excel vba check if specific bits set in byte

vba check if specific 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
'
'
'

Posted by: Guest on February-06-2021

Source

'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. 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

'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

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