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From: earleh@eleazar.dartmouth.edu (Earle R. Horton)
Newsgroups: comp.sys.mac.programmer
Subject: "TN.248.DAs in Need of Time" in need of proofreader.
Keywords: Sloppy, careless, wrong.
Message-ID: <15462@dartvax.Dartmouth.EDU>
Date: 7 Sep 89 21:40:30 GMT
Sender: news@dartvax.Dartmouth.EDU
Reply-To: earleh@eleazar.dartmouth.edu (Earle R. Horton)
Organization: Thayer School of Engineering
Lines: 38

The topic is setting flags in the high-order byte of a desk
accessory's Device Control Entry.  The quoted text is from Technote
248, August 1989 version.

>The _BitClr and _BitSet Toolbox utilities are a mite on the
>brain-damaged side...
>
>(I think whoever wrote these routines did this just to see if anyone
>was paying attention.)
>
>Pascal
>
>BitClr(@dce^.dCtlFlags, 31 - dNeedTime);{ clear bit 5/dNeedTime bit. IM I-471 }
>BitSet(@dce^.dCtlFlags, 31 - dNeedTime);{ set bit 5/dNeedTime bit.  IM I-471 }
>
>C
>
>dce->dCtlFlags ^= dNeedTime;		/* clear bit 5/dNeedTime bit */
>dce->dCtlFlags |= dNeedTime;		/* set bit 5/dNeedTime bit */
>

The Pascal code is incorrect.  Substitute 7 for 31.  Look who's paying
attention now!

The C code is grossly incorrect.  The correct code is

dce->dCtlFlags &= ~(1 << (dNeedTime + 8) ); /* Clear. */
dce->dCtlFlags |= (1 << (dNeedTime + 8));   /* Set.   */

Furthermore, "dNeedTime" is not defined in the MPW C header files.
This leads me to believe that the C code, and possibly the Pascal
code, has never been tested or even typed in anywhere, except for the
Technote.

Tip 1:	Test code before distribution.
Tip 2:	Know your operators.

Earle R. Horton