Float32Full Question

jagrifen

Does anyone know what happens when multiple cogs make use of one instance of Float32Full at the same time? I guess I am asking if Float32Full has any collision avoidance built in? Any good suggestions on dealing with this other than calling two instances of Float32Full (which would require two cogs)? I've also considered switching to F32. Does that work any better?
Thanks for your help.

Mike Green

None of the floating point objects have any locking built in to prevent problems with use from several cogs at once. You're responsible for doing that. It's generally left out because it adds a small amount of overhead, both in terms of execution time and memory, but more if it's added in a generalized way, and it's rarely needed. The Propeller Manual shows how to use the various LOCKxxx calls in Spin, but the details of how and where to put the calls depends on what your program is doing and how the cogs interact.

jagrifen

Thanks, Mike. That's what I figured. I guess it's time I got around to learning how to use the LOCK commands.

jagrifen

So I think I understand the Lockset and Lockclr commands but I am a little unclear on the locknew command. Assuming I am only going to create one lock and I have multiple cogs and one instance of Float32Full, would it be correct to just say something like

VAR byte SemID

PUB Initialize
SemID := Locknew

Mike Green

Yes.

The primary reason to have LOCKNEW at all is that you might use library objects which use a lock internally and you don't necessarily know which one or even if it does or not. Using LOCKNEW, the hardware keeps track of which locks are in use so you don't have to do it.

Duane Degn

Float32Full is so last decade.

Try Lonesock's F32.

It's drop-in compatible, only uses one cog and is faster than Float32Full. It also keeps the inside of your Propeller chip clean.

Duane