SuperFastHash

#include <Windows.h>

PVOID CopyMemoryEx(_Inout_ PVOID Destination, _In_ CONST PVOID Source, _In_ SIZE_T Length)
{
	PBYTE D = (PBYTE)Destination;
	PBYTE S = (PBYTE)Source;

	while (Length--)
		*D++ = *S++;

	return Destination;
}

SIZE_T StringLengthW(_In_ LPCWSTR String)
{
	LPCWSTR String2;

	for (String2 = String; *String2; ++String2);

	return (String2 - String);
}


UINT16 Read16BitsAlignedSafe(PVOID Pointer)
{
	UINT16 Value;

	CopyMemoryEx(&Value, Pointer, sizeof(Value));

	return Value;
}

UINT HashStringSuperFastHashW(PWCHAR String, INT Length)
{
	UINT32 Hash = (UINT32)Length;
	UINT32 TempObject = 0;
	INT Remainder = 0;

	Remainder = Length & 3;
	Length >>= 2;

	for (; Length > 0; Length--)
	{
		Hash = Read16BitsAlignedSafe(String);
		TempObject = (Read16BitsAlignedSafe(String + 2) << 11) ^ Hash;
		Hash = (Hash << 16) ^ TempObject;
		String += 4;
		Hash += Hash >> 11;
	}

	switch (Remainder)
	{
		case 3:
		{
			Hash += Read16BitsAlignedSafe(String);
			Hash ^= Hash << 16;
			Hash ^= (UINT32)String[2] << 18;
			Hash += Hash >> 11;
			break;
		}
		case 2:
		{
			Hash += Read16BitsAlignedSafe(String);
			Hash ^= Hash << 11;
			Hash += Hash >> 17;
			break;
		}
		case 1:
		{
			Hash += (UCHAR)String[0];
			Hash ^= Hash << 10;
			Hash += Hash >> 1;
			break;
		}
		default:
			break;
	}

	Hash ^= Hash << 3;
	Hash += Hash >> 5;
	Hash ^= Hash << 4;
	Hash += Hash >> 17;
	Hash ^= Hash << 25;
	Hash += Hash >> 6;

	return Hash;
}

INT main(VOID)
{
    WCHAR StringHashExample[] = L"Hash This String";
    UINT Hash = 0;

	  Hash = HashStringSuperFastHashW(StringHashExample, (INT)(StringLengthW(StringHashExample) * sizeof(WCHAR)));

    return ERROR_SUCCESS;
}