Gatesv

You are given a four-bit input vector in[3:0]. We want to know some relationships between each bit and its neighbour:

• out_both: Each bit of this output vector should indicate whether both the corresponding input bit and its neighbour to the left (higher index) are '1'. For example, out_both[2] should indicate if in[2] and in[3] are both 1. Since in[3] has no neighbour to the left, the answer is obvious so we don't need to know out_both[3].

• out_any: Each bit of this output vector should indicate whether any of the corresponding input bit and its neighbour to the right are '1'. For example, out_any[2] should indicate if either in[2] or in[1] are 1. Since in[0] has no neighbour to the right, the answer is obvious so we don't need to know out_any[0].

• out_different: Each bit of this output vector should indicate whether the corresponding input bit is different from its neighbour to the left. For example, out_different[2] should indicate if in[2] is different from in[3]. For this part, treat the vector as wrapping around, so in[3]'s neighbour to the left is in[0].

hint

The both, any, and different outputs use two-input AND, OR, and XOR operations, respectively. Using vectors, this can be done in 3 assign statements.

solution

module top_module( 
    input [3:0] in,
    output [2:0] out_both,
    output [3:1] out_any,
    output [3:0] out_different );
	
    assign out_different[3] = in[3] ^ in[0];
    always @(*) begin
        for (integer i=0;i<3;i++) begin
            out_both[i] = in[i] & in[i+1];
        end
        for (integer i=1;i<4;i++) begin
            out_any[i] = in[i] | in[i-1];
        end
        for (integer i=0;i<3;i++) begin
            out_different[i] = in[i] ^ in[i+1];
        end
    end
    
endmodule