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

Jon

Franklin

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

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- Stephen

PJAllen

·

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

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