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module fifo_watcher
(input clk, input reset, input clear,
input src_rdy1, input dst_rdy1, input sof1, input eof1,
input src_rdy2, input dst_rdy2, input sof2, input eof2,
output reg have_packet, output [15:0] length, output reg bus_error);
wire write = src_rdy1 & dst_rdy1 & eof1;
wire read = src_rdy2 & dst_rdy2 & eof2;
wire have_packet_int;
reg [15:0] counter;
fifo_short #(.WIDTH(16)) frame_lengths
(.clk(clk), .reset(reset), .clear(clear),
.datain(counter), .src_rdy_i(write), .dst_rdy_o(),
.dataout(length), .src_rdy_o(have_packet_int), .dst_rdy_i(read) );
always @(posedge clk)
if(reset | clear)
counter <= 1; // Start at 1
else if(src_rdy1 & dst_rdy1)
if(eof1)
counter <= 1;
else
counter <= counter + 1;
always @(posedge clk)
if(reset | clear)
bus_error <= 0;
else if(dst_rdy2 & ~src_rdy2)
bus_error <= 1;
else if(read & ~have_packet_int)
bus_error <= 1;
reg in_packet;
always @(posedge clk)
if(reset | clear)
have_packet <= 0;
else
have_packet <= have_packet_int & ~in_packet;
always @(posedge clk)
if(reset | clear)
in_packet <= 0;
else if(src_rdy2 & dst_rdy2)
if(eof2)
in_packet <= 0;
else
in_packet <= 1;
endmodule // fifo_watcher
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