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Q120FreeSystemVerilog

Clear the lowest set bit

Difficulty
Easy
Topic
Bit Manipulation
Language
SV
Interview prompt

Question

Return x with its least-significant 1 bit cleared.

Candidate starting point

Implementation scaffold

function automatic int unsigned clear_lowest_one(int unsigned x);
  // TODO: implement.
endfunction
Reviewed example

Trace one case

Input
value = 8'b1011_0000
Expected output
8'b1010_0000

ANDing with value - 1 clears only the lowest set bit, which is bit 4 here.

What to cover

Requirements

  1. Return zero when x is zero.
  2. Use one arithmetic and one bitwise operation.
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