How to Reverse the Bit Order of a Byte: The Simplest Method?

Reversing Bit Order in a Byte: Discovering the Simplest Method

For developers seeking a straightforward approach to reversing the bit order of a byte, there are various techniques. However, identifying the simplest one requires a closer examination.

The objective is to transform bit sequences like these:

• 1110 -> 0111
• 0010 -> 0100

Let's explore the solution provided in the response:

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;
}

This code utilizes a series of bitwise operations to achieve the reversal. Initially, the left four bits are swapped with the right four bits using:

b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;

Next, adjacent bit pairs are swapped with:

b = (b & 0xCC) >> 2 | (b & 0x33) << 2;

Finally, adjacent single bits are swapped with:

b = (b & 0xAA) >> 1 | (b & 0x55) << 1;

This sequence of operations ultimately reverses the bit order within the byte, making this solution the simplest and most straightforward for developers to implement.

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