_8_size",
       "expected_CRCs": [ "08AE93E1" ]
     },
-    "6":
+    "7":
     {
       "description": "Test pixel display",
       "start": "vram_start",
       "size": "vram_8_size",
       "expected_CRCs": [ "B6CCDD04" ]
     },
-    "7":
+    "8":
     {
       "description": "Test program exit",
       "start": "vram_start",
diff --git a/examples/graphx/shapes/src/main.c b/examples/graphx/shapes/src/main.c
index 0a4b3f78b..7d0050593 100644
--- a/examples/graphx/shapes/src/main.c
+++ b/examples/graphx/shapes/src/main.c
@@ -40,6 +40,25 @@ int main(void)
 
     /* Waits for a key */
     while (!os_GetCSC());
+	
+	/* Clear the screen */
+    gfx_FillScreen(255);
+	
+	/* Ellipse Drawing */
+	gfx_SetColor(56);
+	for (i = 10; i < 50; i += 2)
+    {
+		gfx_Ellipse_NoClip(100, 100, i, 40);
+	}
+	gfx_SetColor(195);
+	gfx_Ellipse(300, 35, 140, 80);
+	gfx_SetColor(5);
+	gfx_FillEllipse_NoClip(200, 150, 120, 50);
+	gfx_SetColor(210);
+	gfx_FillEllipse(25, 200, 60, 90);
+	
+	/* Waits for a key */
+    while (!os_GetCSC());
 
     /* Clear the screen */
     gfx_FillScreen(255);

From ab90972f2d4704ba26e6b7d3057a118eac0395ef Mon Sep 17 00:00:00 2001
From: Peter Tillema <petertillema@solcon.nl>
Date: Mon, 14 Mar 2022 13:00:32 +0100
Subject: [PATCH 9/9] Fix tabs

---
 examples/graphx/shapes/autotest.json |  2 +-
 examples/graphx/shapes/src/main.c    | 32 ++++++++++++++--------------
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/examples/graphx/shapes/autotest.json b/examples/graphx/shapes/autotest.json
index ffde1d779..b09931c22 100644
--- a/examples/graphx/shapes/autotest.json
+++ b/examples/graphx/shapes/autotest.json
@@ -14,7 +14,7 @@
     "delay|100",
     "hashWait|1",
     "key|enter",
-	"hashWait|2",
+    "hashWait|2",
     "key|enter",
     "hashWait|3",
     "key|enter",
diff --git a/examples/graphx/shapes/src/main.c b/examples/graphx/shapes/src/main.c
index 7d0050593..4fa3a96a1 100644
--- a/examples/graphx/shapes/src/main.c
+++ b/examples/graphx/shapes/src/main.c
@@ -40,24 +40,24 @@ int main(void)
 
     /* Waits for a key */
     while (!os_GetCSC());
-	
-	/* Clear the screen */
+    
+    /* Clear the screen */
     gfx_FillScreen(255);
-	
-	/* Ellipse Drawing */
-	gfx_SetColor(56);
-	for (i = 10; i < 50; i += 2)
+    
+    /* Ellipse Drawing */
+    gfx_SetColor(56);
+    for (i = 10; i < 50; i += 2)
     {
-		gfx_Ellipse_NoClip(100, 100, i, 40);
-	}
-	gfx_SetColor(195);
-	gfx_Ellipse(300, 35, 140, 80);
-	gfx_SetColor(5);
-	gfx_FillEllipse_NoClip(200, 150, 120, 50);
-	gfx_SetColor(210);
-	gfx_FillEllipse(25, 200, 60, 90);
-	
-	/* Waits for a key */
+        gfx_Ellipse_NoClip(100, 100, i, 40);
+    }
+    gfx_SetColor(195);
+    gfx_Ellipse(300, 35, 140, 80);
+    gfx_SetColor(5);
+    gfx_FillEllipse_NoClip(200, 150, 120, 50);
+    gfx_SetColor(210);
+    gfx_FillEllipse(25, 200, 60, 90);
+    
+    /* Waits for a key */
     while (!os_GetCSC());
 
     /* Clear the screen */