Multicast Support - 2025.1 English - UG1079

Various multicast scenarios are supported in the graph, such as from a buffer to multiple buffers, from stream to multiple streams, from input_plio to multiple buffers, etc. This section lists the supported types of multicast from a single source to multiple destinations. For additional details on input_plio/output_plio, and input_gmio/output_gmio, see Graph Programming Model.

When multiple streams are connected to the same source, the data is sent to all the destination ports at the same time and is only sent when all destinations are ready to receive data. This might cause stream stall or design hang if the FIFO depth of the stream connections are not deep enough.

The following multicast example shows scenario number 10 from above table. Source and both destinations are stream.

In this graph.h code snippet, two sub-graphs named _graph0 and _graph1 are defined within the top graph named top_graph. This ensures that sending data to all destination ports at the same time.

class _graph0: public adf::graph {
private:
    adf::kernel kr;
public:
    adf::port<input> instream;
    adf::port<output> outstream;
    _graph0() {
        kr = adf::kernel::create(compute0);
        adf::runtime<ratio>(kr) = 0.9;
        adf::source(kr) = "compute0.cc";
        adf::connect<adf::stream> n0(instream, kr.in[0]);
        adf::connect<adf::stream> n1(kr.out[0], outstream);
    }
};

class _graph1: public adf::graph {
private:
    adf::kernel kr;
public:
    adf::port<input> instream;
    adf::port<output> outstream;
    _graph1() {
        kr = adf::kernel::create(compute1);
        adf::runtime<ratio>(kr) = 0.9;
        adf::source(kr) = "compute1.cc";
        adf::connect<adf::stream> n0(instream, kr.in[0]);
        adf::connect<adf::stream> n1(kr.out[0], outstream);
    }
};

class top_graph: public adf::graph {
private:

public:
    _graph0 g0;
    _graph1 g1;
    adf::input_plio  instream;
    adf::output_plio outstream0;
    adf::output_plio outstream1;
    top_graph()
    {
        instream   = adf::input_plio::create("aie_brodcast_0_S_AXIS",
                         adf::plio_32_bits,
                         "data/input.txt");
        outstream0 = adf::output_plio::create("aie_graph0_outstream",
                         adf::plio_32_bits,
                         "data/output0.txt");
        outstream1 = adf::output_plio::create("aie_graph1_outstream",
                         adf::plio_32_bits,
                         "data/output1.txt");

        adf::connect<adf::stream> n0(instream.out[0], g0.instream);
        adf::connect<adf::stream> n1(instream.out[0], g1.instream);
        adf::connect<adf::stream> n2(g0.outstream, outstream0.in[0]);
        adf::connect<adf::stream> n3(g1.outstream, outstream1.in[0]);
    }
};

In this graph.cpp code snippet, the graph calls are invoked from the top graph so all sub-graphs are receiving the same data at the same time.

top_graph top_g;

#if defined  (__AIESIM__) || defined(__X86SIM__)
int main () {
        top_g.init();
        top_g.run(3);
        top_g.wait();
        top_g.end();
        return 0;
}
#endif