[fpc-pascal] Pointer hashing

Ryan Joseph ryan at thealchemistguild.com
Mon Jan 30 03:37:06 CET 2017

I’m trying to hash a pointer value and found some example of hash function but not sure about translations and the process in general.

1) Should I cast “pointer” as PtrUInt to get an integer from a pointer? I’m looking for the memory address I guess and casting seems to return a unique value. Btw, these functions are for a 32 bit integer but I’m building for 64 bit. How do I deal with that? Can I remove the upper 32bits which are typically not used.

2) I’m getting incompatible type errors on my translation. What did I do wrong there? The fact the function is 32 bit may be the problem?

unsigned int hash(unsigned int x) {
    x = ((x >> 16) ^ x) * 0x45d9f3b;
    x = ((x >> 16) ^ x) * 0x45d9f3b;
    x = (x >> 16) ^ x;
    return x;

function Hash (x: PtrUInt): PtrUInt;
  x := (Power((x shr 16), x)) * $45d9f3b;
  x := (Power((x shr 16), x)) * $45d9f3b;
  x := Power((x shr 16), x);
  result := x;

Thanks for any ideas you have.

	Ryan Joseph

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