//CircuitA ze schematu
module Circuit_zad_4(input [3:0] a, b,
input cin,
output reg [3:0] out);
always@*
begin
out = (a + b + cin) % 10;
end
endmodule
//Multiplekser
module mux21 (

    input x,y,s,
    output m
);
assign m = (~s & x) | (s & y);
endmodule


//Moduł odpowiedzialny za dodawanie
module adder_BCD_2_digits_zad5(input [3:0] a, b,
input cin,
output [3:0]s0,
output reg [3:0]s1,
output reg err1, err2);
wire[3:0] out_a, x;
reg[3:0] z, temp;
always @*
begin
s1 = 0;
err1 = 0;
err2 = 0;
if (a > 9)
err1 = 1;
if(b > 9)
err2 = 2;
else
begin
temp = a + b + cin;
if (temp > 9)
begin
z = 1;
s1 = 1;
end
else
begin
z = 0;
s1 = 0;
end
end
end
Circuit_zad_4 ex(a, b, cin, out_a);
mux214 ex2(temp, out_a, z[0], x);
assign s0 = x;
endmodule
//Główny na plytke
module symulacja_zad_4(
input [8:0]SW,
output [0:6]HEX0, HEX1, HEX3, HEX5,
output [9:0]LEDR);
wire [3:0] out1, out2;
assign LEDR[7:0] = SW[7:0];
adder_BCD_2_digits_zad5(SW[3:0], SW[7:4], SW[8], out1, out2, LEDR[8], LEDR[9]);
decoder_hex_10 ex2(out2, HEX1);
decoder_hex_10 ex3(out1, HEX0);
decoder_hex_10 ex4(SW[7:4], HEX5);
decoder_hex_10 ex5(SW[3:0], HEX3);
endmodule