Developer Reference for Intel® Integrated Performance Primitives 2018

DFTFwd_CToC

Computes the forward discrete Fourier transform of a complex signal.

Syntax

Case 1: Operation on real data type

IppStatus ippsDFTFwd_CToC_32f(const Ipp32f* pSrcRe, const Ipp32f* pSrcIm, Ipp32f* pDstRe, Ipp32f* pDstIm, const IppsDFTSpec_C_32f* pDFTSpec, Ipp8u* pBuffer);

IppStatus ippsDFTFwd_CToC_64f(const Ipp64f* pSrcRe, const Ipp64f* pSrcIm, Ipp64f* pDstRe, Ipp64f* pDstIm, const IppsDFTSpec_C_64f* pDFTSpec, Ipp8u* pBuffer);

Case 2: Operation on complex data type

IppStatus ippsDFTFwd_CToC_32fc(const Ipp32fc* pSrc, Ipp32fc* pDst, const IppsDFTSpec_C_32fc* pDFTSpec, Ipp8u* pBuffer);

IppStatus ippsDFTFwd_CToC_64fc(const Ipp64fc* pSrc, Ipp64fc* pDst, const IppsDFTSpec_C_64fc* pDFTSpec, Ipp8u* pBuffer);

Include Files

ipps.h

Domain Dependencies

Flavors declared in ipps.h:

Headers: ippcore.h, ippvm.h

Libraries: ippcore.lib, ippvm.lib

Parameters

pDFTSpec

Pointer to the DFT specification structure.

pSrc

Pointer to the input array containing complex values.

pDst

Pointer to the output array containing complex values.

pSrcRe

Pointer to the input array containing real parts of the signal.

pSrcIm

Pointer to the input array containing imaginary parts of the signal.

pDstRe

Pointer to the output array containing real parts of the signal.

pDstIm

Pointer to the output array containing imaginary parts of the signal.

pBuffer

Pointer to the work buffer.

Description

These functions compute the forward DFT according to the pDFTSpec specification parameters: the transform len, the normalization flag, and the specific code hint.

The functions operating on the complex data type process the input complex array pSrc and store the result in pDst.

The functions operating on the real data type (processing complex signals represented by separate real pSrcRe and imaginary pSrcIm parts) store the result separately in pDstRe and pDstIm, respectively.

The function can be used with the external work buffer pBuffer2) Data vectors for these functions must be aligned to an appropriate number of bytes that is determined by the SIMD width that is supported by the customer's platform - it is reccomended to use ippMalloc function for such purpose as it guarantees such alignment.

Required buffer size must be computed by the corresponding function ippsDFTGet BufSize_C prior to using DFT computation functions. If a null pointer is passed, memory will be allocated by the DFT computation functions internally.

Note

Data vectors for these functions must be aligned to an appropriate number of bytes that is determined by the SIMD width that is supported by the customer's platform - use ippMalloc function for such alignment.

The forward DFT functionality can be described as follows:



where k is the index of elements in the frequency domain, n is the index of elements in the time domain, N is the input signal len, and A is a multiplier defined by flag. Also, x(n) is pSrc[n] and X(k) is pDst[k].

Optimization Notice

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804

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 pDFTSpec is incorrect.

ippStsMemAllocErr

Indicates an error when no memory is allocated.

ippStsFftFlagErr

Indicates an error when the flag value is incorrect.