module code_2_audio(clk,indata,douki,outdata);

input clk;
input [7:0] indata;
input douki;
output [15:0] outdata;

reg shift_douki;

reg [9:0] sub_index;
reg [9:0] index;

reg [15:0] pre_outdata;
reg [15:0] outdata;

always@(posedge clk)begin
	shift_douki <= douki;
end


always@(posedge clk)begin
	if(shift_douki==0 && douki==1)
		sub_index <= 0;
	else if(sub_index == 767) //256*2-1
		sub_index <= 0;
	else
		sub_index <= sub_index + 1'b1;
end


always@(posedge clk)begin
	if(shift_douki==0 && douki==1)
		index <= 0;
	else if(sub_index == 767 && index!=200)
		index <= index + 1'b1;	
	else
		index <= index;	
end

// index=:0  sub_index:602+258   -> tokushu_code  -I
// index=:1  sub_index:93   -> tokushu_code  -I 


always@(posedge clk)begin
	if(index==0 && sub_index==100)begin
		pre_outdata <= pre_outdata ;	
	end
	else if(index==1 && sub_index==100)begin
		pre_outdata<= pre_outdata;	
	end	
	else if(index[0]==0 && sub_index==100)begin
		pre_outdata[7:0] <= indata;
		pre_outdata[15:8] <= pre_outdata[15:8];		
	end
	else if(index[0]==1 && sub_index==100)begin
		pre_outdata[7:0] <= pre_outdata[7:0];	
		pre_outdata[15:8] <= indata;
	end
	else
		pre_outdata <= pre_outdata;	
end


always@(posedge clk)begin
	if(index[0]==1 && sub_index==101)
		outdata <= pre_outdata;	
	else
		outdata <= outdata;	
end


endmodule