On Sat, Aug 05, 2006 at 02:04:42AM +0100, Richard Earnshaw wrote:
> > 
> > volatile ushort ptr = /* WHATEVER THE DEVICE ADDRESS is MAPPED to */
> > ushort value;
> > 
> > *ptr = value; /* If you want to store to the device */
> > value = *ptr; /* If you want to read from it. */
> > 
> > The problem is that the compiler generates two byte operations for
> > such a reference, rather than one half word operation, for V4.
> 
> Nonsense. ARMv4 has half-word operations and if you use -march=armv4 the 
> compiler will use them.

But, IIRC, that range of offsets is less for the half-word operations,
and gcc is likely to use 32bit operations to read 16bit values (masking
the high bits).  Even using misaligned transfers for 4n+2 addresses.
(or do we disable that in netbsd's versions of gcc?)

	David

-- 
David Laight: david@l8s.co.uk