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Accesing bit addressable variables

Elliot Chisholm

I was wondering what the "best" way to set a bit in a variable declared in the bit addressable area.

Originally I declared each bit as an sbit and therefore can set and clear them as follows

uint8_t bdata status ;
sbit enable = staus ^ 0 ;

enable = 1 ;
enable = 0 ;
I think it looks clearer to do as follows
#define ENABLE 0x01

uint8_t bdata status ;

status |= ENABLE ;
status &= ~ENABLE ;

but I am worried that this could less maintainable because there will be many #defines with the same values but related to different variables and confusion could ensue.

I was wondering what other people do and if there is a standard method for doing this?

Parents
  • 0 in reply to Graham Cole

    "Personally, I would always go for the first method as it is so much clearer." (my emphasis)

    I agree, although the OP thinks the opposite!

    "The only down-side is that the first method it is absolutly non-portable."

    But it can (I say should) be encapsulated in a macro, so that porting is simply a matter of suitably redefining the macro.
    Similarly for all other compiler-specifics.

    "The compiler will generate quite different code in each case."

    Absolutely.
    Why would Keil bother to dream up this special syntax if it made no difference?!

Reply
  • 0 in reply to Graham Cole

    "Personally, I would always go for the first method as it is so much clearer." (my emphasis)

    I agree, although the OP thinks the opposite!

    "The only down-side is that the first method it is absolutly non-portable."

    But it can (I say should) be encapsulated in a macro, so that porting is simply a matter of suitably redefining the macro.
    Similarly for all other compiler-specifics.

    "The compiler will generate quite different code in each case."

    Absolutely.
    Why would Keil bother to dream up this special syntax if it made no difference?!

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