Asynchronous Scalar RTP - 2023.2 English

Vitis Tutorials: AI Engine

Document ID
XD100
Release Date
2023-11-29
Version
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(k.in[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:

gr.run(4);
gr.update(gr.value,10);

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.

initial_value(k.in[1])=10;

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;
	
ghdl.run(ITERATION);
ghdl.update("gr.k.in[1]",10);