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From: luisllo AT alumni DOT uv DOT es (Luis)
Newsgroups: comp.os.msdos.djgpp
Subject: Help with extended inline asm (or I'm stupid)
Date: 28 Feb 2002 08:57:51 -0800
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To: djgpp AT delorie DOT com
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Hi all!

I need to save the fpu state in order to be able to make a context
switch, in a multi-thread package I'm writting. I know how to do it in
assembler with a small function

__obt_flags:
    movl 4(%esp),%eax   #eax has the buffer address
    fsave (%eax)
    ret

I think that works fine, but I'm trying to do it with extended inline
asm,
inside my c code while compiling with djgpp's gcc. So I wrote a c
function
like this

int obt_flags (char* buffer)
{    
    asm (
        "fsave %0\n\t"
        : // no outputs
        : "m" (buffer)
        : "memory"
    ); 
}

void main(void)
{
    char buffer[108];

    obt_flags(buffer);
    printf("%s\n",buffer);
}

It compiles fine, but when executing it crashes with a sigsev FAULT,
when executing the print instruction.
Does anyone have any idea about where is the problem?, I guess it's
something very stupid, but I don't know how to fix it.

Thanks in advance!