/// <summary>
/// perform transformatio using i (c^(b|~d))
/// </summary>
static unsafe void TransI(ref uint a, uint b, uint c, uint d, uint k, ushort s, uint i, uint *X)
{
a = b + Md5.RotateLeft((a + (c ^ (b | ~d)) + X[k] + T[i - 1]), s);
}
/// <summary>
/// perform transformatio using f(((b&c) | (~(b)&d))
/// </summary>
static unsafe void TransF(ref uint a, uint b, uint c, uint d, uint k, ushort s, uint i, uint *X)
{
a = b + Md5.RotateLeft((a + ((b & c) | (~(b) & d)) + X[k] + T[i - 1]), s);
}