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corundum/rtl/axis_arb_mux_4.v
Alex Forencich 8e5ec36ced Optimize axis_arb_mux and improve latency
2018-08-09 18:40:50 -07:00

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Verilog
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/*
Copyright (c) 2014-2018 Alex Forencich
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
// Language: Verilog 2001
`timescale 1ns / 1ps
/*
* AXI4-Stream 4 port arbitrated multiplexer
*/
module axis_arb_mux_4 #
(
parameter DATA_WIDTH = 8,
parameter KEEP_ENABLE = (DATA_WIDTH>8),
parameter KEEP_WIDTH = (DATA_WIDTH/8),
parameter ID_ENABLE = 0,
parameter ID_WIDTH = 8,
parameter DEST_ENABLE = 0,
parameter DEST_WIDTH = 8,
parameter USER_ENABLE = 1,
parameter USER_WIDTH = 1,
// arbitration type: "PRIORITY" or "ROUND_ROBIN"
parameter ARB_TYPE = "PRIORITY",
// LSB priority: "LOW", "HIGH"
parameter LSB_PRIORITY = "HIGH"
)
(
input wire clk,
input wire rst,
/*
* AXI inputs
*/
input wire [DATA_WIDTH-1:0] input_0_axis_tdata,
input wire [KEEP_WIDTH-1:0] input_0_axis_tkeep,
input wire input_0_axis_tvalid,
output wire input_0_axis_tready,
input wire input_0_axis_tlast,
input wire [ID_WIDTH-1:0] input_0_axis_tid,
input wire [DEST_WIDTH-1:0] input_0_axis_tdest,
input wire [USER_WIDTH-1:0] input_0_axis_tuser,
input wire [DATA_WIDTH-1:0] input_1_axis_tdata,
input wire [KEEP_WIDTH-1:0] input_1_axis_tkeep,
input wire input_1_axis_tvalid,
output wire input_1_axis_tready,
input wire input_1_axis_tlast,
input wire [ID_WIDTH-1:0] input_1_axis_tid,
input wire [DEST_WIDTH-1:0] input_1_axis_tdest,
input wire [USER_WIDTH-1:0] input_1_axis_tuser,
input wire [DATA_WIDTH-1:0] input_2_axis_tdata,
input wire [KEEP_WIDTH-1:0] input_2_axis_tkeep,
input wire input_2_axis_tvalid,
output wire input_2_axis_tready,
input wire input_2_axis_tlast,
input wire [ID_WIDTH-1:0] input_2_axis_tid,
input wire [DEST_WIDTH-1:0] input_2_axis_tdest,
input wire [USER_WIDTH-1:0] input_2_axis_tuser,
input wire [DATA_WIDTH-1:0] input_3_axis_tdata,
input wire [KEEP_WIDTH-1:0] input_3_axis_tkeep,
input wire input_3_axis_tvalid,
output wire input_3_axis_tready,
input wire input_3_axis_tlast,
input wire [ID_WIDTH-1:0] input_3_axis_tid,
input wire [DEST_WIDTH-1:0] input_3_axis_tdest,
input wire [USER_WIDTH-1:0] input_3_axis_tuser,
/*
* AXI output
*/
output wire [DATA_WIDTH-1:0] output_axis_tdata,
output wire [KEEP_WIDTH-1:0] output_axis_tkeep,
output wire output_axis_tvalid,
input wire output_axis_tready,
output wire output_axis_tlast,
output wire [ID_WIDTH-1:0] output_axis_tid,
output wire [DEST_WIDTH-1:0] output_axis_tdest,
output wire [USER_WIDTH-1:0] output_axis_tuser
);
wire [3:0] request;
wire [3:0] acknowledge;
wire [3:0] grant;
wire grant_valid;
wire [1:0] grant_encoded;
// internal datapath
reg [DATA_WIDTH-1:0] output_axis_tdata_int;
reg [KEEP_WIDTH-1:0] output_axis_tkeep_int;
reg output_axis_tvalid_int;
