end of ComplexFFTF32 group
◆ arm_cfft_init_1024_q31()
Initialization function for the cfft q31 function for 1024 samples.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_const_structs.h
◆ arm_cfft_init_128_q31()
Initialization function for the cfft q31 function for 128 samples.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_const_structs.h
◆ arm_cfft_init_16_q31()
Initialization function for the cfft q31 function for 16 samples.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_const_structs.h
◆ arm_cfft_init_2048_q31()
Initialization function for the cfft q31 function for 2048 samples.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_const_structs.h
◆ arm_cfft_init_256_q31()
Initialization function for the cfft q31 function for 256 samples.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_const_structs.h
◆ arm_cfft_init_32_q31()
Initialization function for the cfft q31 function for 32 samples.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_const_structs.h
◆ arm_cfft_init_4096_q31()
Initialization function for the cfft q31 function for 4096 samples.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_const_structs.h
◆ arm_cfft_init_512_q31()
Initialization function for the cfft q31 function for 512 samples.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_const_structs.h
◆ arm_cfft_init_64_q31()
Initialization function for the cfft q31 function for 64 samples.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_const_structs.h
◆ arm_cfft_init_dynamic_q31()
Initialize data structure for a FFT.
- Parameters
-
- Returns
- Pointer to the new structure
- This function is only available for Neon
- This function is allocating memory. The memory must be released when no more used. This function can be used with FFT lengths longer than the ones supported on Cortex-M
With this function, FFT lengths can also contain factor 3 and 5 (but must be multiple of 4)
◆ arm_cfft_init_q31()
Generic initialization function for the cfft q31 function.
- Parameters
-
| [in,out] | S | points to an instance of the floating-point CFFT structure |
| [in] | fftLen | fft length (number of complex samples) |
- Returns
- execution status
- Use of this function is mandatory only for the Helium and Neon versions of the FFT.
- Other versions can still initialize directly the data structure using variables declared in arm_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 CMSIS-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.
◆ arm_cfft_q31()
Processing function for the Q31 complex FFT.
- Parameters
-
| [in] | S | points to an instance of the fixed-point CFFT structure |
| [in,out] | p1 | points to the complex data buffer of size 2*fftLen. Processing occurs in-place |
| [in] | ifftFlag | flag that selects transform direction
- value = 0: forward transform
- value = 1: inverse transform
|
| [in] | bitReverseFlag | flag that enables / disables bit reversal of output
- value = 0: disables bit reversal of output
- value = 1: enables bit reversal of output
|
- Input and Output formats for CFFT Q31
| CFFT Size | Input Format | Output Format | Number of bits to upscale |
| 16 | 1.31 | 5.27 | 4 |
| 64 | 1.31 | 7.25 | 6 |
| 256 | 1.31 | 9.23 | 8 |
| 1024 | 1.31 | 11.21 | 10 |
- Input and Output formats for CIFFT Q31
| CIFFT Size | Input Format | Output Format | Number of bits to upscale |
| 16 | 1.31 | 5.27 | 0 |
| 64 | 1.31 | 7.25 | 0 |
| 256 | 1.31 | 9.23 | 0 |
| 1024 | 1.31 | 11.21 | 0 |
- Neon version
- The neon version has a different API. The input and output buffers must be different. There is a temporary buffer. The temporary buffer has same size as input or output buffer. The bit reverse flag is not more available in Neon version.
