excelvba test if specific bits are set in byte code example

Example 1: excel vba are bits set in byte

'Fast VBA function to test if specific bits are set 
'within a Byte. 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 7, so the first (least significant) bit
'is bit 0.

'Note: bits can be specified in any order.


Function ByteBitsAreSet(theByte As Byte, ParamArray bits()) As Boolean
    Static i&, b() As Byte
    If UBound(bits) = -1 Then Exit Function
    If (Not Not b) = 0 Then
        ReDim b(0 To 7)
        For i = 0 To 7
            b(i) = 2 ^ i
        Next
    End If
    For i = 0 To UBound(bits)
        If bits(i) < 0 Then Exit Function
        If bits(i) > 7 Then Exit Function
        If (theByte And b(Int(bits(i)))) = 0 Then Exit Function
    Next
    ByteBitsAreSet = True
End Function


'--------------------------------------------------------------------------
MsgBox ByteBitsAreSet(255, 7)           '<--displays: True   255 = 11111111
MsgBox ByteBitsAreSet(230, 0)           '<--displays: False  230 = 11100110
MsgBox ByteBitsAreSet(85, 0, 2, 6, 4)   '<--displays: True    85 = 01010101
MsgBox ByteBitsAreSet(85, 0, 2, 5, 4)   '<--displays: False   85 = 01010101
'
'
'

Example 2: excel vba is bit set long

'Extremely fast VBA function to test if a specified bit is set 
'within a 32-bit Long integer.

'Bits are numbered from 0 to 31, so the first (least significant) bit
'is bit 0.

'Note: we do not inspect bit 31, the sign bit.
'Note: any number of bits can be specified in one call.


Function LongBitIsSet(theLong&, bit As Byte) As Boolean
    Static i&, b&()
    If (Not Not b) = 0 Then
        ReDim b(0 To 30)
        For i = 0 To 30
            b(i) = 2 ^ i
        Next
    End If
    If bit < 31 Then LongBitIsSet = theLong And b(bit)
End Function


'------------------------------------------------------------------
MsgBox LongBitIsSet(255, 7)             '<--displays: True
MsgBox LongBitIsSet(230, 0)             '<--displays: False
MsgBox LongBitIsSet(16384, 14)          '<--displays: True
MsgBox LongBitIsSet(-16383, 0)          '<--displays: True
MsgBox LongBitIsSet(&H7FFFFFFF, 0)      '<--displays: True

Example 3: excel vba set bit in byte

'Extremely fast VBA function to test if a specified bit is set 
'within a Byte.

'Bits are numbered from 0 to 7, so the first (least significant) bit
'is bit 0.

Function ByteBitIsSet(theByte As Byte, bit As Byte) As Boolean
    Static i&, b() As Byte
    If (Not Not b) = 0 Then
        ReDim b(0 To 7)
        For i = 0 To 7
            b(i) = 2 ^ i
        Next
    End If
    If bit < 8 Then ByteBitIsSet = theByte And b(bit)
End Function

'------------------------------------------------------------------
MsgBox ByteBitIsSet(255, 7)      '<--displays: True
MsgBox ByteBitIsSet(230, 0)      '<--displays: False