// Use this if and only if 'Denial of Service' attacks are not a concern (i.e. never used for free-form user input),
// or are otherwise mitigated
internal unsafe int GetNonRandomizedHashCode()
{
fixed(char *src = &_firstChar)
{
Debug.Assert(src[this.Length] == '\0', "src[this.Length] == '\\0'");
Debug.Assert(((int)src) % 4 == 0, "Managed string should start at 4 bytes boundary");
uint hash1 = (5381 << 16) + 5381;
uint hash2 = hash1;
uint *ptr = (uint *)src;
int length = this.Length;
while (length > 2)
{
length -= 4;
// Where length is 4n-1 (e.g. 3,7,11,15,19) this additionally consumes the null terminator
hash1 = (BitOps.RotateLeft(hash1, 5) + hash1) ^ ptr[0];
hash2 = (BitOps.RotateLeft(hash2, 5) + hash2) ^ ptr[1];
ptr += 2;
}
if (length > 0)
{
// Where length is 4n-3 (e.g. 1,5,9,13,17) this additionally consumes the null terminator
hash2 = (BitOps.RotateLeft(hash2, 5) + hash2) ^ ptr[0];
}
return((int)(hash1 + (hash2 * 1566083941)));
}
}
private static void Block(ref uint rp0, ref uint rp1)
{
uint p0 = rp0;
uint p1 = rp1;
p1 ^= p0;
p0 = BitOps.RotateLeft(p0, 20);
p0 += p1;
p1 = BitOps.RotateLeft(p1, 9);
p1 ^= p0;
p0 = BitOps.RotateLeft(p0, 27);
p0 += p1;
p1 = BitOps.RotateLeft(p1, 19);
rp0 = p0;
rp1 = p1;
}
private static uint MixState(uint v1, uint v2, uint v3, uint v4)
{
return(BitOps.RotateLeft(v1, 1) + BitOps.RotateLeft(v2, 7) + BitOps.RotateLeft(v3, 12) + BitOps.RotateLeft(v4, 18));
}
private static uint QueueRound(uint hash, uint queuedValue)
{
return(BitOps.RotateLeft(hash + queuedValue * Prime3, 17) * Prime4);
}
private static uint Round(uint hash, uint input)
{
return(BitOps.RotateLeft(hash + input * Prime2, 13) * Prime1);
}
