From:	dontmailme AT iname DOT com (Steamer)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Right shift
Date:	Fri, 12 May 2000 14:43:46 GMT
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References:	<391C0409 DOT 79567772 AT tiscalinet DOT it>
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night DOT walker AT tiscalinet DOT it wrote:

>Why right-shifting ">>" a negative signed int will first turn it
>positive?
>
>4 >>1 = 2 but also -4 >> 1 = 2!!

I don't see how you get 2.  I get -2.

But you shouldn't right-shift negative numbers anyway if you want your
code to be portable, because the results are implementation-defined.

>What EXACTLY happens?

In the case of DJGPP, the compiler uses the SAR instruction.  This fills
the vacated bits with copies of the sign bit.

S.

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