Sender:	crough45 AT amc DOT de
Date:	Mon, 14 Apr 1997 09:03:44 +0100
From:	Chris Croughton <crough45 AT amc DOT de>
Mime-Version:	1.0
To:	fighteer AT cs DOT com
Cc:	djgpp AT delorie DOT com
Subject:	Re: Help! Random is not working right
Message-Id:	<97Apr14.100108gmt+0100.21894@internet01.amc.de>

John M. Aldrich wrote:

>It should also be noted that gcc is very smart when it comes to
>optimizations, and will probably convert modulus operators into masks
>when you're modding with powers of two.  It's okay to trust the
>compiler!  ;)

This has been true with all recent compilers I've used (Borland,
Microsoft and a couple of Unix ones).  They seem to do that piece
of optimisation even with optimisation turned off.  The same for
multiplication and division by constant powers of 2.  I find it
clearer to write:

  lsb = word % 256;
  msb = word / 256;

than the equivalent lowlevel operations:

  lsb = word & 0xFF;
  msb = word >> 8;

(assuming that 'word' is unsigned short, of course, for clarity).
I've never had a speed or size penalty because of it...

Chris

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