DFTInit_R, DFTInit

Initializes the DFT specification structure for real and complex signals.

Syntax

Case 1: Operation on real signal

IppStatus ippsDFTInit_R_32f(int length, int flag, IppHintAlgorithm hint, IppsDFTSpec_R_32f* pDFTSpec, Ipp8u* pMemInit);

IppStatus ippsDFTInit_R_64f(int length, int flag, IppHintAlgorithm hint, IppsDFTSpec_R_64f* pDFTSpec, Ipp8u* pMemInit);

Case 2: Operation on complex signal

IppStatus ippsDFTInit_C_32fc(int length, int flag, IppHintAlgorithm hint, IppsDFTSpec_C_32fc* pDFTSpec, Ipp8u* pMemInit);

IppStatus ippsDFTInit_C_32f(int length, int flag, IppHintAlgorithm hint, IppsDFTSpec_C_32f* pDFTSpec, Ipp8u* pMemInit);

IppStatus ippsDFTInit_C_64fc(int length, int flag, IppHintAlgorithm hint, IppsDFTSpec_C_64fc* pDFTSpec, Ipp8u* pMemInit);

IppStatus ippsDFTInit_C_64f(int length, int flag, IppHintAlgorithm hint, IppsDFTSpec_C_64f* pDFTSpec, Ipp8u* pMemInit);

Include Files

ipps.h

Domain Dependencies

Headers: ippcore.h, ippvm.h

Libraries: ippcore.lib, ippvm.lib

Parameters

length	Length of the DFT transform.
flag	Specifies the result normalization method. The values for the flag argument are described in the section Flag and Hint Arguments.
hint	This parameter is deprecated. Set the value to ippAlgHintNone.
pDFTSpec	Pointer to the DFT specification structure to be initialized.
pMemInit	Pointer to the temporary work buffer.

Description

These functions initialize the DFT specification structure pDFTSpec with the following parameters: the transform length, the normalization flag, and the specific code hint. The length argument defines the transform length.

Before calling these functions the memory must be allocated for the DFT specification structure and the temporary work buffer (if it is required). The size of the DFT specification structure and the work buffer must be computed by the functions ippsDFTGetSize_R or ippsDFTGetSize_C.

If the work buffer is not used, the parameter pMemInit can be NULL. If the work buffer is used, the parameter pMemInit cannot be NULL. After initialization is done, the temporary work buffer can be freed.

ippsDFTInit_R function initializes the real DFT specification structure.

ippsDFTInit_C function initializes the complex DFT specification structure.

Application Notes

The maximum values for length are:

Function Flavor	Max length
C_32fc	134217727 (2^27 - 1)
C_64fc	67108863 (2^26 - 1)

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when one of the specified pointers is NULL.
ippStsFftFlagErr	Indicates an error when the flag value is incorrect.
ippStsFftOrderErr	Indicates an error when the memory needed to calculate the length value of the DFT transform exceeds the limit.
ippStsSizeErr	Indicates an error when length is less than, or equal to 0.