[SV]SystemVerilog Unique if

                               SystemVerilog Unique if

   Unique if evaluates all the conditions parallel.

   In the following conditions simulator issue a run time error/warning,

• More than one condition is true
• No condition is true or final if doesn’t have corresponding else

一、Unique if example’s

       In the below example,More than one condition is true.value of a=10, b=20 and c=40. conditions a<b and a<c are true, Therefore on execution, simulator issue a run time warning.“RT Warning: More than one condition match in ‘unique if’ statement.”

module unique_if;
  //variables declaration
  int a,b,c;
 
   initial begin
     //initialization
     a=10;
     b=20;
     c=40;
 
     unique if ( a < b ) $display("\t a is less than b");
     else   if ( a < c ) $display("\t a is less than c");
     else                $display("\t a is greater than b and c");
  end
endmodule

Simulator Output

a is less than b
RT Warning: More than one conditions match in 'unique if' statement.

二、Unique if example 2

       In below example,No condition is true and final if doesn’t have corresponding else.value of a=50, b=20 and c=40, conditions a<b and a<c are false,Therefore on execution, simulator issue a run time warning.“RT Warning: No condition matches in ‘unique if’ statement.”

module unique_if;
  //variables declaration
  int a,b,c;
 
   initial begin
     //initialization
     a=50;
     b=20;
     c=40;
    
     unique if ( a < b ) $display("\t a is less than b");
     else   if ( a < c ) $display("\t a is less than c");
  end
     
endmodule

Simulator Output

RT Warning: No condition matches in 'unique if' statement

三、Unique if example 3

       In below example, value of a=50, b=20 and c=40.conditions a<b and a<c are false, so else part is true, there is no simulator run time warning.

module unique_if;
 
  //variables declaration
  int a,b,c;
 
   initial begin
     //initialization
     a=50;
     b=20;
     c=40;
    
     priority if ( a < b ) $display("\t a is less than b");
     else     if ( a < c ) $display("\t a is less than c");
     else                  $display("\t a is greater than b and c");
  end
    
endmodule

Simulator Output

a is greater than b and c