  I really don't understand how the polling should work, so that
stuff if probably incorrect.  Look for comments containing XXXPOLL

  I don't know what the argument to midiintr is supposed to be
either.  I'm hoping it is a dev_t, but that's probably unlikely.
Look for a comment containing XXXINTR.

  This driver should verify any pids set in the TIOCSPGRP ioctl.
If it doesn't verify them at the ioctl stage, the driver will
just go ahead and try to kill whatever you set.  This could be
any process at all (like init for example).  A potential security
hole I think.  Look for the XXXSIGNAL comments.

  For better timing accuracy, I now use long longs when converting
to/from smf ticks and kernel ticks.  I don't know if the default
SVR4 compiler supports long longs.  I know GCC does.  But, if you
use GCC, you'll probably need to link in special math functions.
These are called __divdi3, __muldi3 etc.  I've included the ones
that are needed in quad.c and quad.h.  These files are the versions
used with Linux.  They'll probably need to be modified to work with
SVR4.  Look in the BSD directory to see what the unmodified files
look like.
  I also don't know how to modify the makefile to compile multiple
files.  You'll have to do figure it out on your own.
