4 files changed, 69 insertions, 40 deletions
diff --git a/include/gnuradio/block.hpp b/include/gnuradio/block.hpp
index 23274b1..bcce34a 100644
--- a/include/gnuradio/block.hpp
+++ b/include/gnuradio/block.hpp
@@ -22,6 +22,7 @@
 #include <gnuradio/tags.hpp>
 #include <vector>
 #include <string>
+#include <boost/range.hpp> //iterator range
 
 namespace gnuradio
 {
@@ -214,32 +215,14 @@ struct GRAS_API Block : Element
 
     void set_tag_propagation_policy(tag_propagation_policy_t p);
 
-    void add_item_tag(
-        const size_t which_output, const Tag &tag
-    );
-
-    void add_item_tag(
-        const size_t which_output,
-        uint64_t abs_offset,
-        const pmt::pmt_t &key,
-        const pmt::pmt_t &value,
-        const pmt::pmt_t &srcid=pmt::PMT_F
-    );
+    //! Send a tag to the downstream on the given output port
+    void post_output_tag(const size_t which_output, const Tag &tag);
 
-    void get_tags_in_range(
-        std::vector<Tag> &tags,
-        const size_t which_input,
-        uint64_t abs_start,
-        uint64_t abs_end
-    );
+    //! Iterator return type get_input_tags - stl and boost compliant
+    typedef boost::iterator_range<std::vector<Tag>::const_iterator> TagIter;
 
-    void get_tags_in_range(
-        std::vector<Tag> &tags,
-        const size_t which_input,
-        uint64_t abs_start,
-        uint64_t abs_end,
-        const pmt::pmt_t &key
-    );
+    //! Get an iterator of item tags for the given input
+    TagIter get_input_tags(const size_t which_input = 0);
 
     /*******************************************************************
      * Work related routines from basic block
diff --git a/include/gnuradio/gr_block.h b/include/gnuradio/gr_block.h
index 7328dd1..8e0c40e 100644
--- a/include/gnuradio/gr_block.h
+++ b/include/gnuradio/gr_block.h
@@ -80,6 +80,26 @@ struct GRAS_API gr_block : gnuradio::Block
         gr_vector_void_star &output_items
     );
 
+    void add_item_tag(
+        const size_t which_output, const gr_tag_t &tag
+    );
+
+    void add_item_tag(
+        const size_t which_output,
+        uint64_t abs_offset,
+        const pmt::pmt_t &key,
+        const pmt::pmt_t &value,
+        const pmt::pmt_t &srcid=pmt::PMT_F
+    );
+
+    void get_tags_in_range(
+        std::vector<gr_tag_t> &tags,
+        const size_t which_input,
+        uint64_t abs_start,
+        uint64_t abs_end,
+        const pmt::pmt_t &key = pmt::pmt_t()
+    );
+
     unsigned history(void) const;
 
     void set_history(unsigned history);
diff --git a/include/gnuradio/gr_tags.h b/include/gnuradio/gr_tags.h
index e4c9508..cb268da 100644
--- a/include/gnuradio/gr_tags.h
+++ b/include/gnuradio/gr_tags.h
@@ -19,6 +19,27 @@
 
 #include <gnuradio/tags.hpp>
 
-typedef gnuradio::Tag gr_tag_t;
+struct GRAS_API gr_tag_t
+{
+
+    //! the item \p tag occurred at (as a uint64_t)
+    uint64_t offset;
+
+    //! the key of \p tag (as a PMT symbol)
+    pmt::pmt_t key;
+
+    //! the value of \p tag (as a PMT)
+    pmt::pmt_t value;
+
+    //! the source ID of \p tag (as a PMT)
+    pmt::pmt_t srcid;
+
+    //! Comparison function to test which tag, \p x or \p y, came first in time
+    static inline bool offset_compare(
+        const gr_tag_t &x, const gr_tag_t &y
+    ){
+        return x.offset < y.offset;
+    }
+};
 
 #endif /*INCLUDED_GR_TAGS_H*/
diff --git a/include/gnuradio/tags.hpp b/include/gnuradio/tags.hpp
index d8414d8..c8eafba 100644
--- a/include/gnuradio/tags.hpp
+++ b/include/gnuradio/tags.hpp
@@ -18,34 +18,39 @@
 #define INCLUDED_GNURADIO_TAGS_HPP
 
 #include <gnuradio/gras.hpp>
+#include <boost/operators.hpp>
+
+//TODO -- this is a stub for the PMC libray
 #include <gruel/pmt.h>
+typedef pmt::pmt_t PMC;
+typedef pmt::pmt_t PMCC;
 
 namespace gnuradio
 {
 
-struct GRAS_API Tag
+struct GRAS_API Tag : boost::less_than_comparable<Tag>
 {
+    //! Make an empty tag with null members
+    Tag(void);
 
-    //! the item \p tag occurred at (as a uint64_t)
-    uint64_t offset;
+    //! Make a tag from parameters to initialize the members
+    Tag(const uint64_t &offset, const PMCC &key, const PMCC &value, const PMCC &srcid = PMCC());
 
-    //! the key of \p tag (as a PMT symbol)
-    pmt::pmt_t key;
+    //! the absolute item count associated with this tag
+    uint64_t offset;
 
-    //! the value of \p tag (as a PMT)
-    pmt::pmt_t value;
+    //! A symbolic name identifying the type of tag
+    PMCC key;
 
-    //! the source ID of \p tag (as a PMT)
-    pmt::pmt_t srcid;
+    //! The value of this tag -> the sample metadata
+    PMCC value;
 
-    //! Comparison function to test which tag, \p x or \p y, came first in time
-    static inline bool offset_compare(
-        const Tag &x, const Tag &y
-    ){
-        return x.offset < y.offset;
-    }
+    //! The optional source ID -> something unique
+    PMCC srcid;
 };
 
+GRAS_API bool operator<(const Tag &lhs, const Tag &rhs);
+
 } //namespace gnuradio
 
 #endif /*INCLUDED_GNURADIO_TAGS_HPP*/