Re: Java virtual machine as target language for C/C++

Drinie@xs4all.nl says...
>I know that Java does not support pointer arithmetic.
>
>But as the Java virtual machine gets integrated in many OSes it would
>be nice to use it as a target language for other languages.
>
>Is it possible (and will Sun allow it) to extend the JVM to support
>pointer arithmetic.


No. This would be extremely unpopular, as it would completely invalidate
Java's much-touted security.


However, it would be possible to emulate a C environment using a simple
byte array. A C pointer would translate into an array offset, and
all the pointer arithmetic and arbitrary casts of types could be
supported. With a smart JIT compiler, you may even get just as
efficient code. You'd have to port malloc(), free(), and the rest of
the standard C library, but that should be pretty straightforward:
they could all be methods of a C emulator class that would also
implement the memory-access primitives.


You'd get memory leaks, invalid pointers, and all the rest of the
problems you get from normal C, but you wouldn't need to change a
line of your legacy code, and you wouldn't be able to jeopardize
anything outside the 'anything goes' byte-array memory space.
Attempts to access values outside the byte-array would throw
an exeption (perhapse we could call it GPF!)


-Eugene


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