Message-Id: <200005231133.NAA06460@cerbere.u-strasbg.fr>
X-Sender: muller AT ics DOT u-strasbg DOT fr
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Date: Tue, 23 May 2000 13:14:59 +0200
To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
From: Pierre Muller <muller AT cerbere DOT u-strasbg DOT fr>
Subject: Re: Simple C program showing FPU problem !
Cc: djgpp-workers AT delorie DOT com
References: <200005231107 DOT NAA06048 AT cerbere DOT u-strasbg DOT fr>
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Reply-To: djgpp-workers AT delorie DOT com

At 14:10 23/05/00 +0300, you wrote:
>
>On Tue, 23 May 2000, Pierre Muller wrote:
>
>>   	.global	___djgpp_npx_hdlr
>>   ___djgpp_npx_hdlr:
>>   	pushl	%eax
>> +    fnstsw ___djgpp_fpu_status
>> +    fnclex
>>   	xorl	%eax,%eax
>>   	outb	%al,$0x0f0
>>   	movb	$0x20,%al
>
>Shouldn't we access the I/O port *before* clearing the exceptions, like 
>Intel says?

  Maybe, I did not try the other way around !

>> ! 	xchgw   ___djgpp_fpu_status,%ax
>> ! 	movzwl  %ax, %eax
>> ! 	cmpl    %eax,%eax
>> ! 	jne     L__clear87_end
>>   	fstsw	%ax
>>   	movzwl	%ax, %eax
>>   	fclex
>> + L__clear87_end:
>
>Why do you avoid FCLEX if the status word is taken from the value saved 
>by the interrupt handler?  This would make _clear87 incompatible with 
>what it does today: the current version *always* clears the FPU.

 You are totally right  here.

>Also, what about _status87: shouldn't it be changed as well?

   I didn't even know this function :( 


Pierre Muller
Institut Charles Sadron
6,rue Boussingault
F 67083 STRASBOURG CEDEX (France)
mailto:muller AT ics DOT u-strasbg DOT fr
Phone : (33)-3-88-41-40-07  Fax : (33)-3-88-41-40-99