reg output_axis_tready_int_reg = 1'b0;
reg output_axis_tlast_int;
reg [ID_WIDTH-1:0] output_axis_tid_int;
reg [DEST_WIDTH-1:0] output_axis_tdest_int;
reg [USER_WIDTH-1:0] output_axis_tuser_int;
wire output_axis_tready_int_early;
assign input_0_axis_tready = grant[0] & output_axis_tready_int_reg;
assign input_1_axis_tready = grant[1] & output_axis_tready_int_reg;
assign input_2_axis_tready = grant[2] & output_axis_tready_int_reg;
assign input_3_axis_tready = grant[3] & output_axis_tready_int_reg;
// mux for incoming packet
reg [DATA_WIDTH-1:0] current_input_tdata;
reg [KEEP_WIDTH-1:0] current_input_tkeep;
reg current_input_tvalid;
reg current_input_tready;
reg current_input_tlast;
reg [ID_WIDTH-1:0] current_input_tid;
reg [DEST_WIDTH-1:0] current_input_tdest;
reg [USER_WIDTH-1:0] current_input_tuser;
always @* begin
case (grant_encoded)
2'd0: begin
current_input_tdata = input_0_axis_tdata;
current_input_tkeep = input_0_axis_tkeep;
current_input_tvalid = input_0_axis_tvalid;
current_input_tready = input_0_axis_tready;
current_input_tlast = input_0_axis_tlast;
current_input_tid = input_0_axis_tid;
current_input_tdest = input_0_axis_tdest;
current_input_tuser = input_0_axis_tuser;
end
2'd1: begin
current_input_tdata = input_1_axis_tdata;
current_input_tkeep = input_1_axis_tkeep;
current_input_tvalid = input_1_axis_tvalid;
current_input_tready = input_1_axis_tready;
current_input_tlast = input_1_axis_tlast;
current_input_tid = input_1_axis_tid;
current_input_tdest = input_1_axis_tdest;
current_input_tuser = input_1_axis_tuser;
end
2'd2: begin
current_input_tdata = input_2_axis_tdata;
current_input_tkeep = input_2_axis_tkeep;
current_input_tvalid = input_2_axis_tvalid;
current_input_tready = input_2_axis_tready;
current_input_tlast = input_2_axis_tlast;
current_input_tid = input_2_axis_tid;
current_input_tdest = input_2_axis_tdest;
current_input_tuser = input_2_axis_tuser;
end
2'd3: begin
current_input_tdata = input_3_axis_tdata;
current_input_tkeep = input_3_axis_tkeep;
current_input_tvalid = input_3_axis_tvalid;
current_input_tready = input_3_axis_tready;
current_input_tlast = input_3_axis_tlast;
current_input_tid = input_3_axis_tid;
current_input_tdest = input_3_axis_tdest;
current_input_tuser = input_3_axis_tuser;
end
default: begin
current_input_tdata = {DATA_WIDTH{1'b0}};
current_input_tkeep = {KEEP_WIDTH{1'b0}};
current_input_tvalid = 1'b0;
current_input_tready = 1'b0;
current_input_tlast = 1'b0;
current_input_tid = {ID_WIDTH{1'b0}};
current_input_tdest = {DEST_WIDTH{1'b0}};
current_input_tuser = {USER_WIDTH{1'b0}};
end
endcase
end
// arbiter instance
arbiter #(
.PORTS(4),
.TYPE(ARB_TYPE),
.BLOCK("ACKNOWLEDGE"),
.LSB_PRIORITY(LSB_PRIORITY)
)
arb_inst (
.clk(clk),
.rst(rst),
.request(request),
.acknowledge(acknowledge),
.grant(grant),
.grant_valid(grant_valid),
.grant_encoded(grant_encoded)
);
// request generation
assign request[0] = input_0_axis_tvalid & ~acknowledge[0];
