module vending_machine (BTNL,BTNC,BTNR,BTNU,BTND,switch_0,switch_1,switch_2,LED0,LED1,LED2,Seg3,Seg2,Seg1,Seg0,clock);

input switch_0,switch_1,switch_2;
input clock;
input BTNU; //reset
input BTNL,BTNC,BTNR,BTND;

output LED0;
output LED1;
output LED2;

output [0:6] Seg3;
output [0:6] Seg2;
output [0:6] Seg1;
output [0:6] Seg0;

wire [2:0] fund;
wire [2:0] refund;
wire [1:0] mesg;

reg [7:0] segment_input_0;
reg [7:0] segment_input_1;
reg [7:0] segment_input_2;
reg [7:0] segment_input_3;

wire flag_coin,flag_pur;

fund_maintenance m1(switch_1,switch_0,switch_2, BTNU, clock, fund,flag_coin);
Purchase_Selection m2(BTNL,BTNC,BTNR,BTND, BTNU, clock, fund,refund,mesg,flag_coin,flag_pur);
coin_return m3(LED0,LED1,LED2, clock,BTNU,refund,flag_coin,flag_pur);

seven_segment m4(segment_input_0,Seg0);
seven_segment m5(segment_input_1,Seg1);
seven_segment m6(segment_input_2,Seg2);
seven_segment m7(segment_input_3,Seg3);

always @*
begin

case (fund)

3'b110 : //30
begin
segment_input_3 = 8'b00000011;
segment_input_2 = 8'b00000000;
end

3'b101 : //25
begin
segment_input_3 = 8'b00000010;
segment_input_2 = 8'b00000101;
end

3'b100 : //20
begin
segment_input_3 = 8'b00000010;
segment_input_2 = 8'b00000000;
end

3'b011 : //15
begin
segment_input_3 = 8'b00000001;
segment_input_2 = 8'b00000101;
end

3'b010 : //10
begin
segment_input_3 = 8'b00000001;
segment_input_2 = 8'b00000000;
end

One is faced with a decision to purchase parts from three suppliers...