keyID is an unsigned char to identify which key to access.

The code shown is much simplified. My aim is when I change the number of keys used, I just make change in .h file but need not change anything in the .c file

If the variables were char, I can declare array of char and access them with index. like

usingned char foo(index) {
...
return variable(index);
}

Presently I use preprocessor directives to solve the problem because I don't think of any easy way to access sbits with index, and asking help for a better way.

It would be great if something like key[index] can access sbit.
Any comment will be welcome. Thanks for your attention.