Intel® Integrated Performance Primitives Developer Reference

Developer Reference

  • 2020
  • 07/15/2020
  • Public Content
Contents

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
pBuffer
2) 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.
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.

Product and Performance Information

1

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