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CMSIS DSP RFFT - too much cycles

Knut H

Hi,

I use the CMSIS DSP library to calculate a f32 RFFT with a block size of 1024. For this it takes 262823 cycles. I read in the white-paper that it should take 55538 cycles. Because of the measurement is too slow, i have to speed it up. What could be the reason of the too much cycles?

Thanks

My setup:
Cortex-M4 on a TI-MSP432
TI-Code Composer Studio
wait states = 0
function: arm_rfft_fast_f32()

white-paper: community.arm.com/.../7563.ARM-white-paper-_2D00_-DSP-capabilities-of-Cortex_2D00_M4-and-Cortex_2D00_M7.pdf

Parents
  • 0 in reply to Westonsupermare Pier

    Hi,

    email the notification ended in my spam folder...

    - Yes the building has FPU enabled.
    - Optimization settings: At first I used the default setting, then I set it to full speed setup. The difference was marginally.
    - Yes, I think that I compare like with like. I calculate a RFFT F32 with block size 1024 on a Cortex-M4 without wait states.

    What else could cause be the difference?

    Thanks

Reply
  • 0 in reply to Westonsupermare Pier

    Hi,

    email the notification ended in my spam folder...

    - Yes the building has FPU enabled.
    - Optimization settings: At first I used the default setting, then I set it to full speed setup. The difference was marginally.
    - Yes, I think that I compare like with like. I calculate a RFFT F32 with block size 1024 on a Cortex-M4 without wait states.

    What else could cause be the difference?

    Thanks

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