Date:	Wed, 19 Jun 2002 18:42:39 +0300 (WET)
From:	Andris Pavenis <pavenis AT lanet DOT lv>
X-Sender:	pavenis AT ieva06
To:	billy chen <billyc AT intrex DOT net>
Cc:	djgpp AT delorie DOT com
Subject:	Re: Need help for rdtsc inline asm
In-Reply-To:	<ugv5asq8muh79d@corp.supernews.com>
Message-ID:	<Pine.A41.4.05.10206191836300.27608-100000@ieva06>
MIME-Version:	1.0
Reply-To:	djgpp AT delorie DOT com
Errors-To:	nobody AT delorie DOT com
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On Tue, 18 Jun 2002, billy chen wrote:

> Hi everyone,
> 
> I try to write an inline asm code for getting the time stamp counter a 64
> bits will store at edx:eax when rdtsc is called. Hoever I could not get to
> working by passing the compiler not allow the compiler (gcc 2.95.2 (djgpp
> 2.03))  to follow the asm code for me, even I am using asm volatile   and
> looks like the gas did not know how to translate the rdtsc code to machine ?
> Could some one help on this ?

Which version of binutils do You have? Any reasonable resent binutils
version understands rdtsc instruction. Anyway You can write something
like:

inline long long rdtsc(void)
{
     union { long L[2]; long long LL; } W;
     asm __volatile__ (".byte 0x0F,0x31" : "=a"(W.L[0]), "=d"(W.L[1]));
     return W.LL;
}

(I have more nicer example somewhere, but I don't want to search now
Also this should work).

But make sure You are running CPU which supports RDTSC, or You'll get 
SIGILL

Andris

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