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Date: Thu, 03 Mar 2005 20:15:08 +1300
From: Danny Smith <dannysmith AT clear DOT net DOT nz>
Subject: Re: loading of wsock32 disturbs FPU
To: Cygwin <cygwin AT cygwin DOT com>
Reply-to: Danny Smith <dannysmith AT users DOT sourceforge DOT net>
Message-id: <000701c51fc0$bc678550$f14861cb@DANNY>
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cgf wrote:
>On Wed, Mar 02, 2005 at 03:37:42PM +0100, Corinna Vinschen wrote:
>>On Mar  2 15:31, Corinna Vinschen wrote:
>>>On Mar 2 13:33, Dave Korn wrote:
>>>>Hm.  We probably need to put a finit instruction into the autoload code
>>>>somewhere.  wsock_init () looks like just the place......  now if I
>>>>just persuade the CVS code to build without a SIG11 (grmbl grmbl....)
>>>
>>>Hmm?  -v please.
>>
>>I just added an finit call to wsock_init and it seems to work fine.
>>
>>Are there any non-FPU CPUs >= i386 out there which would choke on this
>>machine instruction?  I guess not, but I'm not exactly fluent in ix86
>>history...
>
>I mentioned to Corinna on irc that I don't think that just calling finit
>is the right way to handle this.  What if someone had already set the
>precision as they liked?  Then loading winsock would reset it.
>
>cgf

Seeing this I got a fright, thinking mingw would have the same problem, with
very bad consequences for eg,
libgcj.a, which _always_ loads ws2_32.dll, and many, many other projects

But no, I get:

FPU test OK
FPU test OK
FPU test OK
FPU test OK

I think ws2_32.dll calls _fpreset() which is normally supplied by msvcrt.dll
Mingw provides its own _fpreset  in libmingwex.a (crt_fp10.o) )  which  sets
64-bit mantissa so all is well

If I load in mingw's crt_fp8.o module, which provides a stub for the msvcrt.dll
import  _fpreset,  I get the error.

A cygwin version of _fpreset (that calls finit) should do the trick, without the
overhead of  fpu environment  sav and restore

Danny




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