Computes the inverse fast Fourier transform (FFT) of a real signal.
Case 1: Not-in-place operation on input data in Pack format
IppStatus ippsFFTInv_PackToR_32f(const Ipp32f* pSrc, Ipp32f* pDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PackToR_64f(const Ipp64f* pSrc, Ipp64f* pDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PackToR_16s_Sfs(const Ipp16s* pSrc, Ipp16s* pDst, const IppsFFTSpec_R_16s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PackToR_32s_Sfs(const Ipp32s* pSrc, Ipp32s* pDst, const IppsFFTSpec_R_32s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
Case 2: In-place operation on input data in Pack format
IppStatus ippsFFTInv_PackToR_32f_I(Ipp32f* pSrcDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PackToR_64f_I(Ipp64f* pSrcDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PackToR_16s_ISfs(Ipp16s* pSrcDst, const IppsFFTSpec_R_16s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PackToR_32s_ISfs(Ipp32s* pSrcDst, const IppsFFTSpec_R_32s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
Case 3: Not-in-place operation on input data in Perm format
IppStatus ippsFFTInv_PermToR_32f(const Ipp32f* pSrc, Ipp32f* pDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PermToR_64f(const Ipp64f* pSrc, Ipp64f* pDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PermToR_16s_Sfs(const Ipp16s* pSrc, Ipp16s* pDst, const IppsFFTSpec_R_16s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PermToR_32s_Sfs(const Ipp32s* pSrc, Ipp32s* pDst, const IppsFFTSpec_R_32s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
Case 4: In-place operation on input data in Perm format
IppStatus ippsFFTInv_PermToR_32f_I(Ipp32f* pSrcDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PermToR_64f_I(Ipp64f* pSrcDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PermToR_16s_ISfs(Ipp16s* pSrcDst, const IppsFFTSpec_R_16s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
IppStatus ippsFFTInv_PermToR_32s_ISfs(Ipp16s* pSrcDst, const IppsFFTSpec_R_32s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
Case 5 Not-in-place operation on input data in CCS format
IppStatus ippsFFTInv_CCSToR_32f(const Ipp32f* pSrc, Ipp32f* pDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_CCSToR_64f(const Ipp64f* pSrc, Ipp64f* pDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_CCSToR_16s_Sfs(const Ipp16s* pSrc, Ipp16s* pDst, const IppsFFTSpec_R_16s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
IppStatus ippsFFTInv_CCSToR_32s_Sfs(const Ipp32s* pSrc, Ipp32s* pDst, const IppsFFTSpec_R_32s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
IppStatus ippsFFTInv_CCSToR_32s16s_Sfs(const Ipp32s* pSrc, Ipp16s* pDst, const IppsFFTSpec_R_16s32s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
Case 6: In-place operation on input data in CCS format
IppStatus ippsFFTInv_CCSToR_32f_I(Ipp32f* pSrcDst, const IppsFFTSpec_R_32f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_CCSToR_64f_I(Ipp64f* pSrcDst, const IppsFFTSpec_R_64f* pFFTSpec, Ipp8u* pBuffer);
IppStatus ippsFFTInv_CCSToR_16s_ISfs(Ipp16s* pSrcDst, const IppsFFTSpec_R_16s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
IppStatus ippsFFTInv_CCSToR_32s_ISfs(Ipp32s* pSrcDst, const IppsFFTSpec_R_32s* pFFTSpec, int scaleFactor, Ipp8u* pBuffer);
pFFTSpec |
Pointer to the FFT specification structure. |
pSrc |
Pointer to the input array. |
pDst |
Pointer to the output array containing real values. |
pSrcDst |
Pointer to the input and output for the in-place operation. |
pBuffer |
Pointer to the external work buffer, can be NULL. |
scaleFactor |
Scale factor, refer to Integer Scaling. |
The functions ippsFFTInv_PermToR, ippsFFTInv_PackToR, and ippsFFTInv_CCSToR are declared in the ipps.h file. They compute the inverse FFT of data stored 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 the functions ippsFFTInitAlloc_R or ippsFFTInit_R. The length of the FFT must be a power of 2.
For integer data types the output result is scaled according to the scaleFactor value, thus the output signal range and precision are retained.
The function may be used with the external work buffer pBuffer to 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 function ippsFFTGetBufSize_R or ippsFFTGetSize_R.
If the external buffer is not specified (pBuffer is set to NULL), then the function itself allocates the memory needed for operation.
ippsFFTInv_PackToR. This function computes the inverse FFT of input data in Pack format.
ippsFFTInv_PermToR. This function computes the inverse FFT of input data in Perm format.
ippsFFTInv_CCSToR. This function computes the inverse FFT of input data in CCS format.
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. |
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