add some documentation to vrp.h

[r27234]

diff --git a/include/libfirm/vrp.h b/include/libfirm/vrp.h
index 53e3454..68bdf69 100644 (file)
--- a/include/libfirm/vrp.h
+++ b/include/libfirm/vrp.h
@@ -30,16 +30,17 @@
 #define VRP_H
 
 enum range_types {
-       VRP_UNDEFINED,
-       VRP_RANGE,
-       VRP_ANTIRANGE,
-       VRP_VARYING
+       VRP_UNDEFINED, /* No information could be derived so far */
+       VRP_RANGE, /* bottom and top form a range, including both values */
+       VRP_ANTIRANGE, /* range from bottom to top can not be, but borders might
+                                         be */
+       VRP_VARYING /* information can not be derived */
 };
 
 enum range_ops {
-       VRP_NONE,
-       VRP_ADD,
-       VRP_SUB
+       VRP_NONE, /* range is defined absolute */
+       VRP_ADD, /* range + range_node are the possible values */
+       VRP_SUB /* range - range_node are the possible values */
 };
 
 /**