FFT Struct Parameters - 2021.2 English

Vitis High-Level Synthesis User Guide (UG1399)

Document ID
English (United States)
Release Date
2021.2 English
Table 1. FFT Struct Parameters
Parameter Description
input_width Data input port width.
output_width Data output port width.
status_width Output status port width.
config_width Input configuration port width.
max_nfft The size of the FFT data set is specified as 1 << max_nfft.
has_nfft Determines if the size of the FFT can be runtime configurable.
channels Number of channels.
arch_opt The implementation architecture.
phase_factor_width Configure the internal phase factor precision.
ordering_opt The output ordering mode.
ovflo Enable overflow mode.
scaling_opt Define the scaling options.
rounding_opt Define the rounding modes.
mem_data Specify using block or distributed RAM for data memory.
mem_phase_factors Specify using block or distributed RAM for phase factors memory.
mem_reorder Specify using block or distributed RAM for output reorder memory.
stages_block_ram Defines the number of block RAM stages used in the implementation.
mem_hybrid When block RAMs are specified for data, phase factor, or reorder buffer, mem_hybrid specifies where or not to use a hybrid of block and distributed RAMs to reduce block RAM count in certain configurations.
complex_mult_type Defines the types of multiplier to use for complex multiplications.
butterfly_type Defines the implementation used for the FFT butterfly.

When specifying parameter values which are not integer or boolean, the HLS FFT namespace should be used.

For example, the possible values for parameter butterfly_type in the following table are use_luts and use_xtremedsp_slices. The values used in the C program should be butterfly_type = hls::ip_fft::use_luts and butterfly_type = hls::ip_fft::use_xtremedsp_slices.