Moved fixed point multiplication and rounding into an asm module.

git-svn-id: svn://svn.cc65.org/cc65/trunk@4447 b7a2c559-68d2-44c3-8de9-860c34a00d81

include/tgi.h

@@ -218,6 +218,14 @@ void __fastcall__ tgi_ellipse (int x, int y, unsigned char rx, unsigned char ry)
  * drawing color.
  */
 
+void __fastcall__ tgi_arc (int x, int y, unsigned char rx, unsigned char ry,
+                           unsigned sa, unsigned ea);
+/* Draw an ellipse arc with center at x/y and radii rx/ry using the current
+ * drawing color. The arc covers the angle between sa and ea (startangle and
+ * endangle), which must be in the range 0..360 (otherwise the function may
+ * bevave unextectedly).
+ */
+
 void __fastcall__ tgi_bar (int x1, int y1, int x2, int y2);
 /* Draw a bar (a filled rectangle) using the current color. */