//private static uint CalculateHash(byte[] buf, int len = -1, uint seed = 0)
//{
// uint h32;
// int index = 0;
// if (len == -1)
// {
// len = buf.Length;
// }
// if (len >= 16)
// {
// int limit = len - 16;
// uint v1 = seed + PRIME32_1 + PRIME32_2;
// uint v2 = seed + PRIME32_2;
// uint v3 = seed + 0;
// uint v4 = seed - PRIME32_1;
// do
// {
// v1 = CalcSubHash(v1, buf, index);
// index += 4;
// v2 = CalcSubHash(v2, buf, index);
// index += 4;
// v3 = CalcSubHash(v3, buf, index);
// index += 4;
// v4 = CalcSubHash(v4, buf, index);
// index += 4;
// } while (index <= limit);
// h32 = RotateLeft(v1, 1) + RotateLeft(v2, 7) + RotateLeft(v3, 12) + RotateLeft(v4, 18);
// }
// else
// {
// h32 = seed + PRIME32_5;
// }
// h32 += (uint)len;
// while (index <= len - 4)
// {
// h32 += BitConverter.ToUInt32(buf, index) * PRIME32_3;
// h32 = RotateLeft(h32, 17) * PRIME32_4;
// index += 4;
// }
// while (index < len)
// {
// h32 += buf[index] * PRIME32_5;
// h32 = RotateLeft(h32, 11) * PRIME32_1;
// index++;
// }
// h32 ^= h32 >> 15;
// h32 *= PRIME32_2;
// h32 ^= h32 >> 13;
// h32 *= PRIME32_3;
// h32 ^= h32 >> 16;
// return h32;
//}
private static XxhState Init(XxhState state, uint seed = 0)
{
if (state.Memory != null)
{
return(state);
}
state.Seed = seed;
state.V1 = seed + Prime321 + Prime322;
state.V2 = seed + Prime322;
state.V3 = seed + 0;
state.V4 = seed - Prime321;
state.TotalLen = 0;
state.Memsize = 0;
state.Memory = new byte[16];
return(state);
}
private static uint Digest(XxhState state)
{
uint h32;
var index = 0;
if (state.TotalLen >= 16)
{
h32 = RotateLeft(state.V1, 1) +
RotateLeft(state.V2, 7) +
RotateLeft(state.V3, 12) +
RotateLeft(state.V4, 18);
}
else
{
h32 = state.Seed + Prime325;
}
h32 += (UInt32)state.TotalLen;
while (index <= state.Memsize - 4)
{
h32 += Peek4(state.Memory, index) * Prime323;
h32 = RotateLeft(h32, 17) * Prime324;
index += 4;
}
while (index < state.Memsize)
{
h32 += state.Memory[index] * Prime325;
h32 = RotateLeft(h32, 11) * Prime321;
index++;
}
h32 ^= h32 >> 15;
h32 *= Prime322;
h32 ^= h32 >> 13;
h32 *= Prime323;
h32 ^= h32 >> 16;
return(h32);
}
private static XxhState Update(byte[] input, int len, XxhState state)
{
int index = 0;
state.TotalLen += (uint)len;
if (state.Memsize + len < 16)
{
Array.Copy(input, 0, state.Memory, state.Memsize, len);
state.Memsize += len;
return(state);
}
if (state.Memsize > 0)
{
Array.Copy(input, 0, state.Memory, state.Memsize, 16 - state.Memsize);
state.V1 = CalcSubHash(state.V1, state.Memory, index);
index += 4;
state.V2 = CalcSubHash(state.V2, state.Memory, index);
index += 4;
state.V3 = CalcSubHash(state.V3, state.Memory, index);
index += 4;
state.V4 = CalcSubHash(state.V4, state.Memory, index);
//index += 4;
index = 0;
state.Memsize = 0;
}
if (index <= len - 16)
{
int limit = len - 16;
uint v1 = state.V1;
uint v2 = state.V2;
uint v3 = state.V3;
uint v4 = state.V4;
do
{
v1 = CalcSubHash(v1, input, index);
index += 4;
v2 = CalcSubHash(v2, input, index);
index += 4;
v3 = CalcSubHash(v3, input, index);
index += 4;
v4 = CalcSubHash(v4, input, index);
index += 4;
} while (index <= limit);
state.V1 = v1;
state.V2 = v2;
state.V3 = v3;
state.V4 = v4;
}
if (index < len)
{
Array.Copy(input, index, state.Memory, 0, len - index);
state.Memsize = len - index;
}
return(state);
}
