workaround for a pointer to bit

Compiler does not allow me to have bit type in a record, or a pointer to bit type. Looking at bit type of DI_1 described in compiler generated U file I have found that this:

is translated to a compiler friendly form like this:

As expected, it seams that it is not a simple pointer but a record of a byte pointer and a bit number in that byte. I am trying to trick compiler to accept this bit (or bit8) type in a array of records (as const or structconst), but without any success at all. I could store this bit8 type in a record as word and byte but I do not know how to cast to/from it.

I would like to have something like this:

and then later in code to use it for read/write from/to that bit:

I already have this working with a pointer to a byte type in ram and eeprom, but bit type is giving me a headache.

If anyone has any idea I am all ears... :argue:

Hello Merlin,

I am aware of bitsets but they are not applicable in my case. I am building a communication protocol where some of the supported commands read and write digital and analog tags (real IO signals and runtime variables), and some settings stored in eeprom. I have already built supporting structures and everything works well for byte and higher types. For example I have a const array of records which holds implemented tag number, it's storage type (ram, eep), and a pointer to a tag in ram (like I[@PinA]) or to a tag in eep. Now for reading and writing them I simply look up for a tag number, and if found I get/set it's value based on tag storage type (ram/eep). Whole list of implemented tags is stored in a single const array, and both getting and setting functions use the same list. Unfortunately with bits, if I do not find a solution I will have to avoid this elegant const array solution and I will have to hard code separate case.. endcase for gettings bit tags, and separate case..endcase for setting tags, and to maintain the same list at two places in code. Very ugly, so I am all ears for any helpful workaround suggestion or AvrCo improvement in this field.

Hello Merlin,

I still think that it could be done. If we look at a bit type as a structure of one word (for address) and one byte (for a bit number), then pointer to a bit type would be a pointer to a structure that is always the same for all bit types, so dereferencing it should be possible. In my imaginary example shown above DI_1 already exists and is declared, and I want to store a pointer to DI_1 into const array element. That could be done if a pointer to bit or bit8 type would be possible as in my example. Then in runtime I just dereference the pointer to bit/bit8 type to get or set value of this bit. Simple and clean.

I was kind of hoping for some quick hokus-pokus on the Rolf side and enabling what seamed to already exist in the compiler but not yet available for general use, but if it's too much work I will maintain the bits different then other types and code each bit manually with case..endcase. Having bit type in a record was nice idea, but sometimes you just can't have it all.

Thanks!