AVR-Chat

So ... after the big discussion on  bit-shifting and masking I decided
to rewrite a bit of pretty rough wireless code I use a lot with my new
found appreciation of making my code more portable and tidy-er. 

But! To my dismay I found that the codevision header files dont
contain defines for bits like SPIF in the SPSR (SPI status register)
do the other compilers like GCC and IAR have header files that have
the names of each bit of every register defined ?

I did end up rewriting the code, and to me it is now a thing of
beauty, but I had to go through the header file and #define all the
bits I was using for shift and masking.

Cheers
Hein B
Auckland
New Zealand



--- In AVR-Chat@yahoogroups.com, Ned Konz <ned@...> wrote:
>
> I wrote:
> 
> > So, using my headers, your example test for tx completed or empty
could 
> > be written:
> > 
> 
> [snip]
> 
> >        if (UCSR0B & ((1 << bitTXC0) | (1 << bitUDRE0)))
> >           /* do stuff */
> > 
> > 
> > and the generated code would look like this:
> 
> [snip]
> 
> > or this (somewhat more efficient):
> > 
> > 
> >    15:test2.c  ***       if (UCSR0B & ((1 << bitTXC0) | (1 <<
bitUDRE0)))
> > 
> >   324 0010 8AB1      		in r24,42-0x20
> >   325 0012 8076      		andi r24,lo8(96)
> >   326 0014 31F0      		breq .L5
> >    *** /* do stuff */
> >   338                   .L5
> 
> 
> 
> And here we see the problem with the bit numbers: they're not connected 
> with the register.
> 
> I made the mistake of referring to UCSR0B, when TXC0 and UDRE0 are 
> actually in UCSR0A.
> 
> This is a not-uncommon error using this idiom. You don't have the 
> ability to make this error when using bitfields.
> 
> The above should be:
> 
>          if (UCSR0A & ((1 << bitTXC0) | (1 << bitUDRE0)))
>             /* do stuff */
> 
> 
> I spent some time making a safer version using C++ templates, but 
> haven't been satisifed with its ease of use.
> 
> -- 
> Ned Konz
> ned@...
> http://bike-nomad.com
>