70. Universal Barrel Shifter

Shift/rotate an 8-bit word by a variable amount (0–7). Supports logical left/right, arithmetic right, rotate left/right, and pass-through.

Requirements

• Module: univ_barrel8
• Inputs: x[7:0], sh[2:0], mode[2:0]
• Outputs: y[7:0]
• Keep it fully combinational (no clocks, no delays).

Behavior

• Inputs: x[7:0], sh[2:0], mode[2:0]
• Output: y[7:0]
• Modes (unsigned unless noted):
  • 3'b000 → PASS
  • 3'b001 → LSL (logical left)
  • 3'b010 → LSR (logical right)
  • 3'b011 → ASR (arithmetic right, sign-extend)
  • 3'b100 → ROL (rotate left)
  • 3'b101 → ROR (rotate right)
  • 3'b110/111 → reserved (treat as PASS in reference)