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//
// Copyright 2014 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: LGPL-3.0-or-later
//
module periodic_framer #(
parameter SR_FRAME_LEN = 0,
parameter SR_GAP_LEN = 1,
parameter SR_OFFSET = 2,
parameter SR_NUMBER_SYMBOLS_MAX = 3,
parameter SR_NUMBER_SYMBOLS_SHORT = 4,
// Skip a set number of gaps at the beginning. Use 1 to properly frame 802.11 long preamble.
parameter SKIP_GAPS = 1,
parameter WIDTH = 32)
(
input clk, input reset, input clear,
input set_stb, input [7:0] set_addr, input [31:0] set_data,
input [WIDTH-1:0] stream_i_tdata, input stream_i_tlast, input stream_i_tvalid, output stream_i_tready,
output [WIDTH-1:0] stream_o_tdata, output stream_o_tlast, output stream_o_tvalid, input stream_o_tready,
output reg sof, output reg eof);
wire [15:0] frame_len;
wire [15:0] gap_len;
wire [15:0] offset;
wire [15:0] numsymbols_max, numsymbols_thisburst, numsymbols_short;
wire [15:0] burst_len;
wire set_numsymbols;
wire consume;
reg [15:0] counter;
reg [$clog2(SKIP_GAPS):0] skip_cnt;
reg [15:0] numsymbols;
setting_reg #(.my_addr(SR_FRAME_LEN), .width(16)) reg_frame_len (
.clk(clk), .rst(reset), .strobe(set_stb), .addr(set_addr), .in(set_data),
.out(frame_len), .changed());
setting_reg #(.my_addr(SR_GAP_LEN), .width(16)) reg_gap_len (
.clk(clk), .rst(reset), .strobe(set_stb), .addr(set_addr), .in(set_data),
.out(gap_len), .changed());
setting_reg #(.my_addr(SR_OFFSET), .width(16)) reg_offset (
.clk(clk), .rst(reset), .strobe(set_stb), .addr(set_addr), .in(set_data),
.out(offset), .changed());
setting_reg #(.my_addr(SR_NUMBER_SYMBOLS_MAX), .width(16)) reg_max_symbols (
.clk(clk), .rst(reset), .strobe(set_stb), .addr(set_addr), .in(set_data),
.out(numsymbols_max), .changed());
setting_reg #(.my_addr(SR_NUMBER_SYMBOLS_SHORT), .width(16)) reg_symbols_short (
.clk(clk), .rst(reset), .strobe(set_stb), .addr(set_addr), .in(set_data),
.out(numsymbols_short), .changed(set_numsymbols));
reg [1:0] state;
localparam ST_WAIT_FOR_TRIG = 2'd0;
localparam ST_DO_OFFSET = 2'd1;
localparam ST_FRAME = 2'd2;
localparam ST_GAP = 2'd3;
reg shorten_burst;
always @(posedge clk) begin
if (reset | clear) begin
shorten_burst <= 1'b0;
end else if (set_numsymbols) begin
shorten_burst <= 1'b1;
end else if(state == ST_WAIT_FOR_TRIG) begin
shorten_burst <= 1'b0;
end
end
assign numsymbols_thisburst = shorten_burst ? numsymbols_short : numsymbols_max;
always @(posedge clk) begin
if (reset | clear) begin
eof <= 1'b0;
sof <= 1'b0;
counter <= 1;
skip_cnt <= 0;
numsymbols <= 16'd1;
state <= ST_WAIT_FOR_TRIG;
end else begin
if (consume) begin
case(state)
ST_WAIT_FOR_TRIG : begin
eof <= 1'b0;
skip_cnt <= 0;
if (stream_i_tlast) begin
counter <= 16'b1;
if (offset == 0) begin
state <= ST_FRAME;
end else begin
state <= ST_DO_OFFSET;
end
end
end
ST_DO_OFFSET : begin
if (counter >= offset) begin
sof <= 1'b1;
counter <= 16'b1;
numsymbols <= 16'd1;
state <= ST_FRAME;
end else begin
counter <= counter + 16'd1;
end
end
ST_FRAME : begin
if (counter >= frame_len) begin
sof <= 1'b0;
counter <= 1;
numsymbols <= numsymbols + 1;
if (numsymbols >= numsymbols_thisburst) begin
eof <= 1'b1;
state <= ST_WAIT_FOR_TRIG;
end else begin
if (skip_cnt < SKIP_GAPS) begin
skip_cnt <= skip_cnt + 1;
state <= ST_FRAME;
end else begin
state <= ST_GAP;
end
end
end else begin
counter <= counter + 16'd1;
end
end
ST_GAP : begin
if (counter >= gap_len) begin
state <= ST_FRAME;
counter <= 1;
end else begin
counter <= counter + 16'd1;
end
end
endcase
end
end
end
assign stream_o_tdata = stream_i_tdata;
assign stream_o_tlast = (state == ST_FRAME) & (counter >= frame_len);
assign stream_o_tvalid = stream_i_tvalid & (state == ST_FRAME);
assign stream_i_tready = consume;
assign consume = stream_i_tvalid & ((state != ST_FRAME) | stream_o_tready);
endmodule // periodic_framer
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