Re: [lwip-users] sys_timeout

[Peter Graf]

Hi Curt,

> I see what you and Derek are getting at, with sys_timeout being used only by 
> lwip and i/f threads.  But I still fail to see why it
> should be in src/core instead of cleanly separated, and implemented this way 
> especially if it results in inelegant code and common
> misunderstandings.

As long as one uses the given interfaces, and doesn't deal with the 
internals, there is little misunderstanding here. I would not propose a 
re-structuring of the code because there is little benefit and a risk of 
breaking essentials, especially the common usage of lwIP for both 
multitasking and RAW API.

> Suppose I want to implement timeouts using a hardware timer interrupt?  Or 
> suppose I want them to be handled by a separate thread?
> Or suppose I want to implement them as a setitimer and SIGALRM?  I'm out of 
> luck?

You just don't implement the timeouts, you implement "semaphores with 
timeout" as required by lwIP. This is the given interface for a 
multitasking O/S, and nobody keeps you from implementing them with 
whatever means you like.

> I'm actually not using tcpip_thread() or any of the src/api, but rather the 
> "raw" API (I'm precluded from using netconn since its
> message passing is based on shared memory).  My O/S also does not have 
> semaphores.  It has nothing but timer interrupts, network
> interface interrupts, and bus interrupts.  I define NO_SYS.

From your previous postings, e.g. about semaphores, I concluded that 
you intend to use the multitasking API. The RAW API is a totally 
different issue.

Peter