#18 Use MULXU.W in lib1funcs.asm:mulsi3 for H8S

Pavel Pisa

I was frightened, that lib1funcs.asm:mulsi3 uses
bit by bit loop for int32*int32 => int32 computation.
It significantly decreases speed of my algorithms.

This should be changed to three MULXU.W
at least for H8S. The instruction MULXU.W
takes 20 cycles on H8S/2000 and on H8S/2600
it takes 4 cycles. It is far faster then loop.
I am not sure about H8H. It can be no reason
to use MULXU.W on that platform.

If nobody is working on that, I can prepare
and send patch when I will have one spare hour.


  • Pavel Pisa

    Pavel Pisa - 2003-02-23

    Logged In: YES

    I have tried to reimplement division as well.
    I am not sure if my implementation would be faster on H8S/2000,
    I hope, that it is faster on 2600, but I have measured that yet.

    Please, revise the code, I need to be absolutely sure, that
    it is OK.

  • Kazu Hirata

    Kazu Hirata - 2003-11-13

    Logged In: YES

    Just committed to mainline.

  • Kazu Hirata

    Kazu Hirata - 2003-11-13
    • assigned_to: nobody --> kazuhirata
    • status: open --> closed

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