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Lingjun Kong
Lingjun Kong
Associate III
Aug 3, 2017 8:11 PM UTC
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Question about the assemble code for floating point computing: the FPU didn't be used in fact?

Posted on August 03, 2017 at 22:11

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    Tesla DeLorean
    Tesla DeLoreanBest answer
    Guru
    Aug 3, 2017 8:50 PM UTC
    Posted on August 03, 2017 at 22:50

    Your CPU only has a single precision FPU, this is why it the double precision computations are being done in software, it is using the FPU registers as extra holding space.

    The FPU isn't inherently complicated, it only implements fairly basic math functionality which you can gleen from the opcode name. The cleverness with come from how you manage the register resources to minimize the movement in/out, and make the math flow. The FPU does not hold higher precision intermediate results.

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    Tesla DeLorean
    Tesla DeLoreanBest answer
    Guru
    Aug 3, 2017 8:50 PM UTC
    Posted on August 03, 2017 at 22:50

    Your CPU only has a single precision FPU, this is why it the double precision computations are being done in software, it is using the FPU registers as extra holding space.

    The FPU isn't inherently complicated, it only implements fairly basic math functionality which you can gleen from the opcode name. The cleverness with come from how you manage the register resources to minimize the movement in/out, and make the math flow. The FPU does not hold higher precision intermediate results.

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    Tesla DeLorean
    Tesla DeLorean
    Guru
    Aug 3, 2017 10:52 PM UTC
    Posted on August 03, 2017 at 22:52

    See FPU Check code in this thread

    https://community.st.com/0D50X00009XkYbhSAF

    https://community.st.com/0D50X00009XkYbhSAF#comment-151216

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