Intel® Integrated Performance Primitives Developer Reference

Developer Reference

  • 2021
  • 01/25/2021
  • Public Content
Contents

FFTInit_R
,
FFTInit_C

Initializes the FFT specification structure for real and complex signals.

Syntax

Case 1: Operation on real signal
IppStatus ippsFFTInit_R_32f(IppsFFTSpec_R_32f**
ppFFTSpec
, int
order
, int
flag
, IppHintAlgorithm
hint
, Ipp8u*
pSpec
, Ipp8u*
pSpecBuffer
);
IppStatus ippsFFTInit_R_64f(IppsFFTSpec_R_64f**
ppFFTSpec
, int
order
, int
flag
, IppHintAlgorithm
hint
, Ipp8u*
pSpec
, Ipp8u*
pSpecBuffer
);
Case 2: Operation on complex signal
IppStatus ippsFFTInit_C_32f(IppsFFTSpec_C_32f**
ppFFTSpec
, int
order
, int
flag
, IppHintAlgorithm
hint
, Ipp8u*
pSpec
, Ipp8u*
pSpecBuffer
);
IppStatus ippsFFTInit_C_64f(IppsFFTSpec_C_64f**
ppFFTSpec
, int
order
, int
flag
, IppHintAlgorithm
hint
, Ipp8u*
pSpec
, Ipp8u*
pSpecBuffer
);
IppStatus ippsFFTInit_C_32fc(IppsFFTSpec_C_32fc**
ppFFTSpec
, int
order
, int
flag
, IppHintAlgorithm
hint
, Ipp8u*
pSpec
, Ipp8u*
pSpecBuffer
);
IppStatus ippsFFTInit_C_64fc(IppsFFTSpec_C_64fc**
ppFFTSpec
, int
order
, int
flag
, IppHintAlgorithm
hint
, Ipp8u*
pSpec
, Ipp8u*
pSpecBuffer
);
Include Files
ipps.h
Domain Dependencies
Headers:
ippcore.h
,
ippvm.h
Libraries:
ippcore.lib
,
ippvm.lib
Parameters
order
FFT order. The input signal length is
N
= 2
order
.
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
.
ppFFTSpec
Double pointer to the FFT specification structure to be created.
pSpec
Pointer to the area for the FFT specification structure.
pSpecBuffer
Pointer to the work buffer.
Description
These functions initialize the FFT specification structure
ppFFTSpec
 with the following parameters:
  • the transform
    order
    . This parameter defines the transform length. Input and output signals are arrays of 2
    order
     length.
  • the normalization
    flag
  • the specific code
    hint
Before calling these functions, you need to compute the size of the specification structure and the work buffer (if it is required) using the
ippsFFTGetSize_R
 and
ippsFFTGetSize_C
 functions.
If
pSpecBufferSize
 returned by the
ippsFFTGetSize
 function is equal to zero, the parameter
pSpecBuffer
 can be
NULL
.
The suffix after the function name indicates the flavors of the FFT functions:
ippsFFTInit_C
 is for complex flavors and
ippsFFTInit_R
 is for real flavors.
Application Notes
The maximum values for signal length are:
Function Flavor
Max Length
C_32fc
268435456 (2^28)
C_64fc
67108864 (2^27)
Return Values
ippStsNoErr
Indicates no error.
ippStsNullPtrErr
Indicates an error when one of the specified pointers is
NULL
.
ippStsFftOrderErr
Indicates an error when the
order
 value is incorrect.
ippStsFftFlagErr
Indicates an error when the
flag
 value is incorrect.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.