On Wed, Jan 11, 2006 at 03:01:28PM +0100, Alfons Adriaensen wrote:
> On Wed, Jan 11, 2006 at 01:53:25PM +0000, Steve Harris wrote:
>
> > I agree about ARM assembly, I have written some (not DSP related) many
> > years ago and it was quite straightforward.
>
> Another ex Acorn user ???
Damn, does it show ;)
> > Does this ARM chip have real fixedpoint hardware, or do you have to do bit
> > manipulations to get the numbers?
>
> It doesn't have anything specific fixed point. It's all integer, and you,
> as the programmer, have to imagine a binary point somewhere in your data
> and keep track of it.
Yeah, some of my LADPSA code uses pseudo-fixedpoint to track things like
phases. I found it slightly simpler than floating point, and things like
modulos and finding what quadrant its in is really cheap.
> What helps enormously on the ARM is that all arithmetic instructions can
> include a (no overhead) shift on one of the operands. There are some
> other unique things, such as the 16 conditions on *all* instructions.
I see, that is helpful. I imagine that coding things like IIR filters is
still quite time consuming though. I would expect that you need to switch
between different point positions a lot.
- Steve
Received on Wed Jan 11 16:15:11 2006
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