Article View: comp.sys.amiga.tech
Article #9604Re: Need info on exceptions
From: Ronald G Minnich
Date: Fri, 26 Aug 1988 15:06
Date: Fri, 26 Aug 1988 15:06
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2453 bytes
>In article <632@super.ORG> rminnich@metropolis.UUCP (Ronald G Minnich) writes:
>>How about (let's be gross now)
^^^^^^^^^^^^^^^^^^
And I Meant Gross- Get It?
You know, one gets the feeling that one's messages are not
being read well. What would Miss Manners think?
Look, those of you that haven't, take a look at any
available amiga device driver. What you will begin to see
is that the amiga rom kernel is built around the idea of your
basic message-passing model. But what is passed in the messages?
data structures with pointers in them! An idea central to the Amiga
is that an address in any tasks address space is not a virtual
address but a physical memory address. That means that you can hand
a pointer off to another task and it will be valid in THAT tasks's address
space. There is a nice term for this- which i have just forgotten,
damn it- but the Sprite machine being built at Berkeley uses this idea.
It is nice.
The point is, yes on Unix to get state information out of a
process you really need to use signal(). On the amiga, there
are better ways to do it, that involve standard mechanisms
(e.g. PutMsg or something else), that result in a much nicer
design. And the basic heart of the nicer design is the fact that you
can share memory easily. You don't need to do mmap() or some other
ugly thing.
And yes, of course, if you have more than one variable you start
to get into the need for semaphores. Guess what. The amiga has
very nice Semaphore calls that work! So USE THEM. Big Deal.
My main point is that we should not take a problem-solving
methodology that applies to Unix and drop it right onto the
Amiga. There are in many cases ways to do things on the Amiga
that are BETTER than their counterparts on Unix. USE THEM.
Two-message-long-flame-off.
ron
Technical Details
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!batcomputer!itsgw!steinmetz!uunet!super!rminnich From: rminnich@super.ORG (Ronald G Minnich) Newsgroups: comp.sys.amiga.tech Subject: Re: Need info on exceptions Message-ID: <658@super.ORG> Date: 26 Aug 88 15:06:19 GMT References: <4989@pasteur.Berkeley.EDU> <566@wuphys.UUCP> <1754@munsell.UUCP> <413@brambo.UUCP> <632@super.ORG> <414@brambo.UUCP> Sender: uucp@super.ORG Reply-To: rminnich@metropolis.UUCP (Ronald G Minnich) Organization: Supercomputing Research Center, Lanham, MD Lines: 33