Dim Shared primes(9) As Uinteger = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29}

Type BigNum
    Dim Data(63) As Ubyte
End Type

Function compareBigNum(a As BigNum, b As BigNum) As Integer
    For i As Integer = 63 To 0 Step -1
        If a.data(i) > b.data(i) Then Return 1
        If a.data(i) < b.data(i) Then Return -1
    Next
    Exit Function
End Function

Sub multiplyBigNum(num As BigNum, factor As Uinteger)
    Dim As Ulongint carry = 0
    For i As Integer = 0 To 63
        Dim As Ulongint product = Clngint(num.data(i)) * factor + carry
        num.data(i) = product And 255
        carry = product Shr 8
    Next
End Sub

Function NSmooth(n As Uinteger, size As Integer) As BigNum Ptr
    Dim As Uinteger i, m, indicies(Ubound(primes))
    Dim As BigNum sgte(Ubound(primes))

    If n < 2 Or n > 521 Then
        Print "Argument 'n' out of range"
        Exit Function
    End If
    If size < 1 Then
        Print "Argument 'size' out of range"
        Exit Function
    End If

    Dim As Boolean ok = False
    For i = 0 To Ubound(primes)
        If n = primes(i) Then
            ok = True
            Exit For
        End If
    Next
    If Not ok Then
        For i = Ubound(primes) + 1 To 521
            If n = i Then
                ok = True
                Exit For
            End If
        Next
    End If
    If Not ok Then
        Print "Must be a prime number: "; n
        Exit Function
    End If

    Dim As BigNum Ptr ns = Callocate(size, Sizeof(BigNum))
    ns[0].data(0) = 1

    Dim As Uinteger sgteSize = 0
    For i = 0 To Ubound(primes)
        If primes(i) > n Then Exit For
        sgte(sgteSize).data(0) = primes(i)
        sgteSize += 1
    Next

    For m = 1 To size - 1
        Dim As BigNum minValue = sgte(0)
        For i = 0 To sgteSize - 1
            If compareBigNum(sgte(i), minValue) < 0 Then minValue = sgte(i)
        Next
        ns[m] = minValue
        For i = 0 To sgteSize - 1
            If compareBigNum(ns[m], sgte(i)) = 0 Then
                indicies(i) += 1
                sgte(i) = ns[indicies(i)]
                multiplyBigNum(sgte(i), primes(i))
            End If
        Next
    Next

    Return ns
End Function

Function BigNumToString(num As BigNum) As String
    Dim As String result = ""
    Dim As BigNum quotient, zeroNum, temp = num
    Dim As Uinteger divisor = 10

    Do
        Dim As Uinteger remainder = 0
        For i As Integer = 63 To 0 Step -1
            Dim As Ulongint dividend = (Clngint(remainder) Shl 8) Or temp.data(i)
            quotient.data(i) = dividend \ divisor
            remainder = dividend Mod divisor
        Next
        result = Chr(remainder + 48) & result
        temp = quotient
    Loop While compareBigNum(temp, zeroNum) > 0

    If Len(result) = 0 Then result = "0"
    Return result
End Function

' Main program
Dim As Uinteger i, j, p
Dim As BigNum Ptr ns

For i = 0 To Ubound(primes)
    p = primes(i)
    Print !"\nThe first "; p; " -smooth numbers are:"
    ns = NSmooth(p, 25)
    For j = 0 To 24
        Print BigNumToString(ns[j]); " ";
    Next
    Print
    Deallocate ns
Next

For i = 1 To Ubound(primes)
    p = primes(i)
    Print !"\nThe 3000 to 3002 "; p; " -smooth numbers are:"
    ns = NSmooth(p, 3002)
    For j = 2999 To 3001
        Print BigNumToString(ns[j]); " ";
    Next
    Print
    Deallocate ns
Next

Sleep