[求助] 各位大哥能帮看下这段程序啥意思

3008202060 2014-6-26 15:26 楼主

module demux(
input clk_108m,
input clk_27m,
input[7:0] vin_data,
output reg[7:0] vout_data_ch0,
output reg[7:0] vout_data_ch1,
output reg[7:0] vout_data_ch2,
output reg[7:0] vout_data_ch3
);
reg[1:0] vin_cnt;
reg[7:0] data0,data1,data2,data3;
reg[7:0] data0_d0;
reg[7:0] data1_d0;
reg[7:0] data2_d0;
reg[7:0] data3_d0;
reg[7:0] data0_d1;
reg[7:0] data0_d2;
reg[7:0] data0_d3;
reg[7:0] data0_d4;
reg[3:0] data0_id;
always@(posedge clk_108m)
begin
vin_cnt <= vin_cnt + 2'd1;
end

always@(posedge clk_108m)
begin
case(vin_cnt)
2'd0:
begin
data0 <= vin_data;
data1 <= data1;
data2 <= data2;
data3 <= data3;
end
2'd1:
begin
data0 <= data0;
data1 <= vin_data;
data2 <= data2;
data3 <= data3;
end
2'd2:
begin
data0 <= data0;
data1 <= data1;
data2 <= vin_data;
data3 <= data3;
end
2'd3:
begin
data0 <= data0;
data1 <= data1;
data2 <= data2;
data3 <= vin_data;
end
default:
begin
data0 <= data0;
data1 <= data1;
data2 <= data2;
data3 <= data3;
end
endcase
end

always@(posedge clk_27m)
begin
data0_d0 <= data0;
data1_d0 <= data1;
data2_d0 <= data2;
data3_d0 <= data3;
data0_d1 <= data0_d0;
data0_d2 <= data0_d1;
data0_d3 <= data0_d2;
data0_d4 <= data0_d3;
end

always@(posedge clk_27m)
begin
if(data0_d4 == 8'hff && data0_d3 == 8'h00 && data0_d2 == 8'h00)
data0_id <= data0_d1[3:0];
else
data0_id <= data0_id;
end
always@(posedge clk_27m)
begin
case(data0_id)
4'd0:
begin
vout_data_ch0 <= data0_d0;
vout_data_ch1 <= data1_d0;
vout_data_ch2 <= data2_d0;
vout_data_ch3 <= data3_d0;
end
4'd1:
begin
vout_data_ch0 <= data3_d0;
vout_data_ch1 <= data0_d0;
vout_data_ch2 <= data1_d0;
vout_data_ch3 <= data2_d0;
end
4'd2:
begin
vout_data_ch0 <= data2_d0;
vout_data_ch1 <= data3_d0;
vout_data_ch2 <= data0_d0;
vout_data_ch3 <= data1_d0;
end
4'd3:
begin
vout_data_ch0 <= data1_d0;
vout_data_ch1 <= data2_d0;
vout_data_ch2 <= data3_d0;
vout_data_ch3 <= data0_d0;
end
default:
begin
vout_data_ch0 <= data0_d0;
vout_data_ch1 <= data1_d0;
vout_data_ch2 <= data2_d0;
vout_data_ch3 <= data3_d0;
end
endcase
end

endmodule