WriteBlocksInPython¶

This is experimental work. The code can be found here:
http://gnuradio.org/cgit/jblum.git/log/?h=next

An advanced coding guide can be found here: BlocksCodingGuide

This work allows one to write a gnuradio block entirely in python
by overloading work() and doing the processing with numpy arrays.

The following interfaces are available:

• gr.basic_block - overload general work, call consume
• gr.sync_block - overload work, return num output items
• gr.decim_block - set decimation factor, overload work
• gr.interp_block - set interpolation factor, overload work

Some quick examples¶

Look at the QA code here for how to use:
http://gnuradio.org/cgit/jblum.git/tree/gnuradio-core/src/python/gnuradio/gr/qa_block_gateway.py?h=next

Examples of message passing in QA code:
http://gnuradio.org/cgit/jblum.git/tree/gnuradio-core/src/python/gnuradio/gr/qa_msg_passing.py?h=next

Replacing example pkt.py with message passing framework:
http://gnuradio.org/cgit/jblum.git/tree/gr-digital/python/pkt2.py?h=next

IO Signatures¶

The block input and output signature should be a list of dtype arguments,
where each dtype argument can be passed into the numpy.dtype constructor.
Alternatively, if an IO has zero ports, you can pass None as the argument.

Some IO signature examples:

• Block with no output streams: None or []
• Each item is a complex float: [numpy.complex64]
• Each item is a 2x float vector: [(numpy.float32, 2)]
• Multiple input streams: [numpy.float32, numpy.int32]

Overloading work¶

Overload the work method in your class as follows:

def work(self, input_items, output_items):
    #TODO insert work code here...
    return len(output_items[0])

input_items and output_items is a list of numpy arrays.
Each numpy array in the items list represents a port.
The user should read from input_items and write to output_items.
And the user should return the number of output_items produced.

For those unfamiliar with numpy, read the following:

output_items[0] = my_data #incorrect, this only changes array references
output_items[0][:] = my_data #correct, this assigns to the output buffer