Changeset 3563Tweet

Timestamp:

Jul 22, 2009, 2:09:34 PM (11 years ago)

Author:

Sam Hocevar

Message:

Improve the median filter performance.

File:

• libpipi/trunk/pipi/filter/median.c (modified) (1 diff)

libpipi/trunk/pipi/filter/median.c

@@ -29 +29 @@
 static int cmpint(void const *i1, void const *i2)
 {
-    return *(double const *)i1 < *(double const *)i2;
+    /* On Linux amd64, this is 20 to 30 % faster than using a real
+     * comparison (which wouldn't work on Windows since it expects both
+     * negative and positive values), a ternary operator, or floats instead
+     * of doubles. */
+    union { int32_t i; double d; } u;
+    u.d = *(double const *)i1 - *(double const *)i2;
+    return u.i;
 }