Asynchronous Scalar RTP - 2023.2 English

Vitis Tutorials: AI Engine

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2023.2 English

For asynchronous RTP input, each iteration of the kernel tries to read the newest updated RTP value, but not synchronous to the RTP update.

The test case is async_rtp.

The kernel signature is:

template<int32 NUM>
void vect_add(input_buffer<int32,extents<NUM>>& __restrict in,output_buffer<int32,extents<NUM>>& __restrict out,int32 value);

The RTP specification can be found in aie/graph.h:

using namespace adf;
adf::port<adf::direction::in> value;
adf::connect<adf::parameter>(value, async([1])); 

Note that for RTP input, the default behavior is synchronous. So, it has to specify asynchronous RTP input with keyword async (equivalent to adf::async as namespace adf is used).

The RTP calls for aiesimulator can be found in aie/graph.cpp:;

Note: It requires at least one update of the RTP input. Otherwise, the kernel execution will be stalled. A way to bypass initial RTP update is to set following constraints in the graph code (aie/graph.h). Thus, kernel can start execution asynchronously with the specified initial value.


The host code for HW and HW emulation flows can be found in sw/host.cpp:

auto ghdl=xrt::graph(device,uuid,"gr");
const int ITERATION=4;;