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Path: utzoo!utgpu!water!watnot!watmath!clyde!cbatt!ucbvax!ajs@EDDIE.MIT.EDU@procase.UUCP
From: ajs@EDDIE.MIT.EDU@procase.UUCP
Newsgroups: comp.windows.x
Subject: Apollo Bug
Message-ID: <8702270007.AA00078@procase.UUCP>
Date: Thu, 26-Feb-87 19:07:18 EST
Article-I.D.: procase.8702270007.AA00078
Posted: Thu Feb 26 19:07:18 1987
Date-Received: Sat, 28-Feb-87 08:07:20 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 34

Problem:
    On an SR9.2.3 Apollo, xterm will drop characters during character
    insertion.

To reproduce:
    Go into GNUemacs, or any editor which inserts characters with
    `\E[@X' (where X is the char to insert).  Start inserting text.
    At some point the character under the cursor will disappear.
    Doing a xrefresh will not cause the character to reappear.

The Bug:
    bzero(3) is the culprit.  Xterm uses this routine to clear out
    the screen buffer's new character space.  The problem is that
    for certain alignments of the character pointer and small values
    of the count, count + 1 bytes will be zeroed.

The Fix:
    I don't know if this is fixed in SR9.5 (I am trying to find out
    now.)  What I've done in the meantime is to insert the following
    routine into xterm:

	bzero( ptr, cnt )
	register char *ptr;
	register int cnt;
	{
	    while( cnt-- > 0 ) *(ptr++) = '\0';
	    return 0;
	}

Andrew Jay Schneider

UUCP:	...{hplabs, tektronix, ihnp4!amdcad}!cae780!procase!ajs
ARPA:	decwrl!cae780!procase!ajs@berkeley or
	leadsv!cae780!procase!ajs@lll-lcc  (both untested)