Trying to merge java.lang.Float, java.lang.Double with Classpath -- help wanted

Dalibor Topic robilad@kaffe.org
Mon Sep 22 11:50:00 GMT 2003


Andrew Haley wrote:
> Nathanael Nerode writes:
>  > >They are only GCJ-specific because they use CNI. There is nothing that 
>  > >is specific to any given VM implementation, ie a JNI implementation in 
>  > >classpath should work anywhere.
>  > 
>  > They depend on the bit encoding of doubles and floats.  This is not 
>  > specified on the Java Virtual Machine specification;
> 
> Yes it is; the Java VM requires IEEE-754.
> 
> http://java.sun.com/docs/books/vmspec/2nd-edition/html/Concepts.doc.html#33377

Yep, and the underlying C native code [1] may not be offering IEEE-754, 
as the ISO C standard doesn't specify a floating format, AFAIK. So you 
*may* need some abstraction/conversison layer between the OS 
representation of floating points and Java's representation of floating 
points.

At least if you're interested in portability to non-IEEE754 machines ;)

That's why I like Classpath's design better, but then, I'm not a gcj 
developer yet, maybe next year ;)

cheers,
dalibor topic

[1] If you are using C, of course. Things may be different for other 
languages.



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