Index: alien_formats/easyeda/arc_testbench/arc_sed.c
===================================================================
--- alien_formats/easyeda/arc_testbench/arc_sed.c	(revision 39206)
+++ alien_formats/easyeda/arc_testbench/arc_sed.c	(revision 39207)
@@ -9,12 +9,42 @@
 	b = __tmp__; \
 } while(0)
 
-static int arc_sed_90(double sx, double sy, double ex, double ey, double deg, double *cx, double *cy, double *r, double *srad, double *erad)
+#define GEN_OUTPUT() \
+do { \
+	*cx_out = cx; \
+	*cy_out = cy; \
+	*r_out = r; \
+	*srad = atan2(sy - cy, sx - cx); \
+	*erad = atan2(ey - cy, ex - cx); \
+} while(0)
+
+/* Optimized solver for 90 degree: consider the right triangle from
+   cx;cy, ex;ey, sx;sy. Knowing the chord length this yields r. Consider half
+   of this triangle, cutting from middle of the chord, also a right
+   triangle: chord side length known, hypotenuse is r -> distance from mx;my
+   to cx;cy. */
+static int arc_sed_90(double sx, double sy, double ex, double ey, double deg, double *cx_out, double *cy_out, double *r_out, double *srad, double *erad)
 {
-	return -5;
+	double r, cx, cy;
+	double mx, my, mr;
+	double chlen, chvx, chvy, chnx, chny, chl2; /* chord */
+
+	mx = (sx + ex) / 2.0; my = (sy + ey) / 2.0;
+	chvx = ex - sx; chvy = ey - sy;
+	chlen = sqrt(chvx*chvx + chvy*chvy); chl2 = chlen/2.0;
+	chvx /= chlen; chvy /= chlen;
+	chnx = -chvy; chny = chvx;
+
+	r  = sqrt(chlen*chl2);  /* sqrt(chlen*chlen/2) */
+	mr = sqrt(r*r - chl2*chl2);
+	cx = mx + chnx * mr; cy = my + chny * mr;
+
+	GEN_OUTPUT();
+
+	return 0;
 }
 
-static int arc_sed_180(double sx, double sy, double ex, double ey, double deg, double *cx, double *cy, double *r, double *srad, double *erad)
+static int arc_sed_180(double sx, double sy, double ex, double ey, double deg, double *cx_out, double *cy_out, double *r_out, double *srad, double *erad)
 {
 	return -5;
 }
@@ -25,7 +55,7 @@
 }
 
 /* Generic for angle smaller than 180; draw chord between start and end, the
-   middle of the cord is mx;my. Consider the right angle triangle mx;my
+   middle of the cord is mx;my. Consider the right triangle mx;my
    cx;cy and ex;ey; the central angle is deg/2, the side at chord is chl2.
    This yields radius and the side from mx;my to cx;cy. */
 static int arc_sed_small(double sx, double sy, double ex, double ey, double deg, double *cx_out, double *cy_out, double *r_out, double *srad, double *erad)
@@ -46,12 +76,7 @@
 	mr = sqrt(r*r - chl2*chl2);
 	cx = mx + chnx * mr; cy = my + chny * mr;
 
-	*cx_out = cx;
-	*cy_out = cy;
-	*r_out = r;
-
-	*srad = atan2(sy - cy, sx - cx);
-	*erad = atan2(ey - cy, ex - cx);
+	GEN_OUTPUT();
 	return 0;
 }