Re: [lwip-users] use of static variables in tcp_in.c

[Jonathan Larmour]

Goldschmidt Simon wrote:
> I think it would be a good thing moving from global variables to
> parameters,
> but I remember adam writing about intentionally using global variables
> as a design goal in embedded systems (using a smaller stack, favouring
> statically configured memory) which is an opinion I don't share, but we
> would
> have to discuss that!

I think Adam made a good design choice. The stack is designed to be 
single-threaded so what's the point doing otherwise. I would add, though, 
that it's not just a question of stack space (although that's a good enough 
reason on its own), but also code space and performance - marshalling all 
the various arguments into the right position for function calls would take 
extra code and time. It would also add to register pressure.

Incidentally there are other ways to deal with different priority of 
operations depending on the thread priority of the threads using the stack.

Jifl
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