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From: hamilton@uiucuxc.CSO.UIUC.EDU
Newsgroups: net.micro.amiga
Subject: Re: input from the serial port...
Message-ID: <148600016@uiucuxc>
Date: Fri, 15-Nov-85 11:22:00 EST
Article-I.D.: uiucuxc.148600016
Posted: Fri Nov 15 11:22:00 1985
Date-Received: Sat, 16-Nov-85 21:02:59 EST
References: <400@caip.RUTGERS.EDU>
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Nf-ID: #R:caip.RUTGERS.EDU:400:uiucuxc:148600016:000:1678
Nf-From: uiucuxc.CSO.UIUC.EDU!hamilton    Nov 15 10:22:00 1985


>> 	I have a friend who is trying to get input from the serial
>> 	port.  He has been able to send characters, but not recieve
>> 	them.  Any ideas?
>	Yes if he is using the C compiler... "LATTICE" then he should
>	be advised that there is a bug with the data element of the
>	SERIO->IOSer.io_Data.  This element must be at least 4 bytes
>	(a long) and the data (ie the character received from the
>	serial port) will be in the HI byte of the DATA element.  

io_Data is a pointer to a buffer, not a buffer itself.  the real bug,
as was posted recently (for which, much thanx!) involves the C compiler.
io_Data is declared an APTR, which is defined:
typedef STRPTR		*APTR;		/* absolute memory pointer */
typedef unsigned char	*STRPTR;	/* string pointer */
(should be "typedef unsigned char *APTR" or "typedef STRPTR APTR"?)
now, if you have in your program:
	char buf[BUFSIZE];
	...
	xxx.io_Data = (APTR) &buf[0];
it is possible for the value in io_Data to be, eg, &buf[-3], due to
the lattice C bug that truncates some low-order bits.  there are several
ways to work around this bug: obtain your buffer from malloc, manually
align your buffer pointer, or pass your buffer pointer to a function where
the formal argument is declared APTR (eliminate the "conversion").
    i have a prototype terminal emulator program working that reads
from the serial port.  i'll post it when i've cleaned it up some and
added file transfer capability.

	wayne hamilton
	U of Il and US Army Corps of Engineers CERL
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