Reading portion of a byte

[UncleJack]

I need to read the first four bits of a byte. Anyone know a way using VBA to do this?

Uncle Jack

 

[JohnYingling]

Dim byt As Byte
Dim bits4 As Long
bits4 = byt \ 16 ' Keep bits 7654 of 76543210
buts4 = byt mod 16 ' Keep bits 3210 of 76543210

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[MichaelRed]

Several requests for this (or minor variations lately). In todays world, it is generally considered a 'waste' to use any memory less than a "word" of memory for information storage. the generic rationale is that is requires more memory to sub-divide the memory unit (to retrieve the subdivided values) than to store each element as a "word", which may directly stored or retrieved. It is also much more prone to error, as there are no 'standard' routines to support bit manipulation. the following is offered more as an illustration of HOW the various bit values are defined than an actual manipulation mechanisim.

Public Function basByteMask(BytIn As Byte, Mask As Byte) As Byte

    'Michael Red 1/9/02
    'As usual, for illustration ONLY.

    'ByteIn is a BYTE (0-255)
    'Mask is a BYTE (0-255)
    'Returns a BYTE (0-255)
    'Note: Values of BIts in the Byte:
    '   (Bit #8) = &H80 = 128  (MSB)
    '   (Bit #7) = &H40 = 64
    '   (Bit #6) = &H20 = 32
    '   (Bit #5) = &H10 = 16
    '   (Bit #4) = &H08 = 08
    '   (Bit #3) = &H04 = 04
    '   (Bit #2) = &H02 = 02
    '   (Bit #1) = &H01 = 01    (LSB)
    '   (Bit #7) = &H00 = 00    (Empty - Would ALWAYS Return 0)

    basByteMask = BytIn And Mask

End Function

MichaelRed
m.red@att.net

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