题解 |

`timescale 1ns/1ns
module encoder_83(
   input      [7:0]       I   ,
   input                  EI  ,
   
   output wire [2:0]      Y   ,
   output wire            GS  ,
   output wire            EO    
);
assign Y[2] = EI & (I[7] | I[6] | I[5] | I[4]);
assign Y[1] = EI & (I[7] | I[6] | ~I[5]&~I[4]&I[3] | ~I[5]&~I[4]&I[2]);
assign Y[0] = EI & (I[7] | ~I[6]&I[5] | ~I[6]&~I[4]&I[3] | ~I[6]&~I[4]&~I[2]&I[1]);

assign EO = EI&~I[7]&~I[6]&~I[5]&~I[4]&~I[3]&~I[2]&~I[1]&~I[0];

assign GS = EI&(I[7] | I[6] | I[5] | I[4] | I[3] | I[2] | I[1] | I[0]);
//assign GS = EI&(| I);
         
endmodule

module encoder_164(
   input      [15:0]      A   ,
   input                  EI  ,
   
   output wire [3:0]      L   ,
   output wire            GS  ,
   output wire            EO    
);

wire     [1:0]       EO_TEMP     ;
wire     [2:0]       Y_TOP       ;
wire     [2:0]       Y_BOTTOM    ;
wire     [1:0]       GS_TEMP     ;
reg     [3:0]       Y_TEMP      ;
//reg                 choose      ;


encoder_83 u_top(
    .I(A[15:8]),
    .EI(EI),
    .Y(Y_TOP),
    .GS(GS_TEMP[1]),
    .EO(EO_TEMP[1])
);

encoder_83 u_bottom(
    .I(A[7:0]),
    .EI(EO_TEMP[1]),
    .Y(Y_BOTTOM),
    .GS(GS_TEMP[0]),
    .EO(EO_TEMP[0])
);

always@(*)begin
    // choose  =    EO_TEMP[1] |   EI      ;
    case ({GS_TEMP[1],EO_TEMP[1]})
        2'b00:Y_TEMP   =   4'b0000           ;
        2'b01:Y_TEMP   =   {1'b0,Y_BOTTOM}   ;
        2'b10:Y_TEMP   =   {1'b1,Y_TOP}      ;
        default: Y_TEMP =   4'b0000       ;
    endcase
end

assign  L   =   Y_TEMP      ;
assign  EO  =   EO_TEMP[1]  &   EO_TEMP[0]  ;
assign  GS  =   EI  &   (GS_TEMP[1] |   GS_TEMP[0]) ;
endmodule

注意case等号左边的比特位描述