Need to invert a bit in a byte

[Jonmar]

Howdy all,

I need to Invert a single "bit" in a Byte without disturbing any of the other bits.
Upon entering the needed subroutine, I will know which bit that I need to affect.
Also I need to do this with a minimal amount of code.
I am using a BS2e module.

Any suggestions would be appreciated.

Thanks in advance http://forums.parallax.com/images/smilies/smile.gif

Jon

[Franklin]

Will the bit be different each time through the subroutine or always the same bit?

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- Stephen

[PJ Allen]

·

somevariable VAR Byte

IF somevariable.BIT0 = 0 THEN
somevariable.BIT0 = 1
ELSE
somevariable.BIT0 = 0
ENDIF

[Tracy Allen]

whichBit VAR NIB ' 0 to 7 for bit number to flip
myVar VAR BYTE ' variable that needs that one bit flipped
here:
myVar = myVar ^ DCD whichBit
' the bit is now flipped


For example, if whichBit=5, then DCD whichBit will equal %00100000 with the fifth bit set, and then the XOR, ^ in PBASIC causes that one bit to flip.

Another way, using the fact that bits in a byte can be array-addressed counting up from bit 0:


whichBit VAR NIB ' 0 to 7 for bit number to flip
myVar VAR BYTE ' variable that needs that one bit flipped
here:
myVar.bit0(whichBit) = ~myVar.bit0(whichBit) ' ~ is PBASIC NOT operator
' the bit is now flipped

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Tracy Allen
www.emesystems.com (http://www.emesystems.com)

Post Edited (Tracy Allen) : 8/29/2008 4:44:37 AM GMT

[Jonmar]

Franklin,

Might be same bit, but usually a different bit each time through sub routine.

Jon