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Path: utzoo!mnetor!seismo!rochester!cornell!batcomputer!dyon
From: dyon@batcomputer.TN.CORNELL.EDU (Dyon Anniballi)
Newsgroups: net.micro.amiga
Subject: Sending multiple chars out serial port
Message-ID: <915@batcomputer.TN.CORNELL.EDU>
Date: Wed, 20-Aug-86 22:37:59 EDT
Article-I.D.: batcompu.915
Posted: Wed Aug 20 22:37:59 1986
Date-Received: Thu, 21-Aug-86 04:45:13 EDT
Reply-To: dyon@batcomputer.UUCP (Dyon Anniballi)
Organization: Theory Center, Cornell University, Ithaca NY
Lines: 45

From dyon Wed Aug 20 22:35:49 EDT 1986


(sorry if you are getting this twice, but I think it didn't make it out the
first time)

   Hello again,
As readers here might have noticed, we (hsgj and I) have detected some
"irregularities" with the Amiga Kernel while writing our applications.

This time, the trouble is with writing to the serial port.  First, for
your enjoyment, some code right from the RKM:

WriteSer(io,data,length)
struct IOExtSer *io;
char *data;
int length;
{
	io->IOSer.io_Data = (APTR)data;		/* Abridged version */
	io->IOSer.io_Length = length;		/* to speed typing */
	io->IOSer.io_Command = CMD_WRITE;
	return(DoIO(io));
}

Ok, this function works perfectly if "length = 1", ie if you are only
writing one character out the port.  However, if we are writing a
known length string out the port, say "char data[5] = {'h','e','l','l','o'} "
and we give data = &data[0] and length = 5, then we get maybe the
first two characters received by the serial listener fine, but the rest
is random garbage chars.  By the way, this occurs at Baud rates as slow
as 300, and with parity, stop bits, write bits identical on both ends
of the serial port.  At first I thought it was overwriting an output
buffer, but I guess "data" points to the output buffer.  So we can't
figure out why we can't send the string.
   Our temporary solution has been to do a for loop and just send each
individual char out with length = 1; this works fine.  But this is
not very nice at high bauds, so if anyone has any clues as to our 
problem, it would be appreciated.
   Note that this symptom appeared in Workbench v1.1.  We upgraded to
V1.2 beta 4 recently, but the problem still persists.

Thanks much, 
-- JR
UUCP: ihnp4!cornell!batcomputer!dyon
ARPA: dyon%batcomputer@cu-arpa.ccs.cornell.edu