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Horizon Smart Car Developer Community
Horizon Official Website
Guide
Horizon Smart Car Developer Community
Horizon Official Website
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Inverse Fast Fourier Transform

Inverse Fast Fourier Transform (hereinafter referred to as IFFT) is a fast algorithm of Inverse Discrete Fourier Transform (hereinafter referred to as IDFT). It is one of the most basic methods in time domain and frequency domain transform analysis. The algorithm enables interconversion of data from frequency domain to time domain.

Operator Effect

Time Domain Input DataParameterFrequency Domain Output Data
imagep_size = HB_HPL_FFT16
normalize = 0
dataType = HB_HPL_DATA_TYPE_I16
imFormat = HB_IM_FORMAT_SEPARATE
numDimensionSize = 1		image

Principle

Please refer to the section FFT section principle.

API Interface

int32_t hbIFFT1D(hbUCPTaskHandle_t *taskHandle, hbHPLImaginaryData *dst, hbHPLImaginaryData const *src, hbHPLIFFTParam const *param);

For detailed interface information, please refer to hbIFFT1D.

Usage

// Include the header #include "hobot/hb_ucp.h" #include "hobot/hpl/hb_hpl.h" #include "hobot/hpl/hb_ifft.h" // init, allocate memory for data src_length = 1024 * 1024 * 5; hbUCPMallocCached(&src_re_mem, src_length, 0); hbUCPMallocCached(&src_im_mem, src_length, 0); hbHPLImaginaryData src; src.realDataVirAddr = src_re_mem.virAddr; src.realDataPhyAddr = src_re_mem.phyAddr; src.imDataVirAddr = src_im_mem.virAddr; src.imDataPhyAddr = src_im_mem.phyAddr; src.numDimensionSize = 1; src.dataType = HB_HPL_DATA_TYPE_I16; src.imFormat = HB_IM_FORMAT_SEPARATE; src.dimensionSize[0] = 16 * 11; hbUCPMallocCached(&dst_re_mem, src_length, 0); hbUCPMallocCached(&dst_im_mem, src_length, 0); hbHPLImaginaryData dst; dst.realDataVirAddr = dst_re_mem.virAddr; dst.realDataPhyAddr = dst_re_mem.phyAddr; dst.imDataVirAddr = dst_im_mem.virAddr; dst.imDataPhyAddr = dst_im_mem.phyAddr; dst.numDimensionSize = 1; dst.dataType = HB_HPL_DATA_TYPE_I16; dst.imFormat = HB_IM_FORMAT_SEPARATE; dst.dimensionSize[0] = 16 * 11; // init param hbIFFTParam param; param.pSize = HB_FFT_POINT_SIZE_16; param.normalize = 0; // init task handle and schedule param hbUCPTaskHandle_t task_handle{nullptr}; hbUCPSchedParam sched_param; HB_UCP_INITIALIZE_SCHED_PARAM(&sched_param); sched_param.backend = HB_UCP_DSP_CORE_0; // create task hbIFFT1D(&task_handle, &dst, &src, &param); // submit task hbUCPSubmitTask(task_handle, &sched_param); // wait for task done hbUCPWaitTaskDone(task_handle, 0); // release task handle hbUCPReleaseTask(task_handle); // release memory hbUCPFree(&src_re_mem); hbUCPFree(&src_im_mem); hbUCPFree(&dst_re_mem); hbUCPFree(&dst_im_mem);