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
