Save some clocks ?

From: Andrew Kennedy (andrewkennedy2_at_LOGev1.net)
Date: 02/26/04

  • Next message: Andrew Kennedy: "Re: Where can I get tasm?" 
    Date: Thu, 26 Feb 2004 08:02:54 +0000 (UTC)

    Any comment on the comment near the bottom that someone gave me about the
    jmp + 2.

    xor eax, eax
    cpuid
    rdtsc
    mov edi, eax ; save lower 32 bits in edi
    xor eax, eax
    cpuid

    ; Insert timed code here

    xor eax, eax
    cpuid
    rdtsc
    sub edi, eax
    xor eax, eax
    sub eax, edi ; eax = result

    Joined: 19 May 2003
    Posts: 372
    Location: 8003F000
    PostPosted: 02-25-2004 07:44 PM Post subject: Reply with quote
    You don't have to use "cpuid" instruction.
    "jmp $+2" puts the CPU back into order too, and
    doesn't run 200 clocks, like "cpuid".

  • Next message: Andrew Kennedy: "Re: Where can I get tasm?"

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