ch3-Case

2019-10-24

unique,unique0 case

​ All case statements can be qualified by unique or unique0 keywords to perform violation checks like we saw in if-else-if construct.

​ unique and unique0 ensure that there is no overlapping case items and hence can be evaluated in parallel. If there are overlapping case items, then a violation is reported.

• If more than one case item is found to match the given expression, then a violation is reported and the first matching expression is executed
• If no case item is found to match the given expression, then a violation is reported only for unqiue

unique0 does not report a violation if no items match the expression

priority case

类似priority if，如果匹配到零个分支，报错；匹配到第一个分支就退出。

module tb;
  bit [1:0] 	abc;
  
  initial begin
    abc = 0;
    
    // First match is executed
    priority case (abc)
      0 : $display ("Found to be 0");
      0 : $display ("Again found to be 0");
      2 : $display ("Found to be 2");
    endcase
  end
endmodule

Simulation Log

ncsim> run
Found to be 0
ncsim: *W,RNQUIE: Simulation is complete.