Q: purpose of hashtable_hash_ptr

[scossu]

Newbie here, so please bear with me, but I think I am missing something obvious.

What is the purpose of hashtable_hash_ptr @ https://github.com/srdja/Collections-C/blob/master/src/hashtable.c#L918 ? My understanding is that it would take a pointer value and compute a hash of it.

But since a pointer is 4-8 bytes in most systems, would it not be more convenient to just use the pointer value itself as the "hash" and save the hashing operations?

Thanks.

[Kobzol]

Usually you want your hash function to distribute the values evenly in the hashtable. Values of pointers tend to be clumped together. Also pointers are usually aligned to N-bytes, so the last log2(N) bits are zero, therefore after doing modulo of the hash table size, even more values would clump together.