ARM CMSIS-DSP arm_rfft_init_<len>_q15 for FFT initialisation

[bramble]

Hi,

I'm using the CMSIS-DSP library for FFT calculation, using build-time configurable FFT lengths in the range 64 - 1024. The CMSIS-DSP documentation recommends that, when the FFT length is known, using an appropriate initialisation function such as arm_rfft_init_512_q15() for a 512-length real FFT is preferred over the generic initialiser arm_rfft_init_q15(), since the former allows unused tables to be removed by the linker.

I can only find arm_rfft_init_q15() in the repository.

I'm using STM32Cube_FW_H7_V1.12.1 but I can't see how to determine which version of CMSIS-DSP that includes (having searched include files for a define, which I'm sure must be hidden there somewhere!).

Does anyone know whether those additional FFT init functions have been deliberately excluded from the H7's repository?

Advice about how to check the CMSIS-DSP version would also be appreciated.

Thanks in advance.

[AScha.3]

Hi,

just look on git.. CMSIS-DSP 1.16.2

https://github.com/ARM-software/CMSIS-DSP

-> arm_status arm_rfft_init_512_q15(arm_rfft_instance_q15 * S);

[bramble · Accepted solution]

I think I found the answer to my own questions. The CMSIS version distributed with H7 is defined as instructed here:

So it turns out that the DSP library is very old indeed, evidently the missing functions have been added at a later stage, the current version being 1.16.2.

This is worth noting for anyone using CMSIS-DSP - best not to rely on the H7 repository if you want the latest and greatest, since there will no doubt be bug fixes as well as enhancements in the latest version (as @AScha.3 , mentioned, available in github).

Thanks