Developer Reference for Intel® Integrated Performance Primitives 2019

FFTFwd_RToPack, FFTFwd_RToPerm, FFTFwd_RToCCS

Computes the forward or inverse fast Fourier transform (FFT) of a real signal.

Syntax

Case 1: Not-in-place operation, result in Pack Format

IppStatus ippsFFTFwd_RToPack_32f(const Ipp32f* pSrc, Ipp32f* pDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);

IppStatus ippsFFTFwd_RToPack_64f(const Ipp64f* pSrc, Ipp64f* pDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);

Case 2: In-place operation, result in Pack Format.

IppStatus ippsFFTFwd_RToPack_32f_I(Ipp32f* pSrcDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);

IppStatus ippsFFTFwd_RToPack_64f_I(Ipp64f* pSrcDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);

Case 3: Not-in-place operation, result in Perm Format

IppStatus ippsFFTFwd_RToPerm_32f(const Ipp32f* pSrc, Ipp32f* pDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);

IppStatus ippsFFTFwd_RToPerm_64f(const Ipp64f* pSrc, Ipp64f* pDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);

Case 4: In-place operation, result in Perm Format.

IppStatus ippsFFTFwd_RToPerm_32f_I(Ipp32f* pSrcDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);

IppStatus ippsFFTFwd_RToPerm_64f_I(Ipp64f* pSrcDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);

Case 5: Not-in-place operation, result in CCS Format

IppStatus ippsFFTFwd_RToCCS_32f(const Ipp32f* pSrc, Ipp32f* pDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);

IppStatus ippsFFTFwd_RToCCS_64f(const Ipp64f* pSrc, Ipp64f* pDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);

Case 6: In-place operation, result in CCS Format.

IppStatus ippsFFTFwd_RToCCS_64f_I(Ipp64f* pSrcDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);

IppStatus ippsFFTFwd_RToCCS_32f_I(Ipp32f* pSrcDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);

Include Files

ipps.h

Domain Dependencies

Headers: ippcore.h, ippvm.h

Libraries: ippcore.lib, ippvm.lib

Parameters

pFFTSpec

Pointer to the FFT specification structure.

pSrc

Pointer to the input array.

pDst

Pointer to the output array containing packed complex values.

pSrcDst

Pointer to the input and output arrays for the in-place operation.

pBuffer

Pointer to the external work buffer.

Description

These functions compute the forward FFT of a real signal and store the result in Pack, Perm, or CCS packed formats respectively. The transform is performed in accordance with the pFFTSpec specification parameters: the transform order, the normalization flag, and the specific code hint. Before calling these functions the FFT specification structure must be initialized by the corresponding flavors of ippsFFTInit_R. The length of the FFT must be a power of 2.

The function may be used with the external work buffer pBufferto avoid memory allocation within the functions. Once the work buffer is allocated, it can be used for all following calls to the functions computing FFT. As internal allocation of memory is too expensive operation and depends on operating system and/or runtime libraries used - the use of an external buffer improves performance significantly, especially for the small size transforms.

The size of the external buffer must be previously computed by the ippsFFTGetSize_R function.

If the external buffer is not specified (pBuffer is set to NULL), then the function itself allocates the memory needed for operation.

ippsFFTFwd_RToPack. This function computes the forward FFT and stores the result in Pack format.

ippsFFTFwd_RToPerm. This function computes the forward FFT and stores the result in Perm format.

ippsFFTFwd_RToCCS. This function computes the forward FFT and stores the result in CCS format.

Tables "Arrangement of Forward Fourier Transform Results in Packed Formats - Even Length" and "Forward Fourier transform Result Representation in Packed Formats - Odd Length" show how the output results are arranged in the packed formats.

Return Values

ippStsNoErr

Indicates no error.

ippStsNullPtrErr

Indicates an error when one of the specified pointers with exception of pBuffer is NULL.

ippStsContextMatchErr

Indicates an error when the specification identifier pFFTSpec is incorrect.

ippStsMemAllocErr

Indicates an error when no memory is allocated.

Example

FFTFwd_RToCCS.c