template class xf::dsp::aie::fft::dit_1ch::fft_ifft_dit_1ch_base_graph¶
#include "fft_ifft_dit_1ch_graph.hpp"
Overview¶
fft_dit_1ch is a single-channel, decimation-in-time, fixed point size FFT
These are the templates to configure the single-channel decimation-in-time class.
Parameters:
| TT_DATA | describes the type of individual data samples input to and output from the transform function. This is a typename and must be one of the following: int16, cint16, int32, cint32, float, cfloat. |
| TT_TWIDDLE | describes the type of twiddle factors of the transform. It must be one of the following: cint16, cint32, cfloat and must also satisfy the following rules:
|
| TP_POINT_SIZE | is an unsigned integer which describes the number of point size of the transform. This must be 2^N where N is an integer in the range 4 to 16 inclusive. When TP_DYN_PT_SIZE is set, TP_POINT_SIZE describes the maximum point size possible. |
| TP_FFT_NIFFT | selects whether the transform to perform is an FFT (1) or IFFT (0). |
| TP_SHIFT | selects the power of 2 to scale the result by prior to output. |
| TP_CASC_LEN | selects the number of kernels the FFT will be divided over in series to improve throughput |
| TP_DYN_PT_SIZE | selects whether (1) or not (0) to use run-time point size determination. When set, each frame of data must be preceeded, in the window, by a 256 bit header. The output frame will also be preceeded by a 256 bit vector which is a copy of the input vector, but for the top byte, which is 0 to indicate a legal frame or 1 to indicate an illegal frame. The lowest significance byte of the input header field describes forward (non-zero) or inverse(0) direction. The second least significant byte 8 bits of this field describe the Radix 2 power of the following frame. e.g. for a 512 point size, this field would hold 9, as 2^9 = 512. Any value below 4 or greater than log2(TP_POINT_SIZE) is considered illegal. When this occurs the top byte of the output header will be set to 1 and the output samples will be set to 0 for a frame of TP_POINT_SIZE |
| TP_WINDOW_VSIZE | is an unsigned intered which describes the number of samples in the input window. By default, TP_WINDOW_SIZE is set ot match TP_POINT_SIZE. TP_WINDOW_SIZE may be set to be an integer multiple of the TP_POINT_SIZE, in which case multiple FFT iterations will be performed on a given input window, resulting in multiple iterations of output samples, reducing the numer of times the kernel needs to be triggered to process a given number of input data samples. As a result, the overheads inferred during kernel triggering are reduced and overall performance is increased. This is the base class for the Single channel DIT FFT graph - one or many cascaded kernels for higher throughput |
template < typename TT_DATA, typename TT_TWIDDLE, unsigned int TP_POINT_SIZE, unsigned int TP_FFT_NIFFT, unsigned int TP_SHIFT, unsigned int TP_CASC_LEN = 1, unsigned int TP_DYN_PT_SIZE = 0, unsigned int TP_WINDOW_VSIZE = TP_POINT_SIZE > class fft_ifft_dit_1ch_base_graph: public graph // fields port <input> in port <output> out kernel m_fftKernels[TP_CASC_LEN] parameter fft_buf1 parameter fft_lut1 parameter fft_lut1a parameter fft_lut1b parameter fft_lut2 parameter fft_lut2a parameter fft_lut2b parameter fft_lut3 parameter fft_lut3a parameter fft_lut3b parameter fft_lut4 parameter fft_lut4a parameter fft_lut4b parameter fft_buf4096 parameter fft_buf2048 parameter fft_buf1024 parameter fft_buf512 parameter fft_buf256 parameter fft_buf128
Fields¶
port <input> in
The input data to the function. This input is a window API of samples of TT_DATA type. The number of samples in the window is described by TP_POINT_SIZE.
port <output> out
A window API of TP_POINT_SIZE samples of TT_DATA type.