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This program shows a logic of swapping the most significant bit with the least significant bit, second most significant bit with the second least significant bit, and so on.

/*
* swap_bits.c  -   Swap corresponding bits
*/

/*
*  This program swaps the corresponding bits of a character.  For example,
*          msb (bit 7) is exchanged with lsb (bit 0);
*          msb-1 (bit 6) is exchanged with lsb+a (bit 1), so on
*/

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>

unsigned char
swap_bits ( unsigned char uc )
{
    unsigned char bits = 0;
    int times = CHAR_BIT / 2,
          msb = CHAR_BIT-1,
          lsb = 0;

     while ( times– )
     {
        bits |= ( (uc & (1<<msb)) >> msb ) << lsb;
        bits |= ( (uc & (1<<lsb)) >> lsb ) << msb;
        msb–;
        lsb++;
     }
         
    return bits;
}

int
main ( void )
{
    unsigned char uc = 0xef;

    printf ( "The byte: %#x\n", uc );
    printf ( "After bit swapping: %#x\n", swap_bits ( uc ) );
    return EXIT_SUCCESS;
}

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Related Blog Items

• Swapping nodes in a single linked list
• Bit swapping - Style II
• What do I need to know when mixing C and C++ code?
• Swapping variables without additional space
• Sorting A Linked List with Bubble Sort

This entry was written by Vijay Zanvar and posted on February 6, 2007 at 4:01 pm and filed under Algorithms, Bits & Bytes Manipulation. Bookmark the permalink. Follow any comments here with the RSS feed for this post. Post a comment or leave a trackback: Trackback URL.