What is a barrel shifter and how is it implemented?

A barrel shifter performs multi-bit shifts in a single clock cycle, unlike iterative shifters that shift one bit per cycle. Implementation uses layers of multiplexers: for n-bit data, log2(n) mux stages shift by powers of 2. Each stage either passes data through or shifts by its power value based on shift amount bits. For 8-bit shifter: first stage shifts 0 or 1, second 0 or 2, third 0 or 4. Barrel shifters support logical/arithmetic shifts and rotations, essential in ALUs and DSP applications for fast bit manipulation.