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Subject: Re: Speaking of fast ways to do things...

Author: Andrew Dados

Date: 11:28:33 04/19/00

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On April 19, 2000 at 13:49:25, Dann Corbit wrote:

>What is the fastest way to fill a linear array of bytes with zero, given the
>following conditions:
>1.  Intel PII or higher CPU
>2.  Guarantee that the number of bytes is an even number?
>
>I am porting a chess program, and memset() is the bottleneck.  I don't need to
>memset an arbitrary character.  It's always zero.

for pure 32bit windoze (assuming es==ds):

asm
 mov edi, begin_address
 mov ecx, count ; number of words to fill
 xor eax,eax    ; filling with 0x0000
 shr ecx,2      ; here carry gets set if count is not divisible by 4
 rep stosd
 jnc @finito
 stosw          ; fill extra word if count mod 4 !=0
@finito:
end;

• Re: Speaking of fast ways to do things... Andrew Dados 11:33:38 04/19/00
  • Re: Speaking of fast ways to do things... Dann Corbit 11:54:34 04/19/00
    • Re: Speaking of fast ways to do things... Michel Langeveld 12:23:54 04/19/00
      • Re: Speaking of fast ways to do things... Dann Corbit 12:33:14 04/19/00
        • Re: Speaking of fast ways to do things... Bruce Moreland 18:45:27 04/20/00
        • Re: Speaking of fast ways to do things... Heiner Marxen 17:01:11 04/19/00
          • Re: Speaking of fast ways to do things... Bo Persson 05:41:44 04/21/00

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