Re: [Discuss-gnuradio] About Polymorphic types in gnuradio

[Marcus Müller]

Sorry, forgot about that; also, to make matters worse: "different blocks" also means "different threads", so this is not only a data integrity, but especially a multithreading horror.

On 06.01.2016 17:30, Tom Rondeau wrote:

On Wed, Jan 6, 2016 at 11:23 AM, Marcus Müller <address@hidden> wrote:

Ah, so it's a uniform vector of _u_signed _8_bit integers.
Try pmt::u8vector_ref(VECT, k), where k is the index of the element you want to get. To modify, use pmt::u8vector_set(pmt_t, index,value).

Since your pmt is really just a wrapper around memory-contiguous uint8_ts , you can also "cheat" and directly use the uint8_t* pmt::u8vector_writable_elements(pmt_t v, size_t & len) method, that will give you a C-array/pointer to the first element.

This is not recommended, though. Vectors are unique in the PMT world as they are actually writable. However, if multiple blocks have access to the same PMT vector, you can have thread contention issues when reading and writing.

Better to get the elements as a copy using "std::vector<uint8_t> v = pmt::u8vector_elements(VECT)", manipulate that, and create a new PMT. It's less efficient, but safer.

Tom

 

All these functions are described on
https://gnuradio.org/doc/doxygen/namespacepmt.html#a73605a64c44ec7f12f5f84bb98e2cae3
as linked from the page I mentioned below.

Best regards,
Marcus

On 06.01.2016 17:13, Gabriel Pechiarovich wrote:

I'm using message strobe to send the data in the Message PMt parameter I used:

pmt.cons(pmt.make_dict(), pmt.make_u8vector(8,0x42 ))

then comes my block, and to read the output i'm using Message Debug block.

2016-01-06 10:55 GMT-05:00 Marcus Müller <address@hidden>:

Hi Gabriel,

do you know what kind of PMT VECT is? pmt_t is a container, and might contain a lot of different things.
Is it a pmt::vector, or a pmt::uniform_vector, or a list, or something else?

For an overview, I'd like to point you to the polymorphic types page in the GNU Radio manual [1].

Best regards,
Marcus

[1] https://gnuradio.org/doc/doxygen/page_pmt.html

On 06.01.2016 16:10, Gabriel Pechiarovich wrote:

Hi, I've been working in oot modules in gnuradio for a while, but recently I've been trying to program blocks who can handle messages.

I've extracted the input data and replicated it at the output, like this:

pmt::pmt_t META = pmt::car(PDU);

pmt::pmt_t VECT = pmt::cdr(PDU);

        std::cout << "Vect: " << VECT<< '\n';

message_port_pub(pmt::mp("out_pdu"), pmt::cons(META, VECT));

But I can't understand how to handle VECT, I want to change the VECT values; add some values, basicaly operate this VECT.

If anyone can help me I'll be gratefull.

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Gabriel Pechiarovich Salas

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Gabriel Pechiarovich Salas

Red Dragon Games

Designers and game developers

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