二、Verilog Language

Vectors 

1、Vectors

Problem Statement：

Build a circuit that has one 3-bit input, then outputs the same vector, and also splits it into three separate 1-bit outputs. Connect output o0 to the input vector's position 0，o1 to position 1, etc.

module top_module ( 
    input wire [2:0] vec,
    
    output wire [2:0] outv,
    output wire o2,
    output wire o1,
    output wire o0  
); 
    assign outv = vec;
    assign o2 = outv[2];
    assign o1 = outv[1];
    assign o0 = outv[0];

endmodule

2、Vectors in more details

Problem Statement： 

 Build a combinational circuit that splits an input half-word (16 bits, [15:0] ) into lower [7:0] and upper [15:8] bytes.

`default_nettype none     // Disable implicit nets. Reduces some types of bugs.
module top_module( 
    input wire [15:0] in,
    output wire [7:0] out_hi,
    output wire [7:0] out_lo 
);
    assign out_hi = in[15:8];
    assign out_lo = in[7:0] ;

endmodule

 3、Vector part select

Problem Statement： 

A 32-bit vector can be viewed as containing 4 bytes (bits [31:24], [23:16], etc.). 

Build a circuit that will reverse the byte ordering of the 4-byte word.

module top_module( 
    input  [31:0] in,
    output [31:0] out 
);
    assign out[31:24] = in[7:0];
    assign out[23:16] = in[15:8];
    assign out[15:8]  = in[23:16];
    assign out[7:0]   = in[31:24];


endmodule

4、Bitwise operators

Problem Statement： 

 Build a circuit that has two 3-bit inputs that computes the bitwise-OR of the two vectors, the logical-OR of the two vectors, and the inverse (NOT) of both vectors. Place the inverse of b in the upper half of out_not (i.e., bits [5:3]), and the inverse of a in the lower half.

module top_module( 
    input [2:0] a,
    input [2:0] b,
    
    output [2:0] out_or_bitwise,
    output out_or_logical,
    output [5:0] out_not
);
    assign out_or_bitwise = a | b;
    assign out_or_logical = a || b;
    assign out_not = ~{b,a};

endmodule

 5、Four-input gates

Problem Statement： 

Build a combinational circuit with four inputs, in[3:0].

There are 3 outputs:

• out_and: output of a 4-input AND gate.
• out_or: output of a 4-input OR gate.
• out_xor: output of a 4-input XOR gate.

module top_module( 
    input [3:0] in,
    output out_and,
    output out_or,
    output out_xor
);
    assign out_and = & in[3:0];
    assign out_or  = | in[3:0];
    assign out_xor = ^ in[3:0];

endmodule