Index: trunk/src_plugins/lib_netmap/placement.h
===================================================================
--- trunk/src_plugins/lib_netmap/placement.h	(revision 35035)
+++ trunk/src_plugins/lib_netmap/placement.h	(revision 35036)
@@ -2,8 +2,11 @@
 #include "data.h"
 #include "ht_subc.h"
 
+/* Build a hash of subcircuit-to-prototype. Effectively a local library
+   of unique footprint prototypes */
+
 typedef struct {
-	htscp_t subcs;
+	htscp_t subcs;   /* value is a normalized subc prototype */
 	pcb_board_t *pcb;
 	pcb_data_t data; /* temp buffer to place prototype subcs in */
 } pcb_placement_t;
@@ -10,4 +13,6 @@
 
 void pcb_placement_init(pcb_placement_t *ctx, pcb_board_t *pcb);
 void pcb_placement_uninit(pcb_placement_t *ctx);
+
+/* Iterate all subcircuits in data and build ctx->subcs hash */
 void pcb_placement_build(pcb_placement_t *ctx, pcb_data_t *data);