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From: raymond@math.berkeley.edu (Raymond Chen)
Newsgroups: comp.lang.c
Subject: Re: binary constants (??)
Keywords: macro, constant, binary
Message-ID: <1989Nov18.205735.11004@agate.berkeley.edu>
Date: 18 Nov 89 20:57:35 GMT
Article-I.D.: agate.1989Nov18.205735.11004
References: <305@frf.omron.co.jp> <602@chem.ucsd.EDU>
Sender: usenet@agate.berkeley.edu (USENET Administrator;;;;ZU44)
Reply-To: raymond@math.berkeley.edu (Raymond Chen)
Organization: U.C. Berkeley
Lines: 43
In-reply-to: tps@chem.ucsd.edu (Tom Stockfisch)

/* Disgusting macro alert! */

#define BIT1(x) (0 x
#define BIT2(x) ((0 x
#define BIT3(x) (((0 x
/*  ...  */
#define BIT6(x) ((((((0 x

#define O *2)
#define I *2 + 1)

main()
{
printf("%x",  BIT6(I O I O I O));   /* the 6-bit number 101010 */
}

----- alternately -----

#define OOOO *16)
#define OOOI *16+1)
#define OOIO *16+2)
/* ... */
#define IIII *16+15)

#define BIT4(x) (0 x
#define BIT8(x) ((0 x
/* ... */
#define BIT16(x) ((((0 x

main()
{
printf("%x", BIT16(OOOO OIOI IOIO OIIO)); /* the 16-bit number
						0000 0101 1010 0110 */
}

/* Disclaimer:  I don't use this!  I just wrote it to see if it 
		could be done.  It would be curious to compare this
		against the original poster's macro which
		approaches the problem from a different angle. 
*/

Raymond Chen (mathematician by training, hacker by choice)
			raymond@math.berkeley.edu