It's just a matter of finding the position of the least significant (set) bit

It's probably quicker to just test that there are no bits set in the lowest 8 bits (64-52) of the mantissa. Those 8 bits are stored in the last (10th) byte of the real*10 representation. So it should just be a case of (assuming you have the 10 bytes packed in scalar) 

if( substr $packedReal10, -1 ) {
     warn 'Loss of precision...';
}

[download]
any Microsoft compiler that knows about long doubles will tell you that sizeof(long double) == sizeof(double) == 8.

Gah. How stupid is that. You know, I have a funny feeling that I saw a set of 80bit real math functions kicking around inside one of the system DLLs. In theory, it would be possible to wrap a header file and an import library around that and get access to them from C/C++. I can't remember where I (think) I saw them and a quick grep didn't locate them. I'll have another look later.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

In reply to Re^3: XS, C doubles and -Duselongdouble by BrowserUk
in thread XS, C doubles and -Duselongdouble by syphilis

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