Developer Reference

  • 2020
  • 07/15/2020
  • 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

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