How to add new immediate types (was: Re: Adding a new imediate type)

Georg Gollmann gollmann at
Wed Jan 4 08:13:00 UTC 2006

Am 04.01.2006 um 00:34 schrieb Andreas Raab:
> So what one could do is to use that formerly unused bit pattern for  
> "something different". But wait! Unfortunately, the bit pattern is  
> not-so-unused after all; the garbage collector makes use of it (see  
> the definition of HeaderTypeGC in ObjectMemory) to flag objects  
> that are currently being marked. This needs to be fixed before the  
> bit pattern can be used and I'll leave that as an exercise for the  
> interested reader because it's a strict prerequisite for anything  
> that follows below and can be done independently (HINT: A cheap way  
> out -and yes, there are others- is to relocate that bit; most  
> people are likely just as happy with half of the addressable memory).

Don´t go back to the bad old days when Squeak could not run on some  
operating systems since it had to live in the lower half of the  
address space !
According to Dan the 64-bit effort finally made Squeak 32-bit clean.  
Keep it that way.


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