ccfftip

Perform in-place fast Fourier transform.

The function interface declaration is as follows:

Initialization:
vsip_fft_f *vsip_ccfftip_create_f(uint32_t N, float scale, vsip_fft_dir dir, uint32_t ntimes, vsip_alg_hint hint);
Main function:
void vsip_ccfftip_f(const vsip_fft_f *Offt, const vsip_cvview_f *x);
Memory release:
int32_t vsip_fft_destroy_f(vsip_fft_f *fft);

Parameters

Parameter	Description	Value Range	Input/Output
N	Vector length	(1,∞)	Input
scale	Scaling coefficient after fast Fourier transform is complete.	Any real number	Input
dir	Direction of fast Fourier transform	Enumerated values of vsip_fft_dir: VSIP_FFT_FWD = -1: Forward VSIP_FFT_INV = +1: Inverse	Input
ntimes	Number of times that fast Fourier transform is performed. This parameter is invalid.	Any	Input
hint	Algorithm used in fast Fourier transform. This parameter is invalid.	Enumerated values of vsip_alg_hint: VSIP_ALG_SPACE = 0: Memory space VSIP_ALG_TIME = 1: Time consumption VSIP_ALG_NOISE = 2: Noise	Input
Offt/fft	Pointer to the fast Fourier transform structure	The value cannot be NULL.	Input
x	Pointer to the source vector	The value cannot be NULL.	Input/Output

Abnormal Input

When a null pointer is input, the function directly returns a result.

Note

Before this interface is called for calculation, the create function must be called to initialize the vsip_fft_f standard structure.
The initialization of the vsip_fft_f structure needs to be applied for in the create function. You cannot apply for and define this structure by yourself.
After the vsip_fft_f structure has been initialized, if a main function fails to be executed, the destroy function must be used to release the structure.

Example

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "kvsip.h"
#include "vsip.h"
#include "vsip_type.h"

#define BUFFER_SIZE_T 10
void CcfftipExample()
{
    float src[BUFFER_SIZE_T] = {1.64f, 1.63f, -1.09f, 0.71f, -3.20f, -0.43f, 0.41f, -4.83f, 5.36f, -4.40f};
    float dst[BUFFER_SIZE_T] = {1.64f, 1.63f, -1.09f, 0.71f, -3.20f, -0.43f, 0.41f, -4.83f, 5.36f, -4.40f};
    int64_t stride = 1;
    int64_t cvLen = BUFFER_SIZE_T / 2;
    uint64_t offset = 0;

    vsip_cblock_f *block_r = vsip_cblockbind_f(dst, NULL, cvLen, VSIP_MEM_NONE);
    vsip_cvview_f *r = vsip_cvbind_f(block_r, offset, stride, cvLen);
    vsip_cblockadmit_f(block_r, VSIP_TRUE);

    vsip_fft_f *Offt = vsip_ccfftip_create_f(cvLen, 1.0f, VSIP_FFT_FWD, 0, VSIP_ALG_SPACE);
    vsip_ccfftip_f(Offt, r);
    (void)vsip_fft_destroy_f(Offt);

    vsip_cvalldestroy_f(r);

    printf("src before:\n");
    for (int32_t i = 0; i < cvLen; ++i) {
        printf("%.2f ", src[i * 2]);
        printf("%.2f    ", src[i * 2 + 1]);
    }
    printf("\nsrc after:\n");
    for (int32_t i = 0; i < cvLen; ++i) {
        printf("%.2f ", dst[i * 2]);
        printf("%.2f    ", dst[i * 2 + 1]);
    }
    printf("\n");
}

int main(void) {
    CcfftipExample();
    return 0;
}

Output:

src before:
1.64 1.63    -1.09 0.71    -3.20 -0.43    0.41 -4.83    5.36 -4.40
src after:
3.12 -7.32    12.66 13.00    -3.86 3.35    -1.50 2.63    -2.23 -3.51

Parent topic: Fast Fourier Operation Functions