Re: ldrb vs ldrh in gcc-3.4.4 (ARM)

[Steven Scholz <steven dot scholz at imc-berlin dot de>]

Richard,

> > > First google hit on "AT91RM9200":
> > > 	http://www.atmel.com/dyn/products/product_card.asp?part_id=2983
> > >
> > > That page mentions that it's an ARM920T core.  First google hit on
> > > "ARM920T":
> > > 	http://www.arm.com/products/CPUs/ARM920T.html
> > >
> > > That page mentions 'ARMv4T'.
> >
> > Thanks for googling for me! ;-)
> >
> > So I use either -march=armv4 _OR_ -mcpu=arm920t. Right?
> >
> > (Using both brought me a warning about conflicting).
>
>
> the arm920t is an armv4t device (the 't' is thumb).
>
> Basically, there are two options, -march=xxx and -mtune=xxx that are
> independent (one selects the available instructions, the other the best
> way to use that set for the intended cpu).  -mcpu=xxx is shorthand that
> can be used to set both options in one go: so -mcpu=xxx is equivalent to
> writing -march=<arch_of(xxx)> -mtune=xxx.
>
> Note that to get Thumb code you have to use -mthumb; it's not sufficient
> to tell the compiler that you have thumb instructions available.

Thanks a million. Maybe you could explain the difference of arm920t and arm9tdmi 
as well, please?

--
Steven

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