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// This has 3 functions:
// Correct the VITA packet length
// [optional] Frame DSP packets with an header line to be handled by the protocol machine
// Hold on to the packet until there is a complete one before allowing to leave
module dsp_framer36
#(parameter BUF_SIZE = 9,
parameter PORT_SEL = 0,
parameter PROT_ENG_FLAGS = 1)
(input clk, input reset, input clear,
input [35:0] data_i, input src_rdy_i, output dst_rdy_o,
output [35:0] data_o, output src_rdy_o, input dst_rdy_i);
wire dfifo_in_dst_rdy, dfifo_in_src_rdy, dfifo_out_dst_rdy, dfifo_out_src_rdy;
wire tfifo_in_dst_rdy, tfifo_in_src_rdy, tfifo_out_dst_rdy, tfifo_out_src_rdy;
wire do_xfer_in = dfifo_in_src_rdy & dfifo_in_dst_rdy;
wire do_xfer_out = src_rdy_o & dst_rdy_i;
wire have_space = dfifo_in_dst_rdy & tfifo_in_dst_rdy;
reg [15:0] pkt_len_in, pkt_len_out;
wire [15:0] tfifo_data;
wire [35:0] dfifo_out_data;
assign dst_rdy_o = have_space;
assign dfifo_in_src_rdy = src_rdy_i & have_space;
fifo_cascade #(.WIDTH(36), .SIZE(BUF_SIZE)) dfifo
(.clk(clk), .reset(reset), .clear(clear),
.datain(data_i), .src_rdy_i(dfifo_in_src_rdy), .dst_rdy_o(dfifo_in_dst_rdy),
.dataout(dfifo_out_data), .src_rdy_o(dfifo_out_src_rdy), .dst_rdy_i(dfifo_out_dst_rdy) );
fifo_short #(.WIDTH(16)) tfifo
(.clk(clk), .reset(reset), .clear(clear),
.datain(pkt_len_in), .src_rdy_i(tfifo_in_src_rdy), .dst_rdy_o(tfifo_in_dst_rdy),
.dataout(tfifo_data), .src_rdy_o(tfifo_out_src_rdy), .dst_rdy_i(tfifo_out_dst_rdy),
.space(), .occupied() );
// FIXME won't handle single-line packets, will show wrong length
always @(posedge clk)
if(reset | clear)
pkt_len_in <= 0;
else if(do_xfer_in)
if(data_i[32]) // sof
pkt_len_in <= 2; // fixes off by one since number is stored before increment
else
pkt_len_in <= pkt_len_in + 1;
assign tfifo_in_src_rdy = do_xfer_in & data_i[33]; // store length when at eof in
assign tfifo_out_dst_rdy = do_xfer_out & data_o[33]; // remove length from list at eof out
always @(posedge clk)
if(reset | clear)
pkt_len_out <= (PROT_ENG_FLAGS ? 1'b0 : 1'b1);
else if(do_xfer_out)
if(dfifo_out_data[33]) // eof
pkt_len_out <= (PROT_ENG_FLAGS ? 1'b0 : 1'b1);
else
pkt_len_out <= pkt_len_out + 1;
assign dfifo_out_dst_rdy = do_xfer_out & (pkt_len_out != 0);
wire [1:0] port_sel_bits = PORT_SEL;
assign data_o = (pkt_len_out == 0) ? {3'b000, 1'b1, 13'b0, port_sel_bits, 1'b1, tfifo_data[13:0],2'b00} :
(pkt_len_out == 1) ? {3'b000, (PROT_ENG_FLAGS ? 1'b0: 1'b1), dfifo_out_data[31:16],tfifo_data} :
{dfifo_out_data[35:33], 1'b0, dfifo_out_data[31:0] };
assign src_rdy_o = dfifo_out_src_rdy & tfifo_out_src_rdy;
endmodule // dsp_framer36
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