Rabin-Miller Primality Test

[storm5510]

I'm having problems transposing this pseudo-code into something usable. Perhaps someone could lend a hand?

Pseudo-code:

Input: n > 2, an odd integer to be tested for primality;

Input: k, a parameter that determines the accuracy of the test

Output: composite if n is composite, otherwise probably prime

write n − 1 as 2s·d with d odd by factoring powers of 2 from n − 1

LOOP: repeat k times:
pick a randomly in the range [2, n − 1]
x = ad mod n
if x = 1 or x = n − 1 then do next LOOP
for r = 1 .. s − 1
x = x2 mod n
if x = 1 then return composite
if x = n − 1 then do next LOOP
return composite
return probably prime

What I have:

Private Sub Form_Load()

Dim K As Long
Dim N As Long
Dim A As Long
Dim X As Long
Dim D As Long

Dim Prime As Boolean

N = 23
K = 11
D = 3
Prime = True

For A = 3 To K Step 2
    DoEvents
    X = (A * D) Mod N
    If X < (X ^ 2) Mod N Then
        If X = 1 Then
            Prime = False
        End If
    End If
Next

Debug.Print Prime
End

End Sub

I am manually assigning numbers for testing. I use "DoEvents" in case I end up with a run-away loop so I can stop it without a crash.