1 files changed, 67 insertions, 0 deletions
diff --git a/gr-blocks/python/blocks/msg_meta_to_pair.py b/gr-blocks/python/blocks/msg_meta_to_pair.py
new file mode 100644
index 0000000000..1c6dde2f61
--- /dev/null
+++ b/gr-blocks/python/blocks/msg_meta_to_pair.py
@@ -0,0 +1,67 @@
+#!/usr/bin/env python
+#
+# Copyright 2020 Free Software Foundation, Inc.
+#
+# This file is part of GNU Radio
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+#
+
+from gnuradio import gr
+import pmt
+
+class meta_to_pair(gr.sync_block):
+    """
+    This block converts a metadata dictionary item to a pmt pair that is
+    compatible with other blocks expecting a pair in.  You can specify
+    which item in the incoming metadata to output as a pair and what
+    the pair name is.
+    """
+    def __init__(self, incomingKeyName, outgoingPairName):
+        gr.sync_block.__init__(self, name="meta_to_pair", in_sig=None, out_sig=None)
+
+        self.incomingKeyName = str(incomingKeyName)
+        self.outgoingPairName = str(outgoingPairName)
+
+        self.message_port_register_in(pmt.intern("inmeta"))
+        self.set_msg_handler(pmt.intern("inmeta"), self.msg_handler)
+        self.message_port_register_out(pmt.intern("outpair"))
+
+    def msg_handler(self, msg):
+        if not pmt.is_pair(msg):
+            gr.log.warn("Incoming message is not a pair.  Only pairs are supported.  "
+                        "No message generated.")
+            return
+
+        meta = pmt.to_python(pmt.car(msg))
+
+        if not type(meta) is dict:
+            gr.log.warn("Incoming message does not contain a dictionary.  "
+                        "No message generated.")
+            return
+
+        if not self.incomingKeyName in meta:
+            gr.log.warn("Incoming message dictionary does not contain key %s.  "
+                        "No message generated." % self.incomingKeyName)
+            return
+
+        incomingVal = meta[self.incomingKeyName]
+
+        new_pair = None
+
+        try:
+            new_pair = pmt.cons(pmt.intern(self.outgoingPairName), pmt.to_pmt(incomingVal))
+        except Exception as e:
+            gr.log.error("Cannot construct new message: %s" % str(e))
+            return
+
+        try:
+            self.message_port_pub(pmt.intern("outpair"), new_pair)
+        except Exception as e:
+            gr.log.error("Cannot send message: %s" % str(e))
+            gr.log.error("Incoming dictionary (%s):" % str(type(meta)))
+            gr.log.error(str(meta))
+
+    def stop(self):
+        return True