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//
// Copyright 2011 Ettus Research LLC
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
module ll8_to_fifo36
(input clk, input reset, input clear,
input [7:0] ll_data,
input ll_sof_n,
input ll_eof_n,
input ll_src_rdy_n,
output ll_dst_rdy_n,
output [35:0] f36_data,
output f36_src_rdy_o,
input f36_dst_rdy_i );
wire f36_write = f36_src_rdy_o & f36_dst_rdy_i;
// Why anybody would use active low in an FPGA is beyond me...
wire ll_sof = ~ll_sof_n;
wire ll_eof = ~ll_eof_n;
wire ll_src_rdy = ~ll_src_rdy_n;
wire ll_dst_rdy;
assign ll_dst_rdy_n = ~ll_dst_rdy;
reg f36_sof, f36_eof;
reg [1:0] f36_occ;
reg [2:0] state;
reg [7:0] dat0, dat1, dat2, dat3;
always @(posedge clk)
if(ll_src_rdy & ((state==0)|f36_write))
f36_sof <= ll_sof;
always @(posedge clk)
if(ll_src_rdy & ((state !=4)|f36_write))
f36_eof <= ll_eof;
always @(posedge clk)
if(ll_eof)
f36_occ <= state[1:0] + 1;
else
f36_occ <= 0;
always @(posedge clk)
if(reset)
state <= 0;
else
if(ll_src_rdy)
case(state)
0 :
if(ll_eof)
state <= 4;
else
state <= 1;
1 :
if(ll_eof)
state <= 4;
else
state <= 2;
2 :
if(ll_eof)
state <= 4;
else
state <= 3;
3 : state <= 4;
4 :
if(f36_dst_rdy_i)
if(ll_eof)
state <= 4;
else
state <= 1;
endcase // case(state)
else
if(f36_write)
state <= 0;
always @(posedge clk)
if(ll_src_rdy & (state==3))
dat3 <= ll_data;
always @(posedge clk)
if(ll_src_rdy & (state==2))
dat2 <= ll_data;
always @(posedge clk)
if(ll_src_rdy & (state==1))
dat1 <= ll_data;
always @(posedge clk)
if(ll_src_rdy & ((state==0) | f36_write))
dat0 <= ll_data;
assign ll_dst_rdy = f36_dst_rdy_i | (state != 4);
assign f36_data = {f36_occ,f36_eof,f36_sof,dat0,dat1,dat2,dat3}; // FIXME endianess
assign f36_src_rdy_o = (state == 4);
endmodule // ll8_to_fifo36
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