🚀 go-pugleaf

In <1992Dec23.212321.26522@ryn.mro4.dec.com> pjdm@chmeee.enet.dec.com (Peter Mayne) writes:


>In article <id.CG2W.R8A@ferranti.com>, peter@ferranti.com (peter da silva) writes:

>>That's right. The UNIX programming model. The point is that the UNIX API is
>>very high level, and can be modified to provide any capability I've ever
>>heard of without breaking it. There is NO excuse for any new operating
>>system after about 1984 or 85 to use anything lower level. It increases the
>>cost of software design, increases the cost of education and training, and
>>decreases the amount of commonly available high quality software.

>OK, try this. VMS has something called an AST (Asynchronous System Trap) which
>is similar to a user-mode interrupt. This may occur at any time: for instance,
>an asynchronous I/O can call an AST routine when the I/O completes. When the
>AST routine completes, control returns to the code that was executing at the
>time the AST occurred. (The analogy in NT is the APC, or Asynchronous
>Procedure Call.)

>Now, much of the run-time stuff in UNIX is non-reentrant. In particular, the 
>use of errno springs to mind. If the AST (or APC) was introduced into the
>UNIX model, how can I use these non-reentrant routines safely in an AST
>routine without screwing things up?

Use the right Unix.  Concurrent (formerly Masscomp) RTU provides
user-level AST's, reentrant (and preemptable) run-time stuff in UNIX
kernal routines, without any problem.  Much of the device-driver
libraries for asynchronous devices (data acquisition, programmable
graphics system, vector processor, etc.) is written with AST's.  The
model for the user is a more sophisticated signal interface.
(Masscomp was started by people from DEC, I recently learned.)

>Peter Mayne                     | My statements, not Digital's.
>Digital Equipment Corporation   |
>Canberra, ACT, Australia        | "AXP!": Bill the Cat

David B. Chorlian
Neurodynamics Lab
SUNY/HSCB 
davidc@panix.com

-- 
David B. Chorlian
Neurodynamics Lab
SUNY/HSCB 
davidc@panix.com