NMSIS-DSP  Version 1.3.1
NMSIS DSP Software Library
Macros | Functions
Complex FFT Q31
Transform Functions » Complex FFT Functions

Macros

#define FFTINIT(EXT, SIZE)
 
#define CFFTINIT_Q31(LEN, LENTWIDDLE)
 

Functions

RISCV_DSP_ATTRIBUTE riscv_status riscv_cfft_init_q31 (riscv_cfft_instance_q31 *S, uint16_t fftLen)
 Initialization function for the cfft q31 function for 4096 samples. More...
 
RISCV_DSP_ATTRIBUTE void riscv_cfft_q31 (const riscv_cfft_instance_q31 *S, q31_t *p1, uint8_t ifftFlag, uint8_t bitReverseFlag)
 Processing function for the Q31 complex FFT. More...
 

Detailed Description

Macro Definition Documentation

◆ CFFTINIT_Q31

#define CFFTINIT_Q31 (   LEN,
  LENTWIDDLE 
)

◆ FFTINIT

#define FFTINIT (   EXT,
  SIZE 
)

Function Documentation

◆ riscv_cfft_init_q31()

RISCV_DSP_ATTRIBUTE riscv_status riscv_cfft_init_q31 ( riscv_cfft_instance_q31 *  S,
uint16_t  fftLen 
)

Initialization function for the cfft q31 function for 4096 samples.

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h

Initialization function for the cfft q31 function for 2048 samples

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h

Initialization function for the cfft q31 function for 1024 samples

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h

Initialization function for the cfft q31 function for 512 samples

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h

Initialization function for the cfft q31 function for 256 samples

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h

Initialization function for the cfft q31 function for 128 samples

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h

Initialization function for the cfft q31 function for 64 samples

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h

Initialization function for the cfft q31 function for 32 samples

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h

Initialization function for the cfft q31 function for 16 samples

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h

Generic initialization function for the cfft q31 function

Parameters
[in,out]Spoints to an instance of the floating-point CFFT structure
[in]fftLenfft length (number of complex samples)
Returns
execution status
Use of this function is mandatory only for the MVE version of the FFT.
Other versions can still initialize directly the data structure using variables declared in riscv_const_structs.h
This function should be used only if you don't know the FFT sizes that you'll need at build time. The use of this function will prevent the linker from removing the FFT tables that are not needed and the library code size will be bigger than needed.
If you use NMSIS-DSP as a static library, and if you know the FFT sizes that you need at build time, then it is better to use the initialization functions defined for each FFT size.

◆ riscv_cfft_q31()

RISCV_DSP_ATTRIBUTE void riscv_cfft_q31 ( const riscv_cfft_instance_q31 *  S,
q31_t *  p1,
uint8_t  ifftFlag,
uint8_t  bitReverseFlag 
)

Processing function for the Q31 complex FFT.

Parameters
[in]Spoints to an instance of the fixed-point CFFT structure
[in,out]p1points to the complex data buffer of size 2*fftLen. Processing occurs in-place
[in]ifftFlagflag that selects transform direction
  • value = 0: forward transform
  • value = 1: inverse transform
[in]bitReverseFlagflag that enables / disables bit reversal of output
  • value = 0: disables bit reversal of output
  • value = 1: enables bit reversal of output