[lwip-users] Re: [lwip] Patch for PaulOS + crash fixes

[psheer]

> 
> All of the above already is true for lwIP (this has been discussed a few 
> times the last months), but perhaps I have been bad at pointing this out. 
> Anyway, this is basically how it works:

ok, thanks

this clears things up quite a bit

i think my original email and your reply should DEFINATELY
go into the docs! :-)

best

-paul

> 
> * To get a simple TCP/IP stack without any thread support, etc., only compile 
> the files in the core/ directory. 
> * To get a multithreaded TCP/IP stack with a sequential API, also include the 
> files in api/ in your project.
> * When running in a single-threaded environment, the sys_arch implementation 
> is really simple - look at src/arch/6502/sys_c64.c for an example of this.
> * In a single threaded environment, the functions ip_input(), tcp_fasttmr() 
> and tcp_slowtmr() is the interface to lwIP. ip_input() should be called when 
> incoming packets arrive, and tcp_fasttmr() and tcp_slowtmr() should be called 
> periodically. The periodical TCP timers are taken care of in the api/tcpip.c 
> file (for multithreaded systems).
> 
> Also, the sample project in proj/unixsim/ should not be taken as the 
> definitive model for how to use lwIP; it is mostly meant as one specific 
> example of how to build lwIP. 
> 
> Of course, this does not mean that there is room for improvement: The TCP 
> timer interface should be made simpler. I just added a new TCP function, 
> tcp_tmr(), which should be called every 100 ms. This function takes care of 
> dispatching the actual TCP fast and slow timers. The old tcp_slowtmr() and 
> tcp_fasttmr() are also avaliable, since people may depend on them.
> 
> Also, your comment about being able to turn of the sys.c layer is very 
> relevant. Single threaded environments does not need the sys.c code, so the 
> sys_ declarations could be replaced with null #defines and sys.c would not be 
> compiled into the project.
> 
> I've also cleaned up the makefile stuff for the unixsim example project. 
> Perhaps a new example project, a non-os project, should be added as well?
> 
> >   *- you should be able to plug in your own malloc module
> >         so that you can use GNU malloc.c if you have it, or
> >         whatever malloc implementation your OS supports.
> >         the patch i sent you has #ifdef's around all the
> >         memory allocation stuff.
> 
> This was something I was thinking about in the early stages of lwIP 
> development, before the memp stuff was included. This should be implemented 
> by #defining macros for mem_malloc() et al. in mem.h instead of using lots of 
> #ifdefs in the code. I've added this to my todo list.
> 
> /adam
> -- 
> Adam Dunkels <address@hidden>
> http://www.sics.se/~adam
> [This message was sent through the lwip discussion list.]


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