Supported High-Level Synthesis Features in the AI Engine Compiler - 2020.2 English - UG1076

The AI Engine compiler supports a subset of high-level synthesis (HLS) interfaces.

The supported input and output data types of HLS functions are:

• hls::stream<ap_axis<N,0,0,0>> and hls::stream<ap_axiu<N,0,0,0>>, where N can be 32, 64, or 128
• hls::stream<ap_int<N>> and hls::stream<ap_uint<N>>, where N can be 32 or 64
• hls::stream<T>, where T can be int, unsigned int, long long, unsigned long long, or float
• hls::stream<std::complex<T>>, where T can be int, short or float

The following scalar run-time parameter (RTP) data types are also supported:

• ap_int<N> and ap_uint<N>, where N can be 8, 16, 32, or 64
• short, unsigned short, int, unsigned int, long long, unsigned long long, and float
• std::complex<T>, where T can be int, short, or float

The following array RTP data types are supported:

• Arrays of ap_int<N> and ap_uint<N>, where N can be 8, 16, 32, or 64
• Arrays of short, unsigned short, int, unsigned int, long long, unsigned long long, or float
• Arrays of std::complex<T>, where T can be int, short, or float

When ap_int<N> and ap_uint<N> are used as RTPs, the PS program can use adf::graph::update and adf::graph::read with compatible data types to access RTPs. For example, use adf::graph::update(input_port& rtpPort, int32 value) to update the ap_int<32> run-time parameter. For more information on the use of RTPs, see Run-Time Graph Control API.

The only supported HLS function return type is void.

graph::update for an HLS scalar RTP greater than 32 bits should be called before graph::run.

To support the HLS math library inside the kernel, an additional linker option is needed for the AI Engine compiler:

--Xpslinker="-lhlsmc++-GCC46
-lIp_floating_point_v7_0_bitacc_cmodel 
-lIp_xfft_v9_1_bitacc_cmodel 
-lIp_fir_compiler_v7_2_bitacc_cmodel 
-lIp_dds_compiler_v6_0_bitacc_cmodel 
-L$(XILINX_HLS)/lnx64/tools/fpo_v7_0 
-L$(XILINX_HLS)/lnx64/lib/csim 
-L$(XILINX_HLS)/lnx64/tools/dds_v6_0 
-L$(XILINX_HLS)/lnx64/tools/fir_v7_0 
-L$(XILINX_HLS)/lnx64/tools/fft_v9_1 
-Wl,-rpath,$(XILINX_HLS)/lnx64/lib/csim 
-Wl,-rpath,$(XILINX_HLS)/lnx64/tools/fpo_v7_0 
-Wl,-rpath,$(XILINX_HLS)/lnx64/tools/fft_v9_1 
-Wl,-rpath,$(XILINX_HLS)/lnx64/tools/fir_v7_0 
-Wl,-rpath,$(XILINX_HLS)/lnx64/tools/dds_v6_0"