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From: ado@elsie.UUCP (Arthur David Olson)
Newsgroups: net.lang.c
Subject: Re: reversing a mask
Message-ID: <4082@elsie.UUCP>
Date: Sat, 24-Nov-84 19:03:27 EST
Article-I.D.: elsie.4082
Posted: Sat Nov 24 19:03:27 1984
Date-Received: Mon, 26-Nov-84 02:00:40 EST
References: <1@imd.UUCP> <469@ncoast.UUCP> <691@gloria.UUCP>
Organization: NIH-LEC, Bethesda, MD
Lines: 24

[Usenet brand software--ask for it by name]

> What's the fastest way to reverse a 16-bit mask in C?  In 68000 asl?
> (Maybe this should be in net.puzzle!)

Nah. . .too easy:

static int revtab[65536] = {
	0x0000, 0x8000, 0x4000, 0xc000,

	/* . . .16,382 lines of code left out to keep net costs down. . . */

	0x3fff, 0xbfff, 0x7fff, 0xffff
};

#define reverse(value)	(revtab[(unsigned int) value])

. . .with suitable documentation about range and type of the parameter being the
responsibility of the caller. :-)
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