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// Parameter LE tells us if we are little-endian.
// Little-endian means send lower 16 bits first.
// Default is big endian (network order), send upper bits first.
module fifo72_to_fifo36
#(parameter LE=0)
(input clk, input reset, input clear,
input [71:0] f72_datain,
input f72_src_rdy_i,
output f72_dst_rdy_o,
output [35:0] f36_dataout,
output f36_src_rdy_o,
input f36_dst_rdy_i );
wire [35:0] f36_data_int;
wire f36_src_rdy_int, f36_dst_rdy_int;
wire [71:0] f72_data_int;
wire f72_src_rdy_int, f72_dst_rdy_int;
// Shortfifo on input to guarantee no deadlock
fifo_short #(.WIDTH(72)) head_fifo
(.clk(clk),.reset(reset),.clear(clear),
.datain(f72_datain), .src_rdy_i(f72_src_rdy_i), .dst_rdy_o(f72_dst_rdy_o),
.dataout(f72_data_int), .src_rdy_o(f72_src_rdy_int), .dst_rdy_i(f72_dst_rdy_int),
.space(),.occupied() );
// Main fifo72_to_fifo36, needs shortfifos to guarantee no deadlock
wire [2:0] f72_occ_int = f72_data_int[68:66];
wire f72_sof_int = f72_data_int[64];
wire f72_eof_int = f72_data_int[65];
reg phase;
wire half_line = f72_eof_int & ( (f72_occ_int==1)|(f72_occ_int==2)|(f72_occ_int==3)|(f72_occ_int==4) );
assign f36_data_int[31:0] = (LE ^ phase) ? f72_data_int[31:0] : f72_data_int[63:32];
assign f36_data_int[32] = phase ? 0 : f72_sof_int;
assign f36_data_int[33] = phase ? f72_eof_int : half_line;
assign f36_data_int[35:34] = f36_data_int[33] ? f72_occ_int[1:0] : 2'b00;
assign f36_src_rdy_int = f72_src_rdy_int;
assign f72_dst_rdy_int = (phase | half_line) & f36_dst_rdy_int;
wire f36_xfer = f36_src_rdy_int & f36_dst_rdy_int;
wire f72_xfer = f72_src_rdy_int & f72_dst_rdy_int;
always @(posedge clk)
if(reset)
phase <= 0;
else if(f72_xfer)
phase <= 0;
else if(f36_xfer)
phase <= 1;
// Shortfifo on output to guarantee no deadlock
fifo_short #(.WIDTH(36)) tail_fifo
(.clk(clk),.reset(reset),.clear(clear),
.datain(f36_data_int), .src_rdy_i(f36_src_rdy_int), .dst_rdy_o(f36_dst_rdy_int),
.dataout(f36_dataout), .src_rdy_o(f36_src_rdy_o), .dst_rdy_i(f36_dst_rdy_i),
.space(),.occupied() );
endmodule // fifo72_to_fifo36
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