From ed39db99a579342ad354b00f5639258f43528e6d Mon Sep 17 00:00:00 2001
From: Tectu <joel@unormal.org>
Date: Tue, 10 Jul 2012 01:15:31 +0200
Subject: [PATCH] added lcdDrawEllipse() - contributed by Ben William

---
 glcd.c | 28 ++++++++++++++++++++++++++++
 glcd.h |  1 +
 lcd.mk |  1 +
 3 files changed, 30 insertions(+)

diff --git a/glcd.c b/glcd.c
index 8ab87597..683f8a3a 100644
--- a/glcd.c
+++ b/glcd.c
@@ -319,6 +319,34 @@ void lcdDrawCircle(uint16_t x, uint16_t y, uint16_t radius, uint8_t filled, uint
 		} while(a <= b);
 }
 
+void lcdDrawEllipse(uint16_t x, uint16_t y, uint16_t a, uint16_t b, uint16_t color) {
+	int dx = 0, dy = b; /* im I. Quadranten von links oben nach rechts unten */
+	long a2 = a*a, b2 = b*b;
+	long err = b2-(2*b-1)*a2, e2; /* Fehler im 1. Schritt */
+
+	do {
+		lcdDrawPixel(x+dx, y+dy, color); /* I. Quadrant */
+		lcdDrawPixel(x-dx, y+dy, color); /* II. Quadrant */
+		lcdDrawPixel(x-dx, y-dy, color); /* III. Quadrant */
+		lcdDrawPixel(x+dx, y-dy, color); /* IV. Quadrant */
+
+		e2 = 2*err;
+		if(e2 <  (2*dx+1)*b2) {
+			dx++;
+			err += (2*dx+1)*b2;
+		}
+		if(e2 > -(2*dy-1)*a2) {
+			dy--;
+			err -= (2*dy-1)*a2;
+		}
+	} while(dy >= 0); 
+
+	while(dx++ < a) { /* fehlerhafter Abbruch bei flachen Ellipsen (b=1) */
+		lcdDrawPixel(x+dx, y, color); /* -> Spitze der Ellipse vollenden */
+		lcdDrawPixel(x-dx, y, color);
+   }   
+}
+
 void lcdVerticalScroll(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, int16_t lines) {
 	lld_lcdVerticalScroll(x0,y0,x1,y1,lines);
 }
diff --git a/glcd.h b/glcd.h
index 531be901..bb587253 100644
--- a/glcd.h
+++ b/glcd.h
@@ -67,6 +67,7 @@ void lcdDrawLine(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, uint16_t co
 void lcdDrawRect(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, uint8_t filled, uint16_t color);
 void lcdDrawRectString(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, const char* str, font_t font, uint16_t fontColor, uint16_t bkColor);
 void lcdDrawCircle(uint16_t x, uint16_t y, uint16_t radius, uint8_t filled, uint16_t color);
+void lcdDrawEllipse(uint16_t x, uint16_t y, uint16_t a, uint16_t b, uint16_t color);
 
 /* Text Rendering Functions */
 int lcdDrawChar(uint16_t cx, uint16_t cy, char c, font_t font, uint16_t color, uint16_t bkcolor, bool_t tpText);
diff --git a/lcd.mk b/lcd.mk
index 5ba7df1b..6bae4072 100644
--- a/lcd.mk
+++ b/lcd.mk
@@ -8,6 +8,7 @@ LCDSRC = 	$(LCDLIB)/glcd.c \
 			$(LCDLIB)/graph.c \
 			$(LCDLIB)/gui.c \
 			$(LCDLIB)/console.c \
+			$(LCDLIB)/fastMath.c \
 			$(LCD_DRIVERS_SRC)
 
 LCDINC = 	$(LCDLIB) \