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Date: January 08, 1988 09:54
From: KIM::ALBAUGH
To: @SYS$MAIL:ENGINEER
The following Greenhills C bug (version 1.8.0) caused a really obscure bug in the stats package on XYBots. I have kluged around it on all the stats packages I "control", but those of you who are winging it on your own, or just generally multiplying unsigned shorts occasionally, should watch out! The following code fragment: unsigned int coins,time; ... time = (unsigned short)time * 60; produced the following assembly: MOVEQ #0,D0 MOVE.W D3,D0 *fr MULS #60,D0 note that it "knew" that D0 was unsigned, and that the constant 60 (which is clearly positive) would fit in a short, but it used a MULS. Changing the second line to: time = (unsigned short)time * (unsigned short)60; fixes the problem (this time).
Jan 08, 1988