[Vm-dev] Simple question about objects, headers and sizes

Javier Pimás elpochodelagente at gmail.com
Wed Jun 8 15:36:32 UTC 2011

Thanks! That's exactly what I needed to know!

On Tue, Jun 7, 2011 at 11:28 AM, Bert Freudenberg <bert at freudenbergs.de>wrote:

> On 06.06.2011, at 08:46, Javier Pimás wrote:
> >  A better question would be, what is the bit format of the extra header?
> See the class comment for ObjectMemory:
> "If a class is in the compact class table, then this is the only header
> information needed.  If it is not, then it will have another header word at
> offset -4 bytes with its class in the high 30 bits, and the header type
> repeated in its low 2 bits.  It the objects size is greater than 255 bytes,
> then it will have yet another header word at offset -8 bytes with its full
> word size in the high 30 bits and its header type repeated in the low two
> bits."
> - Bert -

Javier Pimás
Ciudad de Buenos Aires
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