excel vba test if specific bits set in integer code example

Example 1: excel vba test if specific bits set in integer

'Fast VBA function to test if specific bits are set 
'within a 16-bit Integer. If ALL specified bits are set then 
'this function returns True. If ANY of the specified bits are
'not set then this function returns False.

'Bits are numbered from 0 to 15, so the first (least significant) bit
'is bit 0.

'Note: bits can be specified in any order.
'Note: any number of bits can be specified in one call.


Function IntegerBitsAreSet(theInteger%, ParamArray bits()) As Boolean
    Static i&, b%()
    If UBound(bits) = -1 Then Exit Function
    If (Not Not b) = 0 Then
        ReDim b(0 To 14)
        For i = 0 To 14
            b(i) = 2 ^ i
        Next
    End If
    For i = 0 To UBound(bits)
        If bits(i) < 0 Then Exit Function
        If bits(i) > 14 Then Exit Function
        If (theInteger And b(Int(bits(i)))) = 0 Then Exit Function
    Next
    IntegerBitsAreSet = True
End Function


'----------------------------------------------------------------------------------------
MsgBox IntegerBitsAreSet(255, 7)           '<--displays: True     255 = 00000000 11111111
MsgBox IntegerBitsAreSet(230, 0)           '<--displays: False    230 = 00000000 11100110
MsgBox IntegerBitsAreSet(85, 0, 2, 6, 4)   '<--displays: True      85 = 00000000 01010101
MsgBox IntegerBitsAreSet(85, 0, 2, 5, 4)   '<--displays: False     85 = 00000000 01010101
MsgBox IntegerBitsAreSet(485, 2, 7, 5)     '<--displays: True     485 = 00000001 11100101
MsgBox IntegerBitsAreSet(24585, 14, 13, 3) '<--displays: True   24585 = 01100000 00001001        
'
'
'

Example 2: excel vba check if bit is set in integer

'Extremely fast VBA function to test if a specified bit is set 
'within a 16-bit Integer.

'Bits are numbered from 0 to 15, so the first (least significant) bit
'is bit 0.

'Note: we do not inspect bit 15, the sign bit.


Function IntegerBitIsSet(theInteger%, bit As Byte) As Boolean
    Static i&, b%()
    If (Not Not b) = 0 Then
        ReDim b(0 To 14)
        For i = 0 To 14
            b(i) = 2 ^ i
        Next
    End If
    If bit < 15 Then IntegerBitIsSet = theInteger And b(bit)
End Function

'------------------------------------------------------------------
MsgBox IntegerBitIsSet(255, 7)      '<--displays: True
MsgBox IntegerBitIsSet(230, 0)      '<--displays: False
MsgBox IntegerBitIsSet(16384, 14)   '<--displays: True
MsgBox IntegerBitIsSet(-16383, 0)   '<--displays: True