fix subheader parsing

lib/include/srslte/common/pdu.h

@@ -138,11 +138,10 @@ public:
     do {
       if (nof_subheaders < (int)max_subheaders) {
         ret = subheaders[nof_subheaders].read_subheader(&ptr);
-      }
-    } while (ret && nof_subheaders < (int) max_subheaders);
-    if (nof_subheaders + 1 < (int) max_subheaders) {
         nof_subheaders++;
       }
+    } while (ret && (nof_subheaders + 1) < (int)max_subheaders);
+
     for (int i=0;i<nof_subheaders;i++) {
       subheaders[i].read_payload(&ptr);
     }

lib/src/common/pdu.cc

@@ -122,7 +122,7 @@ uint8_t* sch_pdu::write_packet(srslte::log *log_h)
   sch_subh padding; 
   padding.set_padding();
 
-  if (nof_subheaders <= 0 && nof_subheaders < max_subheaders) {
+  if (nof_subheaders <= 0 && nof_subheaders < (int)max_subheaders) {
     log_h->error("Trying to write packet with invalid number of subheaders (nof_subheaders=%d).\n", nof_subheaders);
     log_h->console("Trying to write packet with invalid number of subheaders (nof_subheaders=%d).\n", nof_subheaders);
     return NULL;