Xref: utzoo comp.os.msdos.programmer:747 comp.sys.ibm.pc.misc:1374
Path: utzoo!attcan!uunet!unisoft!bdt!doug
From: doug@bdt.UUCP (Doug Asherman)
Newsgroups: comp.os.msdos.programmer,comp.sys.ibm.pc.misc
Subject: TASM bug?
Message-ID: <4691@bdt.UUCP>
Date: 3 Sep 90 03:02:16 GMT
Distribution: na
Organization: Beckemeyer Development Tools
Lines: 34

I've run into something in TASM that may be a bug, but I'm not
sure.  The code in question looks somewhat like this (compressed
for brevity's sake):

cseg	segment
	assume etc. etc.
; data
__key__		db 	?
; other data
; code
; get the time from dos
; move the seconds into key
	mov	__key__,dl	; dl contains the seconds
;....stuff deleted
; ....then later on
	mov	ax,word ptr __key__

....I took this through the debugger a few times and ax always ended up
as some weird number like 7f1b, or something equally strange.

I was able to get around this by doing the following:

	mov	al,__key__
	cbw	; sign-extend __key__

Though I'm hardly an assembly language guru, it's always been my
understanding that casting a byte variable to a word will sign-
extend it automatically.  I haven't had a chance to see if MASM
behaves the same, so I can't say if MASM does the same thing.

If this is a bug, though, Borland should probably know about it.

-- 
.signature: permission denied