Adding without adding - Printable Version

Adding without adding - Printable Version

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Adding without adding - SMcNeill - 05-11-2022

So, how do you add two numbers, without adding them?

Code: (Select All)
Print Add(200, 22, Overflow~%%);: If Overflow~%% Then Print "Overflow!" Else Print

Print Add(245, 22, Overflow~%%);: If Overflow~%% Then Print "Overflow!" Else Print

Function Add (A As _Unsigned _Byte, B As _Unsigned _Byte, Overflow As _Unsigned _Byte)

    Dim As _Unsigned _Byte CarryFlag

    Overflow = 0

    While B <> 0

        CarryFlag = A And B

        Overflow = Overflow Or _SHR(CarryFlag, 7)

        A = A Xor B

        B = _SHL(CarryFlag, 1)

    Wend

    Add = A

End Function

You XOR, Bit shift, and AND them into submission! Big Grin