George - please reply to the list, not individuals. You'll get your problem
solved faster that way, too.

You can try out your block with a vector source in GRC
https://wiki.gnuradio.org/index.php/Vector_Source.

Also, the existing QA code for the vector source should give you an idea
how to use it in Python. Most of the QA code is written in Python rather
than C++.

https://github.com/gnuradio/gnuradio/blob/master/gr-blocks/python/blocks/qa_vector_sink_source.py



On Sun, Jun 21, 2020 at 7:48 PM George Edwards <[email protected]>
wrote:

> Hi Jeff,
>
> Thanks for the response. Please bear with me a little because of my
> newness to gnuradio.
> I looked up vector source and tagging and found the following for a tagged
> list: [int offset,  pmt key, pmt value, pmt srcid]
>
> In my case my input vector is:: src_data = array([1, 0, 1, 0,...1,,1])
> with 10 values. Do I write the syntax as follows for the QA test code:
> gr::tag_t(int 0, pmt "packet_len", pmt 10, pmt src_data)???
>
> Thanks for the help.
>
> Regards,
> George
>
> On Sun, Jun 21, 2020 at 5:09 PM Jeff Long <[email protected]> wrote:
>
>> If you are trying to create a test vector to feed into a block that needs
>> a tag named "length", you can use a Vector Source. That block allows you to
>> define a vector of data along with tags.
>>
>> On Sun, Jun 21, 2020 at 6:38 PM George Edwards <[email protected]>
>> wrote:
>>
>>> Hello,
>>>
>>> New to gnuradio and I am making an OOT CRC8 module to take a tagged bit
>>> stream (1's and 0's) and generate the CRC and attach the CRC to the end of
>>> the data and pass it on to the next block. Also, I am encapsulating both
>>> the generator and check sum in same block using a boolean variable "check"
>>> to determine operation.
>>>
>>> In QA test I get the following error:
>>> gr::log :FATAL: my_crc8_bb0 - Missing a required length tag on port 0 at
>>> item #0.
>>> thread [thread-per-block[1] < block my crc8_bb(2)>] Missing length tag
>>>
>>> I modified the QA test vector by writing the length of the input string
>>> of 1's and 0's as the first element in the input data array, but it gave
>>> the same error as typed above.
>>>
>>> Questions:
>>> Q1. How do I write in the input test vector, or what do I add to what I
>>> already have to make the module aware of the tag length?
>>>
>>> Q2. In the my_crc8_bb_impl.cc file in the tagged stream method, I
>>> specified the tag name as "packet_len". In the signal processing in this
>>> .cc file, I assume the value of packet_len is available to me for use as a
>>> parameter and I used it. Are there some other things I need to do in this
>>> "my_crc8_bb_impl.cc file" to make the module more aware of input tagged
>>> stream data (maybe I am not binding "packet_len" properly)?
>>>
>>> I greatly appreciate any help!
>>>
>>> Regards,
>>> George
>>>
>>

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