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From: roger@everexn.com (Roger House)
Newsgroups: comp.lang.c
Subject: Re: Help!!!!
Message-ID: <1990Sep21.182142.9013@everexn.com>
Date: 21 Sep 90 18:21:42 GMT
References: <26f8528c.35c1@uop.uop.edu>
Organization: Everex Systems, Inc.
Lines: 27

In <26f8528c.35c1@uop.uop.edu> acs17111@uop.edu (hamid misnan) writes:

>Hai,
>	Can someone help me in how can I swap bit 2 and 5, I had tried
>	to use bitwise, but I cannot finger it out how it will work.
>	Any help will be appreciated.
>	Thanks in advance.

The possible transformations are these:

		543210
		----------------------
		0xx0xx  ->  no change
		0xx1xx  ->  1xx0xx
		1xx0xx  ->  0xx1xx
		1xx1xx  ->  no change

Say B is the variable for which bits 2 and 5 are to be swapped.  Then this 
code will do the trick, although it requires the use of another variable, 
t:

	if ((t = B & 0x24) && t != 0x24)      /* Swap bits 2 and 5 of B */
		B ^= 0x24;

There are probably better ways to do it.

						Roger House