'Variables used by the functions
Dim Shared N(0) As Byte, BigN As Long
Dim Shared CurN As Long 'Sliding Variable


'Generate the next number in the sequence
Public Function rndGenRand() As Byte
    Dim NexN As Long, PreN As Long, Ret As Byte

    'Obtain the previous and next buffered values
    PreN = CurN - 1: If PreN = 0 Then PreN = BigN
    NexN = CurN + 1: If NexN > BigN Then NexN = 1

    'Calculate the new value
    N(CurN) = N(PreN) XOr N(NexN)

    'Increment sliding variable
    Ret = N(CurN): CurN = CurN + 1
    If CurN > BigN Then CurN = 1

    'Return the value
    rndGenRand = Ret
End Function


'Initialize the number generator
Public Sub rndInit(HistCount As Long)
    Dim Q As Integer

    'Redimension array with new value
    BigN = HistCount
    ReDim N(1 To BigN) As Byte

    'Initialize the array
    N(1) = &HFF
    For I = 2 To BigN - 1
        N(I) = Q: Q = Q + 37
        If Q > 255 Then Q = Q - 255

    Next

    'Set up sliding variable
    CurN = BigN

    'Run a few startup mixing cycles
    For I = 1 To 50: rndGenRand: Next
End Sub

'Calculates the angle to a point
Public Function AngleToPoint(Horz As Double, Vert As Double) As Double
Dim Temp As Double

If Horz = 0 Then 'Undefined slope
    If Vert > 0 Then Temp = Pi / 2
    If Vert = 0 Then Temp = 0
    If Vert < 0 Then Temp = Pi * 1.5
Else 'Defined slope
    Temp = Atn(Vert / Horz)
    If Horz < 0 Then Temp = Temp + Pi
    If Temp < 0 Then Temp = Temp + 2 * Pi
End If

'Return the value
AngleToPoint = Temp
End Function