On Fri, Aug 4, 2017 at 8:29 AM, Christopher Li <sparse@xxxxxxxxxxx> wrote:
>
> There is a few design choice here. We can make ptr==NULL for the condition
> of ptr is marked deleted. We can also use tags to do the marking. Using tags
> will allow NULL pointer as valid entry in the ptrlist.
I think what might be a good idea is to simply replace the "nr" in
"ptr_list" with a bitmap of entries instead.
We already limit each ptr_list[] to 29 entries, so making it an
"unsigned int" bitmap instead wouldn't be hard. So it would be just a
single-bit "tag" whether an entry is present or not.
And that allows easy deletion, easy insertion and easy to iterate over too.
The insertion is admittedly a *bit* awkward, since you have to find a
free bit, but it's either a fairly simple loop or on newer CPU's you
can use the "find first bit" instruction.
Linus
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