Lpc2000

Charles, I know you have said this before, but I disagree, IF the bit
fields are supplied by the compiler vendor.  Both IAR and KEIL provide
bit field definitions for the Philips parts' registers.

 

While they occasionally use different names, that is rare (e.g. IOSET1
vs. IO1SET) and is easily fixed with a define.  So they take
responsibility for endian-ness and making sure the bits line up.

 

 

Using bit fields makes the code much more readable than constants like
0x00040000.  You can use notation like #define regbit (1<<18), but that
is not as clear as IO0SET_bit.P0.18.  (did I do the shift right - err
left - correctly to get bit 18? Is the constant 0x00040000 correct for
bit 18?).... 

 

We used to hear the same things about writing in c - real programmers
write in assembler.  Now it is real programmers don't use bit fields.  

 

Bit fields are a tool.  Know how to use the tool and it can save time.
Even if I had to redefine the bit field defines to move to another
compiler, I think it is worth it.

 

My two cents.

 

Dan

 

 

  _____  

From: lpc2000@yahoogroups.com [mailto:lpc2000@yahoogroups.com] On Behalf
Of Charles Manning
Sent: Wednesday, November 09, 2005 10:13 AM
To: lpc2000@yahoogroups.com
Subject: Re: [lpc2000] Bit-fields are brain-dead (was Looking to buy
compiler)

 


> Just to add to the 'never use bit-fields advice', here's an article
> I found a while ago (where the author calls bit-fields brain-dead) ...

I would refine this:

Never use them for anything that does hardware accesses or has hardware 
dependencies.

I use them quite a bit for packing data into software structures because
this 
allows me to do bit-wise packing without writing a whole bunch of
shifter 
code. Being able to bit-pack structures easily can save a lot of space
when 
creating large numbers of them.






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