Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!mcsun!ukc!axion!tigger!raph
From: raph@tigger.planet.bt.co.uk (Raphael Mankin)
Newsgroups: comp.lang.c
Subject: Re^2: Coroutines in C
Message-ID: <555@tigger.planet.bt.co.uk>
Date: 12 Sep 89 11:12:38 GMT
References: <214@castle.ed.ac.uk> <5899@ficc.uu.net> <10861@smoke.BRL.MIL> <5914@ficc.uu.net>
Organization: RT5111, BTRL, Martlesham Heath, England
Lines: 20

peter@ficc.uu.net (Peter da Silva) writes:

>In article <10861@smoke.BRL.MIL>, gwyn@smoke.BRL.MIL (Doug Gwyn) writes:
>> In article <5899@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes:
>> >If [simple setjmp] is used, it should be possible to create
>> >a fake stack frame and register set in a jmp_buf and tranfer control to it
>> >using longjmp.

>> You need separate (non-overlapping) stacks, not just a stack frame.
>> Otherwise the coroutines will step on each other's <DELETED>.

Provided you setjmp/longjmp saves tnd restores he full stack pointer
(MSDOS users beware here) it is quite possible to write coroutines in C.
I have in fact written a full multi-tasking supervisor (coroutines
with frills) entirely in C. This runs under MSC and the only kludge is
two lines of assembly code to do the initial stack-frame setup for new
tasks.
-- 
Raphael Mankin
raph@planet.bt.co.uk