【正文】
x y cin sum cout 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 0 0 2 0 1 1 0 1 1 1 0 1 0 1 3 1 1 1 1 1 輸出信號 sum和 cout的值與輸入信號中“ 1”的數(shù)目有關(guān) 表 31邏輯功能表 ENTITY five_ports_circuit IS PORT (x,y,cin: IN BIT; sum,cout: OUT BIT); END five_ports_circuit; ARCHITECTOR behavioral_view OF five_ports_circuit IS BEGIN PROCESS VARIABLE n : INTEGER; CONSTANT sum_vector : BIT_VECTOR(0 TO 3) : =“0101”; CONSTANT carry_vector : BIT_VECTOR(0 TO 3) : =“0011”; BEGIN WAIT ON x, y,cin; n : =0; IF x =’1’ THEN n : =n+1; END IF; IF y =’1’ THEN n : =n+1; END IF; IF cin =’1’ THEN n : =n+1; END IF; sum =sum_vector (n) ; cout =