From owner-freebsd-hackers  Thu Sep 30  9:51:46 1999
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Date: Thu, 30 Sep 1999 11:46:30 -0400
To: W Gerald Hicks <wghicks@bellsouth.net>
From: Dennis <dennis@etinc.com>
Subject: Re: A bug in the sppp driver? 
Cc: freebsd-hackers@FreeBSD.ORG
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References: <Your message of "Wed, 29 Sep 1999 17:25:15 BST."             <038d01bf0a97$3652f8d0$2e00a8c0@nt46daniel>
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At 05:54 AM 9/30/99 -0400, W Gerald Hicks wrote:
>
>> doing state machines with switch statements is a big mess.
>
>Still, you'll find a lot of them around.  Do you have a favored
>technique for coding complex state machines?  (I'm a collector :)


yes, state tables. Clean and easy to modify.

>
>One scheme I've been using for quite some time is to use a function
>pointer as a 'state variable', sometimes making a stack of them for
>a more flexible machine.
>
>Sometimes I use a transition matrix for selection of the 'state function'
>but more often the functions themselves perform 'next state' selection.

then your back to switch statements, because you have actions that are used
in multiple states.

event=decode_event(cur_state,pdata);
do_action(cur_state[event][action]);
new_state=cur_state[event][newstate];


Dennis






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