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//
// Copyright 2013 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
// Copyright 2019 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: LGPL-3.0-or-later
//
// Quantize chdr packets to a configurable quantum value. o_tlast and
// i_tready will be held off until the entire quantized packet is xferred.
// If quantum is changed, it is the responsibility of the client to clear
// this module. error is asserted if a packet is larger than the quantum
// error can be reset by asserting reset or clear.
`default_nettype none
module chdr_chunker # (
parameter PAD_VALUE = 64'hFFFFFFFF_FFFFFFFF,
HOLD_ERROR = 1'b1 // If high, hold error until reset, else pulse
) (
input wire clk,
input wire reset,
input wire clear,
input wire [15:0] frame_size,
input wire [63:0] i_tdata,
input wire i_tlast,
input wire i_tvalid,
output reg i_tready,
output wire [63:0] o_tdata,
output wire o_tlast,
output reg o_tvalid,
input wire o_tready,
output wire error
);
localparam ST_HEADER = 2'd0;
localparam ST_DATA = 2'd1;
localparam ST_PADDING = 2'd2;
localparam ST_ERROR = 2'd3;
reg [1:0] state;
reg [15:0] frame_rem;
// axi_len = ceil(length / 8)
wire [15:0] chdr_len_ceil = i_tdata[31:16] + 16'd7;
wire [15:0] axi_len = {3'b000, chdr_len_ceil[15:3]};
always @(posedge clk) begin
if (reset | clear) begin
state <= ST_HEADER;
frame_rem <= 16'd0;
end else if ((state == ST_ERROR) & i_tlast & i_tvalid & !HOLD_ERROR) begin
state <= ST_HEADER;
frame_rem <= 16'd0;
end else if (o_tready) begin
case (state)
ST_HEADER: begin
if (i_tvalid) begin
if ((axi_len > frame_size) | (axi_len == 16'd0))
state <= ST_ERROR;
else if (i_tlast)
state <= ST_PADDING;
else
state <= ST_DATA;
frame_rem <= frame_size - 16'd1;
end
end
ST_DATA: begin
if (i_tvalid) begin
if (i_tlast) begin
state <= o_tlast ? ST_HEADER : ST_PADDING;
frame_rem <= o_tlast ? 16'd0 : (frame_rem - 16'd1);
end else begin
state <= ST_DATA;
frame_rem <= frame_rem - 16'd1;
end
end
end
ST_PADDING: begin
if (o_tlast) begin
state <= ST_HEADER;
frame_rem <= 16'd0;
end else begin
state <= ST_PADDING;
frame_rem <= frame_rem - 16'd1;
end
end
endcase
end
end
always @(*) begin
case (state)
ST_HEADER: begin
i_tready = o_tready;
o_tvalid = (axi_len <= frame_size) & (axi_len > 16'd0) & i_tvalid;
end
ST_DATA: begin
i_tready = o_tready;
o_tvalid = i_tvalid;
end
ST_PADDING: begin
i_tready = 1'b0;
o_tvalid = 1'b1;
end
ST_ERROR: begin
i_tready = 1'b1;
o_tvalid = 1'b0;
end
default: begin
i_tready = 1'b0;
o_tvalid = 1'b0;
end
endcase
end
assign o_tlast = (frame_rem != 16'd0) ? (frame_rem == 16'd1) : (axi_len == 16'd1);
assign o_tdata = (state == ST_PADDING) ? PAD_VALUE : i_tdata;
assign error = (state == ST_ERROR);
endmodule // chdr_chunker
`default_nettype wire
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