Re: Bitwsie operators in Lua

[David Jones <drj@...>]

David Jones wrote:
> Roberto Ierusalimschy wrote:
> > > Essentially any bitwise operation gets converted to a series 
> > > of       arithmetical 
> > > operations,                                                  
> >
> > That is all we wanted for Lua. But "not" and shifts are easy. Can you
> > give a viable implementation for or/and?
>
> Well, I was talking about specifying the meaning.  As for an 
> implementation, choose the simple portable approach: convert the 
> number to your favourite, C, integer type, do the operation in that 
> type, then convert back to whatever type you've chosen for numbers.  
> Sticking to double (for numbers) and int (for integers) and doing this 
> gives you a portable 32-bit implementation.  luaconf.h helps those who 
> want more. 


Or were you thinking of an approach where you change only the compiler 
and not the VM?  You can't reasonably do that, the implementation of 
"bitwise-and" is too tedious.  However with just "bitwise-and" or 
"bitwise-or" you can do all the others.

drj