8b/10 encode verilog
时间: 2023-07-01 10:05:26 浏览: 51
8b/10b encoding is a line coding scheme that maps 8-bit data to 10-bit codewords to provide DC balance and ensure sufficient transitions for reliable clock recovery. Here is an example Verilog code for encoding 8b/10b:
```
module encode_8b10b (
input clk,
input [7:0] data_in,
output reg [9:0] data_out,
output reg k
);
reg [4:0] running_disparity;
reg [4:0] next_running_disparity;
reg [3:0] symbol;
always @(posedge clk) begin
// Determine the running disparity
if (data_in[7] == 1'b1) begin
next_running_disparity = running_disparity + 1;
end else begin
next_running_disparity = running_disparity - 1;
end
// Encode the data
case (data_in)
8'hFC: symbol = 4'hC;
8'hFD: symbol = 4'h5;
8'hFE: symbol = 4'h6;
8'hFF: symbol = 4'h9;
default: symbol = {data_in[7], data_in[6], data_in[5], data_in[4], data_in[3], data_in[2], data_in[1], data_in[0]};
endcase
// Determine the k character
if (next_running_disparity > 4 || next_running_disparity < -4) begin
k = ~k;
if (next_running_disparity > 0) begin
symbol = {symbol[3:0], ~symbol[4]};
end else begin
symbol = {symbol[3:0], symbol[4]};
end
end else begin
k = k;
symbol = {symbol[3:0], running_disparity};
end
// Update the running disparity
running_disparity <= next_running_disparity;
// Output the encoded data
data_out = {symbol, k};
end
endmodule
```
This code takes in an 8-bit data input `data_in` and a clock input `clk`, and outputs the 10-bit encoded data `data_out` and the k character `k`. The running disparity is calculated and updated using a simple algorithm based on the number of ones in the input data. The data is then encoded using a lookup table, and the k character is added based on the running disparity.