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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_fifo19
(input clk, input reset, input clear,
input [7:0] ll_data,
input ll_sof,
input ll_eof,
input ll_src_rdy,
output ll_dst_rdy,
output [18:0] f19_data,
output f19_src_rdy_o,
input f19_dst_rdy_i );
// Short FIFO on input to guarantee no deadlock
wire [7:0] ll_data_int;
wire ll_sof_int, ll_eof_int, ll_src_rdy_int, ll_dst_rdy_int;
ll8_shortfifo head_fifo
(.clk(clk), .reset(reset), .clear(clear),
.datain(ll_data), .sof_i(ll_sof), .eof_i(ll_eof),
.error_i(0), .src_rdy_i(ll_src_rdy), .dst_rdy_o(ll_dst_rdy),
.dataout(ll_data_int), .sof_o(ll_sof_int), .eof_o(ll_eof_int),
.error_o(), .src_rdy_o(ll_src_rdy_int), .dst_rdy_i(ll_dst_rdy_int));
// Actual ll8_to_fifo19 which could deadlock if not connected to a shortfifo
localparam XFER_EMPTY = 0;
localparam XFER_HALF = 1;
localparam XFER_HALF_WRITE = 3;
wire [18:0] f19_data_int;
wire f19_sof_int, f19_eof_int, f19_occ_int, f19_src_rdy_int, f19_dst_rdy_int;
wire xfer_out = f19_src_rdy_int & f19_dst_rdy_int;
wire xfer_in = ll_src_rdy_int & ll_dst_rdy_int;
reg hold_sof;
reg [1:0] state;
reg [7:0] hold_reg;
always @(posedge clk)
if(ll_src_rdy_int & (state==XFER_EMPTY))
hold_reg <= ll_data_int;
always @(posedge clk)
if(ll_sof_int & (state==XFER_EMPTY))
hold_sof <= 1;
else if(xfer_out)
hold_sof <= 0;
always @(posedge clk)
if(reset | clear)
state <= XFER_EMPTY;
else
case(state)
XFER_EMPTY :
if(ll_src_rdy_int)
if(ll_eof_int)
state <= XFER_HALF_WRITE;
else
state <= XFER_HALF;
XFER_HALF :
if(ll_src_rdy_int & f19_dst_rdy_int)
state <= XFER_EMPTY;
XFER_HALF_WRITE :
if(f19_dst_rdy_int)
state <= XFER_EMPTY;
endcase // case (state)
assign ll_dst_rdy_int = (state==XFER_EMPTY) | ((state==XFER_HALF)&f19_dst_rdy_int);
assign f19_src_rdy_int= (state==XFER_HALF_WRITE) | ((state==XFER_HALF)&ll_src_rdy_int);
assign f19_sof_int = hold_sof | (ll_sof_int & (state==XFER_HALF));
assign f19_eof_int = (state == XFER_HALF_WRITE) | ll_eof_int;
assign f19_occ_int = (state == XFER_HALF_WRITE);
assign f19_data_int = {f19_occ_int,f19_eof_int,f19_sof_int,hold_reg,ll_data_int};
// Shortfifo on output to guarantee no deadlock
fifo_short #(.WIDTH(19)) tail_fifo
(.clk(clk),.reset(reset),.clear(clear),
.datain(f19_data_int), .src_rdy_i(f19_src_rdy_int), .dst_rdy_o(f19_dst_rdy_int),
.dataout(f19_data), .src_rdy_o(f19_src_rdy_o), .dst_rdy_i(f19_dst_rdy_i),
.space(),.occupied() );
endmodule // ll8_to_fifo19
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