> It's close but not entirely correct. The computation needs to include the
> extra header word for "large" instances (> 255 bytes). Squeak has three
> possible header sizes:
>
> 1 header word - used by compact classes
> 2 header words - used by regular classes
> 3 header words - used by "large" instances
>
> BTW, SpaceTally>>spaceForInstancesOf:withInstanceCount: has the correct
> computation (except for 64 bit :-)
>
>
Ok, perfect. Thanks :)
>
> Is there a way to know this
>> but from the VM side also ? how ?
>> I really need it from the VM side :( but I have no idea how to do it.
>>
>
> It's easy to do in the VM, just use this:
>
> primitiveByteSize
> "Answers the number of bytes the receiver occupies"
>
> | nbytes|
> self export: true.
> oop := self popStack.
> nbytes := (self sizeBitsOf: oop) + (self extraHeaderBytes: oop).
> self pushInteger: nbytes.
>
>
I tried this and seems to work ok. I don't really need a primitive but an
internal method that is called by a primitive. So, I did something like
this:
internalByteSize: anOop
"Answers the number of bytes the receiver occupies"
| nbytes|
self inline: true.
nbytes := (self sizeBitsOf: anOop) + (self extraHeaderBytes: anOop).
^ nbytes.
and then I call it like this for example:
oop := self firstAccessibleObject.
[oop = nil] whileFalse: [
(self isIntegerObject: oop)
ifFalse: [
size := self internalByteSize: oop.
......]
oop := self accessibleObjectAfter: oop.
].
but internalByteSize ALWAYS return me the same value...do you know what can
be wrong ?
Thanks in advance
Mariano
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