Binaryworld - RotateLeftI - Rotate an Integer to the left ... [ VB -> Math ]

' Rotate an Integer to the left the specified number of times
'
' NOTE: requires Power2()

Function RotateLeftI(ByVal value As Integer, ByVal times As Long) As Integer
  Dim i As Long, signBits As Integer

  ' no need to rotate more times than required
  times = times Mod 16
  ' return the number if it's a multiple of 16
  If times = 0 Then RotateLeftI = value: Exit Function

  For i = 1 To times
    ' remember the 2 most significant bits
    signBits = value And &HC000
    ' clear those bit and shift to the left by one position
    value = (value And &H3FFF) * 2
    ' if the number was negative, then add 1
    ' if bit 30 was set, then set the sign bit
    value = value Or ((signBits < 0) And 1) Or (CBool(signBits And &H4000) _
      And &H8000)
  Next
  RotateLeftI = value
End Function