Заполнить массив последовательными натуральными числами, идущими по спирали

Private Sub Command1_Click()
    Const n = 7
    Dim s(n, n) As Integer
    Dim i As Integer, j As Integer, k As Integer, p As Integer
    Dim z As String
    i = 0
    k = 0
    p = 1
    While i < n * n
        k = k + 1
        For j = k To n - k + 1
           i = i + 1
           s(k, j) = p
           p = p + 1
        Next
        For j = k + 1 To n - k + 1
           i = i + 1
           s(j, n - k + 1) = p
           p = p + 1
        Next
        For j = n - k To k Step -1
           i = i + 1
           s(n - k + 1, j) = p
           p = p + 1
        Next
        For j = n - k To k + 1 Step -1
           i = i + 1
           s(j, k) = p
           p = p + 1
        Next
    Wend
    For i = 1 To n
        For j = 1 To n
            z = z + CStr(s(i, j)) + vbTab
        Next
        z = z + vbCrLf
    Next
    Print z
End Sub

Sub main()
Dim S As Range, N%, C%, R%, I%, J%, dC%, dR%
Set S = Selection: S.ClearContents
N = S.Columns.Count
C = 1: R = 1: J = 1: S(1, 1) = 1
For I = 1 To 2 * N - 1
  dC = (2 - I Mod 4) Mod 2
  dR = (2 - (I - 1) Mod 4) Mod 2
  Do
    If C + dC > N Or C + dC < 1 Then Exit Do
    If R + dR > N Or R + dR < 1 Then Exit Do
    If S(R + dR, C + dC) Then Exit Do
    C = C + dC
    R = R + dR
    J = J + 1
    S(R, C) = J
  Loop
Next I
End Sub