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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 fifo19_to_fifo36
#(parameter LE=0)
(input clk, input reset, input clear,
input [18:0] f19_datain,
input f19_src_rdy_i,
output f19_dst_rdy_o,
output [35:0] f36_dataout,
output f36_src_rdy_o,
input f36_dst_rdy_i,
output [31:0] debug
);
reg f36_sof, f36_eof;
reg [1:0] f36_occ;
reg [1:0] state;
reg [15:0] dat0, dat1;
wire f19_sof = f19_datain[16];
wire f19_eof = f19_datain[17];
wire f19_occ = f19_datain[18];
wire xfer_out = f36_src_rdy_o & f36_dst_rdy_i;
always @(posedge clk)
if(f19_src_rdy_i & ((state==0)|xfer_out))
f36_sof <= f19_sof;
always @(posedge clk)
if(f19_src_rdy_i & ((state != 2)|xfer_out))
f36_eof <= f19_eof;
always @(posedge clk)
if(reset)
begin
state <= 0;
f36_occ <= 0;
end
else
if(f19_src_rdy_i)
case(state)
0 :
begin
dat0 <= f19_datain;
if(f19_eof)
begin
state <= 2;
f36_occ <= f19_occ ? 2'b01 : 2'b10;
end
else
state <= 1;
end
1 :
begin
dat1 <= f19_datain;
state <= 2;
if(f19_eof)
f36_occ <= f19_occ ? 2'b11 : 2'b00;
end
2 :
if(xfer_out)
begin
dat0 <= f19_datain;
if(f19_eof) // remain in state 2 if we are at eof
f36_occ <= f19_occ ? 2'b01 : 2'b10;
else
state <= 1;
end
endcase // case(state)
else
if(xfer_out)
begin
state <= 0;
f36_occ <= 0;
end
assign f19_dst_rdy_o = xfer_out | (state != 2);
assign f36_dataout = LE ? {f36_occ,f36_eof,f36_sof,dat1,dat0} :
{f36_occ,f36_eof,f36_sof,dat0,dat1};
assign f36_src_rdy_o = (state == 2);
assign debug = state;
endmodule // fifo19_to_fifo36
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