Re: fine points of dynamic memory allocation, not 80286 protected mode

According to Scott Lurndal <slp53@pacbell.net>:

I suppose it's possible, but the versions I know keep free lists
and consolidate adjacent free chunks which requires comparing the
pointers.

>
Assuming the malloc implementation associates metadata with the
allocation (e.g. in bytes either before the returned pointer or
after the allocation), the comparision for consolidation should
always be standard supported equality comparisons.

I've seen allocators that sort the free list.  And then there's
other approches like buddy allocators that futz directly with
the address bits.

You probably could write a malloc/free that worked without doing
anything other than equality comparisons but I doubt it would be a
very good ones. The real ones I've seen also have tons of defensive
compares to try to check for pointer smashing.


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