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From: angst@cs.ucsb.edu (Hopelessly in love w/Donna Reed)
Newsgroups: comp.lang.c
Subject: Bit Masking Question
Message-ID: <12191@hub.ucsb.edu>
Date: 23 Jun 91 07:50:18 GMT
Sender: news@hub.ucsb.edu
Reply-To: angst@cs.ucsb.edu (Hopelessly in love w/Donna Reed)
Organization: Funf auf def nach oben offenen Richterskala
Lines: 43

This is not necessarily a C question, but since I'm programming it C,
I can ask in that context.

What I'm doing is reading characters from a file and I'd like to 
categorise the characters into 3 groups based on their 2 most-
significant bits.  Group 1 has '11' in their MSb's, group 2 has
'10' in their MSb's, and group 3 has '0X' (X = don't care) in
their MSb's.

Here's how I'm currently doing it:

    #define FMASK   0xC0
    #define RMASK   0x80

    int c;
    ...
	    switch (c & FMASK) {
		case FMASK:
		    Do stuff for group 1
		    ...

		case REPMASK:
		    Do stuff for group 2
		    ...
	    
		case 0x0:
		case 0x40:
		    Do stuff for group 3
		    ...

		default:
		    fprintf (stderr, "bad news!\n");
	    }

This seems to work, but I'd like comments.  Is there a better way to
do this?  Should I make #define's for 0x0 and 0x40?  Is there a way
to #define bits?o

Thanks in advance for any help!

"Let the fools have their tartar sauce."	|          Dave Stein
  		        - Mr. Burns		|       angst@cs.ucsb.edu
						|    angst%cs@ucsbuxa.bitnet