2 files changed, 12 insertions, 5 deletions
diff --git a/gr-blocks/lib/random_pdu_impl.cc b/gr-blocks/lib/random_pdu_impl.cc
index 0ae800a167..6efed0664d 100644
--- a/gr-blocks/lib/random_pdu_impl.cc
+++ b/gr-blocks/lib/random_pdu_impl.cc
@@ -32,12 +32,12 @@ namespace gr {
   namespace blocks {
 
     random_pdu::sptr
-    random_pdu::make(int min_items, int max_items, char byte_mask)
+    random_pdu::make(int min_items, int max_items, char byte_mask, int length_modulo)
     {
-      return gnuradio::get_initial_sptr(new random_pdu_impl(min_items, max_items, byte_mask));
+      return gnuradio::get_initial_sptr(new random_pdu_impl(min_items, max_items, byte_mask, length_modulo));
     }
 
-    random_pdu_impl::random_pdu_impl(int min_items, int max_items, char byte_mask)
+    random_pdu_impl::random_pdu_impl(int min_items, int max_items, char byte_mask, int length_modulo)
       :	block("random_pdu",
 		 io_signature::make (0, 0, 0),
 		 io_signature::make (0, 0, 0)),
@@ -45,11 +45,16 @@ namespace gr {
 	d_brange(0, 255),
 	d_rvar(d_rng, d_urange),
 	d_bvar(d_rng, d_brange),
-    d_mask(byte_mask)
+    d_mask(byte_mask),
+    d_length_modulo(length_modulo)
     {
       message_port_register_out(PDU_PORT_ID);
       message_port_register_in(pmt::mp("generate"));
       set_msg_handler(pmt::mp("generate"), boost::bind(&random_pdu_impl::generate_pdu, this, _1));
+      if(length_modulo < 1)
+        throw std::runtime_error("length_module must be >= 1");
+      if(max_items < length_modulo)
+        throw std::runtime_error("max_items must be >= to length_modulo");
     }
 
     bool
@@ -64,6 +69,7 @@ namespace gr {
     {
       // pick a random vector length
       int len = d_rvar();
+      len = std::max(d_length_modulo, len - len%d_length_modulo);
 
       // fill it with random bytes
       std::vector<unsigned char> vec(len);
diff --git a/gr-blocks/lib/random_pdu_impl.h b/gr-blocks/lib/random_pdu_impl.h
index 9cb34c775d..88b218f9f5 100644
--- a/gr-blocks/lib/random_pdu_impl.h
+++ b/gr-blocks/lib/random_pdu_impl.h
@@ -39,9 +39,10 @@ namespace gr {
       boost::variate_generator< boost::mt19937, boost::uniform_int<> > d_rvar; // pdu length
       boost::variate_generator< boost::mt19937, boost::uniform_int<> > d_bvar; // pdu contents
       char d_mask;
+      int d_length_modulo;
 
     public:
-      random_pdu_impl(int min_items, int max_items, char byte_mask);
+      random_pdu_impl(int min_items, int max_items, char byte_mask, int length_modulo);
 
       bool start();
       void output_random();