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Re: [lwip-users] sys_timeout

From: Peter Graf
Subject: Re: [lwip-users] sys_timeout
Date: Wed, 08 Mar 2006 09:46:47 +0100
User-agent: Mozilla Thunderbird 1.0 (Windows/20041206)

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

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 

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.


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