On 03/03/2013 04:22 AM, David Rowe wrote: > Hello Samuel, > > Actually there are $3 32-bit microprocessors with floating point, and > many embedded processors (e.g. those used in android phones) no have > FPUs. So I think the need for fixed point is diminishing, its only a > few thousand more transistors on a chip, Moores law etc. > > A year ago I worked up an estimate for the labour reqd for a fixed point > port - it was about $80k. > > Cheers, > > David > The M4 is really making floating point hardware widely available in modest prices MCUs. Look at how many M4 based MCUs actually have an M4F core. Its more than a few thousand transistors, though.Its 10's of thousands. Still, its a tiny part of a typical MCU die.
A fixed point version of a DSP algorithm will typically take around half the energy of a floating point implementation on the same generation of silicon. That is often a good argument for a fixed point version in low power applications. I'm not sure how applicable that might be for codec2. It depends what it is used for. In most wireless applications the energy for the wireless channel should dominate. You'll never achieve predictable bit exactness without fixed point, and some people love bit exact implementations of algorithms. There really aren't any good arguments for their existence, though. Easy conformance testing is a pretty weak argument. Having a fixed point implementation so you can use a dsPIC, or other small DSP seems a negative argument for most people. In most cases you would need to add the cost of the dsPIC to a system that already has a processor capable of doing the work in floating point. :-) Devices like the dsPIC are struggling to survive. Their only real hope is applications like digitally controlled power supplies. ARMs are pushing them out of most motor control applications, which had looked like a good market for them until recently. Regards, Steve ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_feb _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
