Re: [fpc-devel] The "magic div" algorithm

[Marģers . via fpc-devel]

I was over exited of making working example for byte div case. For word case it can be done.
In case of dword div it's not so nice. It's theoretically possible to shave 1 cpu clock cycle. And i have no working example jet. Sorry, for spreading false hope.

example for byte case:

function teByteDivBy7( divided : dword):dword; assembler; nostackframe;
asm
     mov ecx,divided
     mov eax,293
     mul ecx
     shr eax, 11
end;


 

----- Reply to message -----
Subject: Re: [fpc-devel] The "magic div" algorithm
From: Marģers . via fpc-devel <fpc-devel@lists.freepascal.org>
To: FPC developers' list <fpc-devel@lists.freepascal.org>

For unsigned byte, word and dword divisions by constant on 64 bit cpu can be converted as good cases.

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