Path: utzoo!attcan!uunet!cbmvax!andy
From: andy@cbmvax.UUCP (Andy Finkel)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Could somebody tell me ...
Message-ID: <5519@cbmvax.UUCP>
Date: 16 Dec 88 18:10:46 GMT
References: <8812151937.AA17954@postgres.Berkeley.EDU>
Reply-To: andy@cbmvax.UUCP (Andy Finkel)
Organization: Commodore Technology, West Chester, PA
Lines: 48

In article <8812151937.AA17954@postgres.Berkeley.EDU> dillon@POSTGRES.BERKELEY.EDU (Matt Dillon) writes:
>	Now, who can figure out what I am talking about here?  The idea is
>for the initial call from main() to *create* a light weight process context

Hmmm....sounds like coroutines

>for the subroutine and to then allow main() to continue and call other
>lwp's to create them.  Thus, a direct call to task1() or task2() must return
>	startlwp() allocates a copy of the stack accessable to the subroutine.
>Specifically, M+N bytes are allocated where M is the number of bytes already

yup, we're talking coroutines here.
>	Not bad, eh?  So, why would you want to do this when the amiga has
>multitasking?  Because this allows you to modularize your code without
>the overhead of a task for each module!  The context switch is much faster
>than with real tasks.
>
>	But the real reason is to get out of the main-loop driven standard
>of programming (mac users are fond of quoting the fact that multitasking
>does not avoid the need for a main-event-wait-loop).  Here, one would

>	So, I need ideas on the waiting part (that waits for some even and
>does the context switching).  We need something that nicely complements
>Wait(), but in the lwp sense.

we call it cowait()

You are well underway to reinventing coroutines, Matt :-)

What are coroutines ?  Well, they are pretty much as Matt is on
the way to describing them...lightweight processes that operate
synchroniously, using your stack.  The Amiga file system uses
them extensively.  They are a pretty clever idea.  They are also
found in Workbench.  I think Neil Katin was sufficiently impressed
with the concept that he used that model of programming internal
to Workbench.
>					-Matt


-- 
andy finkel		{uunet|rutgers|amiga}!cbmvax!andy
Commodore-Amiga, Inc.

"Possibly this is a new usage of the word 'compatible' with which
 I was previously unfamiliar"

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