Case 1: Conditional Cascade Port - 2023.2 English

Vitis Tutorials: AI Engine

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2023.2 English

In this design, a graph is instantiated with a template parameter. Depending on parameter values, a kernel with an input cascade port, an output cascade port, both of them, or none of them is declared as the kernel of the graph. If there is no cascade output port, a streaming output port is declared. As the number of ports depends on the parameter value, the graph will expose a variable number of ports.

template<bool HAS_CASCADE_IN, bool HAS_CASCADE_OUT>
struct SubGraph: public graph
    input_port strmIn;
    typename std::conditional<!HAS_CASCADE_OUT,output_port,int>::type strmOut;
    typename std::conditional<HAS_CASCADE_IN, input_port, int>::type cascIn;
    typename std::conditional<HAS_CASCADE_OUT, output_port, int>::type cascOut;

    kernel     k1;

        if constexpr (HAS_CASCADE_IN && HAS_CASCADE_OUT)
            k1 = kernel::create(k0_cascin_cascout);
            connect(k1.out[0], cascOut);

        else if constexpr (HAS_CASCADE_IN)
            k1 = kernel::create(k0_cascin);
            connect(k1.out[0], strmOut);

        else if constexpr (HAS_CASCADE_OUT)
            k1 = kernel::create(k0_cascout);
            connect(k1.out[0], cascOut);

            k1 = kernel::create(k0);
            connect(k1.out[0], strmOut);

        source(k1) = "kernels.cpp";
        runtime<ratio>(k1) = 0.6;

You can instantiate multiple sub-graphs with various parameters in order to create the complete graph. The testcase of the tutorial is the following:

struct TestGraph: public graph
    SubGraph<false,false> sub0;
    SubGraph<false,true> sub1;
    SubGraph<true,true> sub2;
    SubGraph<true,false> sub3;

    input_plio plioIns[4];
    output_plio plioOuts[2];

        for(int i=0;i<4;i++)
            plioIns[i] = input_plio::create("plio_ins"+std::to_string(i), plio_32_bits, "data/input"+std::to_string(i)+".txt", 100, true);
        plioOuts[0] = output_plio::create("plio_outs0", plio_64_bits, "data/output0.txt", 125.5);
        plioOuts[1] = output_plio::create("plio_outs1", plio_64_bits, "data/output1.txt", 125.5);

        connect(plioIns[0].out[0], sub0.strmIn);
        connect(plioIns[1].out[0], sub1.strmIn);
        connect net2(plioIns[2].out[0], sub2.strmIn);
        connect net3(plioIns[3].out[0], sub3.strmIn);

        fifo_depth(net2) = 32;
        fifo_depth(net3) = 128;

        connect(sub1.cascOut, sub2.cascIn);
        connect(sub2.cascOut, sub3.cascIn);

        connect(sub0.strmOut, plioOuts[0].in[0]);
        connect(sub3.strmOut, plioOuts[1].in[0]);


Four sub-graphs are instantiated with various parameters and then connected together. The graph as shown by the AMD Vitis™ Analyzer is:

No Image

Type make CASE=1 clean data aie aieviz to get this visualization.