【HDLbits答案】Circuits-Combinational Logic（其一）

因为目录Circuits-Combinational Logic下的练习题有点多，我还没做完，今天先发Basic Gates与Multiplexers下的。

Basic Gates

in_out

module top_module (
    input in,
    output out);
assign out = in ;
endmodule

Exams/m2014 q4i

module top_module (
    output out);
assign out = 1'b0;
endmodule

Exams/m2014 q4e

module top_module (
    input in1,
    input in2,
    output out);
assign out = ~(in1|in2);
endmodule

Exams/m2014 q4f

module top_module (
    input in1,
    input in2,
    output out);
assign out = (~in2)&in1;
endmodule

Exams/m2014 q4g

module top_module (
    input in1,
    input in2,
    input in3,
    output out);
 assign out = (~(in1^in2))^in3;
endmodule

Gates

module top_module( 
    input a, b,
    output out_and,
    output out_or,
    output out_xor,
    output out_nand,
    output out_nor,
    output out_xnor,
    output out_anotb
);
assign out_and     =a&b;
assign out_or   =a|b;
assign out_xor  =a^b;
assign out_nand    =~(a&b);
assign out_nor  =~(a|b);
assign out_xnor =~(a^b);
assign out_anotb=a&~b;    

endmodule

7420

module top_module ( 
    input p1a, p1b, p1c, p1d,
    output p1y,
    input p2a, p2b, p2c, p2d,
    output p2y );
assign p1y = ~(p1a&p1b&p1c&p1d);
assign p2y = ~(p2a&p2b&p2c&p2d);
endmodule

Truthtable1

module top_module( 
    input x3,
    input x2,
    input x1,  
    output f   
);

assign f = ( ~x3 & x2 & ~x1 ) | 
             ( ~x3 & x2 & x1 ) |
             ( x3 & ~x2 & x1 ) |
             ( x3 & x2 & x1 ) ;

endmodule

Mt2015 eq2

module top_module ( input [1:0] A, input [1:0] B, output z ); 
    assign z=(A==B)?1'b1:1'b0;
endmodule

Mt2015 q4a

module top_module (input x, input y, output z);
    assign z = (x^y) & x;
endmodule

Mt2015 q4b

module top_module ( input x, input y, output z );
    assign z=~(x^y);
endmodule

Mt2015 q4

module top_module (input x, input y, output z);
wire z13,z24;
wire zor,zand;
assign z13 = (x^y) & x;
assign z24 = ~(x^y);
assign zor = z13|z24;
assign zand =z13&z24;
assign z =zor ^zand;
endmodule

Ringer

module top_module (
    input ring,
    input vibrate_mode,
    output ringer,       
    output motor         
);
assign ringer = ring & ~vibrate_mode;
assign motor = ring & vibrate_mode;

endmodule

Thermostat

module top_module (
    input too_cold,
    input too_hot,
    input mode,
    input fan_on,
    output heater,
    output aircon,
    output fan
); 
assign heater = mode & too_cold;
assign aircon = ~mode & too_hot;
assign fan = heater|aircon|fan_on;
endmodule

Popcount3

module top_module( 
    input [2:0] in,
    output [1:0] out );
assign out[0] = (~in[2] & ~in[1] & in[0]) | (~in[2] & in[1] & ~in[0]) | (in[2] & ~in[1] & ~in[0]) | (in[2] & in[1] & in[0]);
assign out[1] = (in[1] & in[0]) | (in[2] & in[0]) | (in[2] & in[1]);
endmodule

Gatesv

module top_module( 
    input [3:0] in,
    output [2:0] out_both,
    output [3:1] out_any,
    output [3:0] out_different );
assign out_both = in[3:1] & in[2:0];
assign out_any  = in[3:1] | in[2:0];
assign out_different = {in[0], in[3:1]} ^ in;
endmodule

Gatesv100

module top_module( 
    input [99:0] in,
    output [98:0] out_both,
    output [99:1] out_any,
    output [99:0] out_different );
assign out_both = in[99:1] & in[98:0];
assign out_any  = in[99:1] | in[98:0];
assign out_different = {in[0], in[99:1]} ^ in;
endmodule

Multiplexers

Mux2to1

module top_module( 
    input a, b, sel,
    output out ); 
assign out = (sel)? b:a;
endmodule

Mux2to1v

module top_module( 
    input a, b, sel,
    output out ); 
assign out = (sel)? b:a;
endmodule

Mux9to1v

module top_module( 
    input [15:0] a, b, c, d, e, f, g, h, i,
    input [3:0] sel,
    output [15:0] out );
always @(*)begin 
    case(sel)
    4'd0:out = a ;
    4'd1:out = b ;
    4'd2:out = c ;
    4'd3:out = d ;
    4'd4:out = e ;
    4'd5:out = f ;
    4'd6:out = g ;
    4'd7:out = h ;
    4'd8:out = i ;
    
    default:out = 16'hffff;
    endcase 
end 
endmodule

Mux256to1

module top_module( 
    input [255:0] in,
    input [7:0] sel,
    output out );
    assign out = in[sel];
endmodule

Mux256to1v

module top_module( 
    input [1023:0] in,
    input [7:0] sel,
    output [3:0] out );
    assign out = in[sel*4+:4];
endmodule