RE: [avr-libc-dev] What about to unify _SFR's macroses?

[Weddington, Eric]

> -----Original Message-----
> From: 
> address@hidden 
> [mailto:address@hidden
> org] On Behalf Of Dmitry K.
> Sent: Saturday, May 03, 2008 3:33 PM
> To: address@hidden
> Subject: [avr-libc-dev] What about to unify _SFR's macroses?
> 
> Hi.
> 
> We have 3 variants of SFR usage:
>   1. This is default for C/C++.  Port names are like common variables.
>   2. Port names are defined as ordinary numbers, suitable to use with
>   IN/OUT instructions.
>   3. Port names are defined as ordinary numbers (addresses), suitable
>   to use with LDS/STS instruction.
> 
> The next is too complex to understand (IMHO, worse):
>   . With variant #2 the _SFR_MEM_ADDR() returns correct 
> address only for
>   ports higher than SREG.  For smaller ports it returns the 
> port number,
>   ie value suitable for IN/OUT.
>   . With variant #2 the _SFR_ADDR() works correct for C/C++ 
> source only.
>   For ASM it is not defined.
>   . There is no method to determine the address of ports 
> (those <= 0x5F)
>   in ASM source.
> 
> What about to change the _SFR macroses:
>   . _SFR_MEM_ADDR() must return address for all ports in all variants.
>   . _SFR_ADDR() must be defined in both ASM variants.
>   . In addition to cryptic __SFR_OFFSET (used for choice the variant)
>   add clean macroses to set compatibility level, like:
>       #define _SFR_ASM_COMPAT _SFR_ASM_IOPORT
> 
> Note, the _SFR_IO_ADDR() and _SFR_IO_REG_P() work correct in 
> all cases.
> With proposed changes the _SFR_MEM_ADDR() and _SFR_ADDR() 
> would be equal.
> 
> Also, I prefer to have default for ASM the variant #3: this 
> is compatible
> with old programs and corresponds to Atmel's datasheet 
> examples. However,
> it too late to change.
> 
> Please, opinions.

I agree that it is a mess and it would be nice to be cleaned up.

Do you have a patch available that shows the changes you describe?

Eric