Hi.
Thanks a lot for your time to read.
I read the two links that you shared to me, Marcus. Thanks a lot for your
help. But i still have a problem.
I've implemented as follows:
- I create, the output, input and the handler:
message_port_register_out(pmt::mp("out_threshold"));
message_port_register_in(pmt::mp("in_threshold"));
set_msg_handler(pmt::mp("in_threshold"),
boost::bind(&sync_short_impl::set_msg, this, _1));
- I create, the next function to handle the inputs
void set_msg(pmt::pmt_t msg) { d_msg= msg;
dout << "Nueva lectura : " << d_msg << " ninput: " << std::endl;
if (pmt::is_integer(d_msg)) {
d_threshold = (double) pmt::to_long(d_msg);
} else if (pmt::is_real(d_msg)) {
d_threshold = pmt::to_double(d_msg);
} else {
// We really expected an integer or a double here, so we don't know what
to do
throw std::runtime_error("expected an integer!");
}
}
- In the block i linked the input and the output, just to check that the
function set_msg(), works.
[image: Imágenes integradas 3]
- I compile the c++ codes, etc... all that is necessary.
- I write the output as follows (that's working, i checked that with a
message debug):
message_port_pub(pmt::mp("out_threshold"), pmt::cons(pmt::PMT_NIL,
pmt::from_double(d_threshold)));
- When i start the flowgraph, the block put in the output a PMT message,
after that, as it is linked with the input, the message go to the input
port. When it is recevied, the function set_msg is launched, but the type
of the number in the PMT is not recognized as double. *Here is my
problem, I don't understand why it is happening, because the PMT that I put
in the output is build from a double, then it is supposed, the one that i
received is too a double. What do you think?*
[image: Imágenes integradas 2]
Thanks in advance.
Best regards,
Cristian
2017-06-26 12:45 GMT-05:00 Marcus Müller <marcus.muel...@ettus.com>:
> Hi Cristian,
>
> you need to subscribe a *handler* to the message port. See:
>
> https://wiki.gnuradio.org/index.php/Guided_Tutorial_
> Programming_Topics#5.3.2_Adding_Message_Passing_to_the_Code
>
> It's absolutely up to you what kind of PMT you're publishing over a
> message port, but it's canonical to have a PMT dict that maps
>
> pmt::mp("propertyname") -> pmt::whateversuitsyourproperty.
>
> As an example, see what the gr-uhd blocks accept [1]
>
> Best regards,
>
> Marcus
>
> [1] https://gnuradio.org/doc/doxygen/page_uhd.html#uhd_command_syntax
> On 06/26/2017 07:35 PM, Cristian Rodríguez wrote:
>
> Hi all,
>
> I'm not sure about how to read and write PMT ports from and to local
> variables. I'm going to expose what i'm doing, and if someone can help me i
> would be very greatful.
>
> I've created an input and an output of PMT type.
>
> message_port_register_in(pmt::pmt_t in_threshold)
> message_port_register_out(pmt::pmt_t out_threshold)
>
> Now i want to read the port, and save the data in a local variable, do
> operations with that variable, and later write it in the output,
>
> I create the variables,
>
> double d_threshold;
> pmt::pmt_t target;
>
>
>
> *I read it, I don't know how to do it. But I suppose: *
> message_port_sub(pmt::pmt_t
> <https://gnuradio.org/doc/doxygen/namespacepmt.html#ab4b70d9293452eb74dd07c670e6811fa>
> in_threshold,pmt::pmt_t
> <https://gnuradio.org/doc/doxygen/namespacepmt.html#ab4b70d9293452eb74dd07c670e6811fa>
> target);
> d_threshold= pmt::to_double
> <https://gnuradio.org/doc/doxygen/namespacepmt.html#a0f58166fe9f449249f5de7dc7b3ab754>
> (target);
>
> And, I think i can write it as follows:
>
> msg=pmt::from_double
> <https://gnuradio.org/doc/doxygen/namespacepmt.html#ad20c287c509e8470d03d1c8e97fea12d>
> (d_threshold);
> message_port_pub(pmt::pmt_t
> <https://gnuradio.org/doc/doxygen/namespacepmt.html#ab4b70d9293452eb74dd07c670e6811fa>
> out_threshold,pmt::pmt_t
> <https://gnuradio.org/doc/doxygen/namespacepmt.html#ab4b70d9293452eb74dd07c670e6811fa>
> msg);
>
> What do you think, i've seen several examples, and they do this,
> message_port_pub(pmt::mp("symbols"), pmt::cons(pmt::make_dict(),
> pmt::init_c32vector(48, symbols)));
>
> But I don't understand why it is necessary to use pmt::make_dict().
>
> Thanks in advance.
>
> Best regards,
>
> Cristian
>
>
>
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