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  1. #1
    Join Date
    Jun 2011
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    Indian Harbour Nova Scotia
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    Default inverting all bits in a byte

    How do I invert all the bits in a byte?

    Eg %011010110 would become %100101001

    I assumed, then read it was by using the tilde (~) function but I'm having trouble using it in code.

    eg if I had byteA=%011010110

    and I did this: byteA=~byteA, shouldn't ~byteA display %100101001?

    Strangely I can display the value of byteA in the display (LabX1) but ~byteA comes up empty.

  2. #2
    Join Date
    May 2013
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    australia
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    Default Re: inverting all bits in a byte

    how many bits in a byte ? not 9


    Eg %011010110 would become %100101001
    Strangely I can display the value of byteA in the display (LabX1) but ~byteA comes up empty.
    what display? , how displayed ?
    if its a common garden variety lcd , chrs in this range 127 < chr >160 are not in the built in font
    so using var A = $66
    A will print on lcd
    ~A ($99) will not print on lcd
    This is more entertaining than Free to Air TV

  3. #3
    Join Date
    Apr 2014
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    Northeast
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    234

    Default Re: inverting all bits in a byte

    There is a simple ASM command, COMF. This is what it would look like:

    @ BANKSEL _byteA
    @ COMF _byteA, F

    The first line moves the BSR (Bank Select Register) to the BANK containing your variable. The variable is preceded by an underscore for ASM; _byteA.

    The second line executes the command, Compliment F (F is your variable). The appending ", F" puts the result back in your variable, byteA.

    Hope this helps

  4. #4

    Default Re: inverting all bits in a byte

    Use the ^ operator for Bitwise Exclusive OR

    ByteA = ByteA ^ %11111111 Inverts the bits of ByteA

  5. #5
    Join Date
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    Default Re: inverting all bits in a byte

    thanks Dick

  6. #6
    Join Date
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    Default Re: inverting all bits in a byte

    I have the new "enhanced" byte, with 9 bits.

  7. #7
    Join Date
    Aug 2003
    Location
    Australia
    Posts
    980

    Default Re: inverting all bits in a byte

    Using comf would be about twice as fast there since you don’t have to do anything at all with the literal 0xFF.

  8. #8
    Join Date
    Jan 2006
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    Istanbul
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    Default Re: inverting all bits in a byte

    Why not just use grandpa's way:

    byte = 255- byte

    Inverts the bits.
    "If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte

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