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Mail Archives: djgpp/1997/02/01/00:07:31

To: djgpp AT delorie DOT com
Subject: Re: fixed point math: NEED HELP QUICK!
Message-ID: <19970131.205344.8463.0.chambersb@juno.com>
References: <5clmjm$ee3 AT nr1 DOT toronto DOT istar DOT net>
<WWX+eCAORA8yEwz6 AT foobar DOT co DOT uk>
From: chambersb AT juno DOT com (Benjamin D Chambers)
Date: Fri, 31 Jan 1997 23:52:33 EST

On Thu, 30 Jan 1997 02:15:42 +0000 Paul Shirley
<Paul AT foobar DOT co DOT uk DOT chocolat> writes:
>In article <199701290130 DOT UAA02417 AT delorie DOT com>, DJ Delorie
><dj AT delorie DOT com> writes
>>
>>> function.  Anyway, here's my problem;  To my understanding the 
>following
>>> are 100% equal:
>>> 
>>> other_stuff = stuff / 256;
>>> other_stuff = stuff << 8;
>>
>>The second multiplies.  Try ">> 8" instead.
>>
>
>And if other_stuff is signed, >>8 and /256 aren't identical either.
>(which might save you some debugging later ;)
Actually they are.  If it's signed, then I've noticed gcc shifts in the
sign bit (with sal instead of shl).

...Chambers

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