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DSP instruction for x*x + y*y. Does it exist?

Matic

Hello all!

I am new to ARM community and this is my first question here. I work on embedded systems where we use Cortex-M4 based MCUs (concretely STM32F3 series). I would like to ask, if there is a DSP instruction which would calculate x*x + y*y.

x and y represent sine and cosine values (signed integers, 16-bit variables are sufficient). I would like to calculate a square of amplitude (x*x + y*y).

Thanks in advance.

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  • 0 in reply to Yasuhiko Koumoto

    Hi.

    Thank you a lot. I played a little bit with that and other similar instructions and it works quite well. I noticed that SMLALD has an "accumulate" feature, which I don't need. Actually, it is a drawback in my case, because I would have to clear that accumulator back to zero before each use of the instruction.

    Maybe SMLAD should be better, where I could multiply topHW * topHW + bottomHW * bottomHW, then add zero and write this to destination variable.

Reply
  • 0 in reply to Yasuhiko Koumoto

    Hi.

    Thank you a lot. I played a little bit with that and other similar instructions and it works quite well. I noticed that SMLALD has an "accumulate" feature, which I don't need. Actually, it is a drawback in my case, because I would have to clear that accumulator back to zero before each use of the instruction.

    Maybe SMLAD should be better, where I could multiply topHW * topHW + bottomHW * bottomHW, then add zero and write this to destination variable.

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