diff --git a/lsflib/src/not.c b/lsflib/src/not.c
new file mode 100644
--- /dev/null
+++ b/lsflib/src/not.c
@@ -0,0 +1,18 @@
+/*
+ *  $Id: not.c 94 2008-04-05 01:27:30Z mbroeker $
+ * $URL: http://localhost/svn/c/lsflib/trunk/src/not.c $
+ *
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+char *not (char *s)
+{
+    int i;
+
+    for (i = 0; i < strlen (s); i++)
+        s[i] = ~s[i];
+
+    return s;
+}