Verilog equivalent operator

Equivalent operator

Equivalence operators include logical equality （==）, Logical inequality （!=）, Congruence （===）, Non congruent （!==）.

The normal results of an equivalent operator are 2 Kind of ： It's true （1） Or false （0）.

Logical equality / The inequality operator cannot compare x or z, When the operand contains a x or z, Then the result is an uncertain value .

Congruent comparison , If the bitwise comparison has the same x or z, The return result can also be 1, That is, congruent comparison can be compared x or z. therefore , The result of congruent comparison must not include x. Examples are as follows ：

example

A = 4 ;
B = 8'h04 ;
C = 4'bxxxx ;
D = 4'hx ;
A == B        // It's true
A == (B + 1)  // For false
A == C        // by X, Not sure
A === C       // For false , The return value is 0
C === D       // It's true , The return value is 1