Re: [Discuss-gnuradio] Accessing the uhd_usrp object

[M. Ranganathan]

Marcus,

Looking around I don't see where the pointer to the block is made globally visible. I am inclined to add some code to the make method to register the shared pointer in a global variable when the method is called. Since my application has only a single USRP block (source and sink), there's no danger of overwriting something.

My problem is this:

I have python code that creates the blocks and strings them together etc. but I want to actually access the created block from c++ code (in the mac block implementation).

Let me know if I am seriously astray.

Thanks again for your help.

On Thu, Nov 14, 2013 at 9:52 AM, Marcus Müller <address@hidden> wrote:

In GR 3.7, the shared pointer is usually blockname::sptr;

I can't really point you to a very good example, but when you call
top_block.connect(src, sink) in C++, you're giving it spointers :)

As I said, whenever you make a block, you actually get a shared pointer to that instance, and not the object itself.

On 14.11.2013 15:39, M. Ranganathan wrote:

Marcus,

Thanks for your reply. What will the shared pointer be called. I see stuff like this in the code:

GR_SWIG_BLOCK_MAGIC2(uhd, usrp_source)
GR_SWIG_BLOCK_MAGIC2(uhd, usrp_sink)
GR_SWIG_BLOCK_MAGIC2(uhd, amsg_source)

Presumably, that generates a structure that is registered as a global pointer. So in my mac, I want something like

extern ....

At the risk of asking for too much help, can you give me some guidance or point me to a fragment of code somewhere that does this sort of thing.

Thanks,

Ranga

On Thu, Nov 14, 2013 at 4:06 AM, Marcus Müller <address@hidden> wrote:

Hi Ranga,

that's what pointers are for, after all. Just do it! Thanks to the make()-magic you basically always have a smart shared pointer instead of an block object (unless you really try to break the system ;) ).

Just a quick note though: MAC is usually timing-relevant. Timed commands might not work as you expect, so please be aware that calling set_command_time on your source might break functionality since there is no out-of-order execution.

Greetings,
Marcus

On 14.11.2013 01:26, M. Ranganathan wrote:

Hello all!

I want to write a block that can directly access the uhd_usrp_source. This block is a mac block hence it is up on the food chain and far away from uhd_usrp_source in terms of its processing function. What is a good way of passing it a handle to the usrp_source ?

I can think of some hacks (such as a static global pointer where the uhd_usrp_source C++ object registers itself) but it seems ugly to me to take that route. Is there a better way to access global objects from within a block implementation.

Thanks in advance for any help.

Regards,

Ranga

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