[Discuss-gnuradio] gr_io_signature question

[Garrett Mcgrath]

Ok I’ve decided on somewhat of a revisit of my code.  Taking Eric’s advice I’m going to reimplement the code in a more flowgraph based behavior.  After a vector is brought into the system by the MPI (my UDP interface system) some values will be stripped and the pay load will be passed to a first code block that converts the values from an array of U8’s to an array of unsigned shorts that represent the physical bit value (each U8 will have 8 values representing their binary equivalents.).  This will then be parsed into 2 streams (broken at the midpoint of the array into 2 separate streams) and passed out to the encoding block.  This Aloumoti encoder will then use a bit from row 0 and 1 from row 1 and convert them into a 2X2 matrix and pass this out the other end (so I’m assuming a 1:2 or 2:4 interpolation is needed here).  My question is how to utilize ‘gr_io_signature’ in the class derivation to create the 2 output streams, how to return on these 2 steams and then access them on the other end.

 

I know the python should look something like

 

#get values from UDP here

 

MPI_SRC=gr.vector_source(src_data) #the stripped vector

BIT_CONVERT=my.Bit_Vector()

ALOUMOTI_ENCODER=my.Aloumoti()

TX0PAYLOAD=gr.vector_sink()

TX1PAYLOAD=gr.vector_sink()

 

fg.connect(MPI_SRC, BIT_CONVERTER)

fg.connect((BIT_CONVERTER,0), (ALOUMOTI_ENCODER,0))

fg.connect((BIT_CONVERTER,1), (ALOUMOTI_ENCODER,1))

fg.connect((ALOUMOTI_ENCODER,0), TX0PAYLOAD)#these are sink currently so I can check the behavior of my flow graph system.

fg.connect((ALOUMOTI_ENCODER,1), TX1PAYLOAD)

 

at least this is the impression I get from the documentation.

 

However the aloumoti needs these 2 streams in combination to create the output streams, how (in c) do I specify that there are 2 inputs and then proceed to access those inputs in the C system?  I’m already aware it will in some way involve the min_in, min_out, etc. variables and their use in generating an IO signature.

 

Is it involved in the declaration of the in and out variables at the beginning of the ‘work’ function:

Specifically do I use something akin to:

const float *in0= (const float *) input_items[0];

const float *in1= (const float *) input_items[1];

 

Any help would be greatly appreciated.

 

-Garrett McGrath