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testingverilogbusicarus

How to test if a 3-bit bus has the first bit set on 1 - verilog

I'm trying to find out how could I check if a 3-bit bus has the msb set on 1, i.e. 1xx. When I check bus==3'b1xx nothing seems to happen.

Solution

  • The result of the expression you wrote can only be (1'b0) or (1'bx), which are both considered false for an if statement branch.

    Assuming you declared the bus as wire [2:0] bus; you can check it using bus[2] == 1'b1

    Now in SystemVerilog, you can do a wildcard match using bus ==? 3'b1xx which treats the RHS X's as don't cares. X's on the LHS are treated the same as ==.