2007-11-06 Tomas Frydrych <tf@o-hand.com>

* clutter/clutter-fixed.h:
	Added CLUTTER_SQRTI_ARG_MAX, CLUTTER_SQRTI_5_PERCENT,
	CLUTTER_SQRTI_10_PERCENT expressing clutter_sqrti limits.
	Stripped trailing whitespace.

        * clutter/clutter-fixed.c:
	(clutter_sqrti):
	Updated documentation, stripped trailing whitespace.

        * clutter/clutter-behaviour-path.c:
	(node_distance):
	Use clib sqrt if clutter_sqrti() precission would be worse than
	10%.
	Stripped trailing whitespace.

ChangeLog

@@ -1,3 +1,20 @@
+2007-11-06  Tomas Frydrych  <tf@o-hand.com>
+
+        * clutter/clutter-fixed.h:
+	Added CLUTTER_SQRTI_ARG_MAX, CLUTTER_SQRTI_5_PERCENT,
+	CLUTTER_SQRTI_10_PERCENT expressing clutter_sqrti limits.
+	Stripped trailing whitespace.
+
+        * clutter/clutter-fixed.c:
+	(clutter_sqrti):
+	Updated documentation, stripped trailing whitespace.
+
+        * clutter/clutter-behaviour-path.c:
+	(node_distance):
+	Use clib sqrt if clutter_sqrti() precission would be worse than
+	10%.
+	Stripped trailing whitespace.
+
 2007-11-06  Emmanuele Bassi  <ebassi@openedhand.com>
 
 	* clutter/clutter-layout.h: Add commodity macros to test for

clutter/clutter-behaviour-path.c

@@ -117,18 +117,28 @@ static gint
 node_distance (const ClutterKnot *begin,
                const ClutterKnot *end)
 {
+  gint t;
+
   g_return_val_if_fail (begin != NULL, 0);
   g_return_val_if_fail (end != NULL, 0);
 
   if (clutter_knot_equal (begin, end))
         return 0;
 
-#if 1
-  return clutter_sqrti ((end->x - begin->x) * (end->x - begin->x) +
-			(end->y - begin->y) * (end->y - begin->y));
+  t = (end->x - begin->x) * (end->x - begin->x) +
+    (end->y - begin->y) * (end->y - begin->y);
+
+  /*
+   * If we are using limited precision sqrti implementation, fallback on
+   * clib sqrt if the precission would be less than 10%
+   */
+#if INT_MAX > CLUTTER_SQRTI_ARG_10_PERCENT
+  if (t <= CLUTTER_SQRTI_ARG_10_PERCENT)
+    return clutter_sqrti (t);
+  else
+    return CLUTTER_FLOAT_TO_INT(sqrt(t));
 #else
-  return CLUTTER_FLOAT_TO_INT(sqrt((end->x - begin->x) * (end->x - begin->x) +
-				   (end->y - begin->y) * (end->y - begin->y)));
+    return clutter_sqrti (t);
 #endif
 }
 

clutter/clutter-fixed.c

@@ -608,7 +608,9 @@ clutter_sqrtx (ClutterFixed x)
  *
  * This function is about 10x faster than clib sqrt() on x86, and (this is
  * not a typo!) more than 800x faster on ARM without FPU. It's error is < 5%
- * for arguments < 132 and < 10% for arguments < 5591.
+ * for arguments < #CLUTTER_SQRTI_ARG_5_PERCENT and < 10% for arguments <
+ * #CLUTTER_SQRTI_ARG_10_PERCENT. The maximum argument that can be passed to
+ * this function is CLUTTER_SQRTI_ARG_MAX.
  *
  * Return value: integer square root.
  *

clutter/clutter-fixed.h

@@ -316,6 +316,47 @@ ClutterFixed clutter_tani (ClutterAngle angle);
  */
 #define clutter_cosi(angle) (clutter_sini ((angle) + 256))
 
+/**
+ * CLUTTER_SQRTI_ARG_MAX
+ *
+ * Maximum argument that can be passed to #clutter_sqrti function.
+ *
+ * Since: 0.6
+ */
+#ifndef __SSE2__
+#define CLUTTER_SQRTI_ARG_MAX 0x3fffff
+#else
+#define CLUTTER_SQRTI_ARG_MAX INT_MAX
+#endif
+
+/**
+ * CLUTTER_SQRTI_ARG_5_PERCENT
+ *
+ * Maximum argument that can be passed to #clutter_sqrti for which the
+ * resulting error is < 5%
+ *
+ * Since: 0.6
+ */
+#ifndef __SSE2__
+#define CLUTTER_SQRTI_ARG_5_PERCENT  131
+#else
+#define CLUTTER_SQRTI_ARG_5_PERCENT INT_MAX
+#endif
+
+/**
+ * CLUTTER_SQRTI_ARG_10_PERCENT
+ *
+ * Maximum argument that can be passed to #clutter_sqrti for which the
+ * resulting error is < 10%
+ *
+ * Since: 0.6
+ */
+#ifndef __SSE2__
+#define CLUTTER_SQRTI_ARG_10_PERCENT 5590
+#else
+#define CLUTTER_SQRTI_ARG_10_PERCENT INT_MAX
+#endif
+
 ClutterFixed clutter_sqrtx (ClutterFixed x);
 gint         clutter_sqrti (gint         x);