Lpc2000

Robert,
      Can you elaborate on how this is used?  Right now the statement:

dummy = U0IIR;	// clear the flag

Is optimized out in my UART ISR.

Richard

-- In lpc2000@yahoogroups.com, Robert Adsett <subscriptions@a...> wrote:
> At 11:55 PM 1/24/05 +0000, you wrote:
> >      I don't follow, the registers are declared thusly:
> >
> >#define SPI_SPDR   (*((volatile unsigned char *) 0xE0020008))
> 
> 
> Sigh, It would probably help if I wrote what I was thinking.  I meant 
> volatile when I wrote void.
> 
> Given the above, then the following line
> 
>   (void)SPI_SPDR;
> 
> should generate a read of the register (and discard the result)
regardless 
> of the level of optimization.  volatile tells the compiler that it must 
> generate an access and not optimize it out.  If it does not then
compiler 
> has a bug.  You should probably write a short 2 or 3 line program to 
> demonstrate it and report it.
> 
> Of course optimizers are notoriously buggy so turning down the
optimization 
> level to get correct code is not terribly unusual.  I seem to recall an 
> instance or two where a minimum optimization was required in order to 
> generate correct code but that's rather less common.
> 
> Robert
> 
> " 'Freedom' has no meaning of itself.  There are always restrictions,
> be they legal, genetic, or physical.  If you don't believe me, try to
> chew a radio signal. "
> 
>                          Kelvin Throop, III