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module packet_builder #(parameter NUM_CHAN = 2)(
// System
input rxclk,
input reset,
input [31:0] timestamp_clock,
input [3:0] channels,
// ADC side
input [15:0]chan_fifodata,
input [NUM_CHAN:0]chan_empty,
input [9:0]chan_usedw,
output reg [3:0]rd_select,
output reg chan_rdreq,
// FX2 side
output reg WR,
output reg [15:0]fifodata,
input have_space,
input wire [31:0]rssi_0, input wire [31:0]rssi_1, input wire [31:0]rssi_2,
input wire [31:0]rssi_3, output wire [7:0] debugbus,
input [NUM_CHAN:0] underrun);
// States
`define IDLE 3'd0
`define HEADER1 3'd1
`define HEADER2 3'd2
`define TIMESTAMP 3'd3
`define FORWARD 3'd4
`define MAXPAYLOAD 504
`define PAYLOAD_LEN 8:0
`define TAG 12:9
`define MBZ 15:13
`define CHAN 4:0
`define RSSI 10:5
`define BURST 12:11
`define DROPPED 13
`define UNDERRUN 14
`define OVERRUN 15
reg [NUM_CHAN:0] overrun;
reg [2:0] state;
reg [8:0] read_length;
reg [8:0] payload_len;
reg timestamp_complete;
reg [3:0] check_next;
wire [31:0] true_rssi;
wire [4:0] true_channel;
wire ready_to_send;
assign debugbus = {chan_empty[0], rd_select[0], have_space,
(chan_usedw >= 10'd504), (chan_usedw ==0),
ready_to_send, state[1:0]};
assign true_rssi = (rd_select[1]) ? ((rd_select[0]) ? rssi_3:rssi_2) :
((rd_select[0]) ? rssi_1:rssi_0);
assign true_channel = (check_next == 4'd0 ? 5'h1f : {1'd0, check_next - 4'd1});
assign ready_to_send = (chan_usedw >= 10'd504) || (chan_usedw == 0) ||
((rd_select == NUM_CHAN)&&(chan_usedw > 0));
always @(posedge rxclk)
begin
if (reset)
begin
overrun <= 0;
WR <= 0;
rd_select <= 0;
chan_rdreq <= 0;
timestamp_complete <= 0;
check_next <= 0;
state <= `IDLE;
end
else case (state)
`IDLE: begin
chan_rdreq <= #1 0;
//check if the channel is full
if(~chan_empty[check_next])
begin
if (have_space)
begin
//transmit if the usb buffer have space
//check if we should send
if (ready_to_send)
state <= #1 `HEADER1;
overrun[check_next] <= 0;
end
else
begin
state <= #1 `IDLE;
overrun[check_next] <= 1;
end
rd_select <= #1 check_next;
end
check_next <= #1 (check_next == channels ? 4'd0 : check_next + 4'd1);
end
`HEADER1: begin
fifodata[`PAYLOAD_LEN] <= #1 9'd504;
payload_len <= #1 9'd504;
fifodata[`TAG] <= #1 0;
fifodata[`MBZ] <= #1 0;
WR <= #1 1;
state <= #1 `HEADER2;
read_length <= #1 0;
end
`HEADER2: begin
fifodata[`CHAN] <= #1 true_channel;
fifodata[`RSSI] <= #1 true_rssi[5:0];
fifodata[`BURST] <= #1 0;
fifodata[`DROPPED] <= #1 0;
fifodata[`UNDERRUN] <= #1 (check_next == 0) ? 1'b0 : underrun[true_channel];
fifodata[`OVERRUN] <= #1 (check_next == 0) ? 1'b0 : overrun[true_channel];
state <= #1 `TIMESTAMP;
end
`TIMESTAMP: begin
fifodata <= #1 (timestamp_complete ? timestamp_clock[31:16] : timestamp_clock[15:0]);
timestamp_complete <= #1 ~timestamp_complete;
if (~timestamp_complete)
chan_rdreq <= #1 1;
state <= #1 (timestamp_complete ? `FORWARD : `TIMESTAMP);
end
`FORWARD: begin
read_length <= #1 read_length + 9'd2;
fifodata <= #1 (read_length >= payload_len ? 16'hDEAD : chan_fifodata);
if (read_length >= `MAXPAYLOAD)
begin
WR <= #1 0;
state <= #1 `IDLE;
chan_rdreq <= #1 0;
end
else if (read_length == payload_len - 4)
chan_rdreq <= #1 0;
end
default: begin
//handling error state
state <= `IDLE;
end
endcase
end
endmodule
|
