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From: barrett@jhunix.HCF.JHU.EDU (Dan Barrett)
Newsgroups: comp.sys.amiga.programmer
Subject: SCMD_SETPARAMS problem -- catch-22?
Message-ID: <7649@jhunix.HCF.JHU.EDU>
Date: 26 Feb 91 04:51:46 GMT
Distribution: usa
Organization: The Johns Hopkins University - HCF
Lines: 39


	I have written a MIDI program that opens the serial port in
shared mode.  I would like to allow this program to be run multiple
times simultaneously.  The program can be used for reading or writing
MIDI, but not both.  (Which is why I want multiple copies to be run.)

	However, the SCMD_SETPARAMS command (to set baud rate, etc.)
will fail if another process has any pending reads on the serial port.
This is a problem if I try to run several copies of my program!  The
SCMD_SETPARAMS fails on the invocation of the second copy.

	So here's the question.  How can I have a program that is watching
the serial port for reads, and still start up a second program that needs
to execute SCMD_SETPARAMS?  Or is there another way to accomplish what
SCMD_SETPARAMS does?  I am doing this:

	Midi->io_SerFlags               = SERF_RAD_BOOGIE;
        Midi->io_Baud                   = MIDI_BAUD_RATE;
        Midi->io_ExtFlags               = 0;
        Midi->IOSer.io_Command          = SDCMD_SETPARAMS;

        if (DoIO((struct IORequest *)Midi) != 0)
		Error(...);

Of course I don't want two different trying to read the serial port at
once.  But I would like to have a "reader" and "writer" program existing
simultaneously.  The only way I can do it now is to run the "writer" 
program first (no pending writes) and then the "reader".  I don't want to
be forced to run these programs in any particular order.

	Thanks for any advice.

                                                        Dan

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