Macro Explanation Please!

[Guest]

Hi,

I am using these wonderful macros that I found on the board to deal with individual i/o pins:

[Ttelmah]

#define set_bit_var(x) bit_set(*(int8 *)(x >> 3), x & 7)

OK. The first '*', says 'use this pointer'. The second is a 'cast'. The little bit in the bracket, 'converts' the value that follows, 'into' a pointer of type 'int *' (pointer to an integer). Up to this point, what follows, is an integer. the bracketted bit, tells the compiler to treat this integer as if it was a pointer. The first *, then uses this as a pointer!.

Best Wishes

[Guest]

Brilliant, a concise and crystal clear explanation - now my curiosity is satisfied - thank you very much!

Regards,

John