How to Reverse Bit Order in a Byte with Simple Bit Shifting and Logical Operations?

Reverse Bit Order in a Byte with Ease

In the realm of bit manipulation, reversing the order of bits in a byte is a common task. While various approaches exist, this article explores the simplest method to implement.

To understand the concept, consider the following bit reversal examples:

• 1110 reverses to 0111
• 0010 reverses to 0100

Implementation:

The presented solution utilizes bit shifting and logical operations to achieve bit reversal:

unsigned char reverse(unsigned char b) {
   b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
   b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
   b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
   return b;
}

Explanation:

• The first step isolates the left four bits and exchanges them with the right four bits.
• The second step swaps adjacent pairs of bits.
• The final step swaps adjacent single bits.

These operations effectively reverse the order of bits, resulting in the desired output, where the original leftmost bit becomes the rightmost, and vice versa.

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