Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!ECNCDC.BITNET!UUCJEFF
From: UUCJEFF@ECNCDC.BITNET
Newsgroups: comp.sys.atari.st
Subject: Midi problem revisted
Message-ID: <8806151931.AA05945@ucbvax.Berkeley.EDU>
Date: 15 Jun 88 19:27:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 18

A few weeks ago a reader had a problem with outputing several midi bytes.
I think he was trying to use the Xbtimer.  I have later found out courtesy
of Stefan Daystrom of Hybrid Arts that you cannot have any TOS, BIOS, or
XBIOS calls inside an interrupt.  You have to do whatever it is you want without
the calls, this is due to the re-entrancy characteristics of the ST.
Therefore, you cannot use Bconstat or Midiws from inside and Xbtimer interrupt.

I was having the same problem, I was thinking it might have been the stack
size, but replaced it with the same code that the system call would have done,
(modifying it to fit the routine) and it works perfectly.  I even save
time by avoiding all the stack bookkeeping by the subroutine call.
I got the code of those system calls from Abacus, you can also get them
from the developer's kit.

While this fact problem was explained somewhere in the docs, it would
have been nice if they would have mentioned this in the docs of the
Xbtimer call.

Jeff, UUCJEFF@ECNCDC.BITNET