Sender: nate AT cartsys DOT com
Message-ID: <35BD6187.A151342E@cartsys.com>
Date: Mon, 27 Jul 1998 22:28:39 -0700
From: Nate Eldredge <nate AT cartsys DOT com>
MIME-Version: 1.0
To: "Salvador Eduardo Tropea (SET)" <salvador AT inti DOT gov DOT ar>
CC: EDWARD CASHIN <cashin AT pollux DOT cs DOT uga DOT edu>, djgpp AT delorie DOT com
Subject: Re: implementation of modulo operator in djgpp
References: <m0z0rEP-000S4rC AT inti DOT gov DOT ar>
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Salvador Eduardo Tropea (SET) wrote:
> 
> EDWARD CASHIN <cashin AT pollux DOT cs DOT uga DOT edu> wrote:

> > ...which begs the question, "How fast is the modulo?"
> > and more specifically, how is it implemented?
> 
> Modulo is just the rest of a division. So if last is a variable (not a macro
> and not a constant) you'll get a div or idiv and that's sllloooowwww.
> But I think you must call gcc with -S to take a look at the generated
> assembler ;-)

True.  Suggested optimization:

Make the buffer size a power of 2.  Then do:

front = (front + 1) & (size - 1);
-- 

Nate Eldredge
nate AT cartsys DOT com