54. Population Count

Design a combinational module that counts how many bits in an 8-bit input are 1. Use a synthesizable for loop (constant bounds).

Requirements

• Module: popcount8
• Inputs: in[7:0]
• Outputs: count[3:0] (range 0–8)
• Implement in one always @* using a for loop and an integer loop variable.
• Provide a default/initialization for count inside the block (avoid latches).
• No delays/timing controls in the design.

Behavior

• in = 8'b0000_0000 → count = 0
• in = 8'b1111_1111 → count = 8
• Works for any 8-bit input.