Lpc2000

Hi,

I'm trying to do some DSP algorithms on my ARM7TDMI, therefore I'm
aiming for the maximum performace that I can get from this chip.
The code is optimized for the usage of almost all avalible registers
and to spare unnecessary loads and stores. At the begining I tried
writing it in C, but I got a lot of STR LDR commands that slowed down
the process.

For the time being I'm just learning the ARM architecture, though I
would like (in the future) to use it for some heavy calculations.

Thanks in advance,
MB

--- In lpc2000@yahoogroups.com, "Bryce Schober" <bryce.schober@...> wrote:
>
> Robert's point is a good one. Aviod inline assembler where possible.
I've
> often found that GCC's optimization was better than I would've come
up with
> anyway. I've only used inline assembly in a few cases where I needed the
> absolute best performance, which involved using instructions that it was
> hard to get GCC to emit. It seems that you're using a pseudo-opcode that
> might not even be recognized by the GCC compiler. Regarding inline
assembly
> syntax in general, it seems that you're missing some syntax concepts
that
> can be found here:
> 
> http://www.ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html#s2
> 
> Then, if you really need to get in deep you can check out your GCC
version's
> manual section entitled "Constraints for asm operands", which will
also have
> target-specific bits. But again, as recommended by Robert, stay away
from
> inline assembly, unless absolutely
>
necessary.<http://gcc.gnu.org/onlinedocs/gcc-4.0.1/gcc/Constraints.html#Constraints>
> 
> On 5/7/06, Robert Adsett <subscriptions@...> wrote:
> >
> > At 11:15 AM 5/6/2006 +0000, MB wrote:
> > >I'm trying to use C variables inside inline assembly code, but can't
> > >get it to work (the compiler is gcc).
> > >
> > >static const short g_psMyArray asm("g_psAsmMyArray:") =
> > >{ 1, 2, 3, 4};
> > >
> > >void myfunc()
> > >{
> > >     asm("ADRL  r14, psAsmMyArray");
> > >}
> > >
> > >This results with an error (something like "symbol is undefined in
> > >current file").
> >
> > Why not just use C?  What's the advantage you are expecting that's
> > compelling you to use assembly?
> >
> > If you can provide a little more detail maybe we can solve the
problem in
> > another way.
> >
> > 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
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> >
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> 
> --
> Bryce Schober
> 
> 
> [Non-text portions of this message have been removed]
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