assign request[1] = input_1_axis_tvalid & ~acknowledge[1];
assign request[2] = input_2_axis_tvalid & ~acknowledge[2];
assign request[3] = input_3_axis_tvalid & ~acknowledge[3];
// acknowledge generation
assign acknowledge[0] = grant[0] & input_0_axis_tvalid & input_0_axis_tready & input_0_axis_tlast;
assign acknowledge[1] = grant[1] & input_1_axis_tvalid & input_1_axis_tready & input_1_axis_tlast;
assign acknowledge[2] = grant[2] & input_2_axis_tvalid & input_2_axis_tready & input_2_axis_tlast;
assign acknowledge[3] = grant[3] & input_3_axis_tvalid & input_3_axis_tready & input_3_axis_tlast;
always @* begin
// pass through selected packet data
output_axis_tdata_int = current_input_tdata;
output_axis_tkeep_int = current_input_tkeep;
output_axis_tvalid_int = current_input_tvalid & current_input_tready;
output_axis_tlast_int = current_input_tlast;
output_axis_tid_int = current_input_tid;
output_axis_tdest_int = current_input_tdest;
output_axis_tuser_int = current_input_tuser;
end
// output datapath logic
reg [DATA_WIDTH-1:0] output_axis_tdata_reg = {DATA_WIDTH{1'b0}};
reg [KEEP_WIDTH-1:0] output_axis_tkeep_reg = {KEEP_WIDTH{1'b0}};
reg output_axis_tvalid_reg = 1'b0, output_axis_tvalid_next;
reg output_axis_tlast_reg = 1'b0;
reg [ID_WIDTH-1:0] output_axis_tid_reg = {ID_WIDTH{1'b0}};
reg [DEST_WIDTH-1:0] output_axis_tdest_reg = {DEST_WIDTH{1'b0}};
reg [USER_WIDTH-1:0] output_axis_tuser_reg = {USER_WIDTH{1'b0}};
reg [DATA_WIDTH-1:0] temp_axis_tdata_reg = {DATA_WIDTH{1'b0}};
reg [KEEP_WIDTH-1:0] temp_axis_tkeep_reg = {KEEP_WIDTH{1'b0}};
reg temp_axis_tvalid_reg = 1'b0, temp_axis_tvalid_next;
reg temp_axis_tlast_reg = 1'b0;
reg [ID_WIDTH-1:0] temp_axis_tid_reg = {ID_WIDTH{1'b0}};
reg [DEST_WIDTH-1:0] temp_axis_tdest_reg = {DEST_WIDTH{1'b0}};
reg [USER_WIDTH-1:0] temp_axis_tuser_reg = {USER_WIDTH{1'b0}};
// datapath control
reg store_axis_int_to_output;
reg store_axis_int_to_temp;
reg store_axis_temp_to_output;
assign output_axis_tdata = output_axis_tdata_reg;
assign output_axis_tkeep = KEEP_ENABLE ? output_axis_tkeep_reg : {KEEP_WIDTH{1'b1}};
assign output_axis_tvalid = output_axis_tvalid_reg;
assign output_axis_tlast = output_axis_tlast_reg;
assign output_axis_tid = ID_ENABLE ? output_axis_tid_reg : {ID_WIDTH{1'b0}};
assign output_axis_tdest = DEST_ENABLE ? output_axis_tdest_reg : {DEST_WIDTH{1'b0}};
assign output_axis_tuser = USER_ENABLE ? output_axis_tuser_reg : {USER_WIDTH{1'b0}};
// enable ready input next cycle if output is ready or the temp reg will not be filled on the next cycle (output reg empty or no input)
assign output_axis_tready_int_early = output_axis_tready | (~temp_axis_tvalid_reg & (~output_axis_tvalid_reg | ~output_axis_tvalid_int));
always @* begin
// transfer sink ready state to source
output_axis_tvalid_next = output_axis_tvalid_reg;
temp_axis_tvalid_next = temp_axis_tvalid_reg;
store_axis_int_to_output = 1'b0;
store_axis_int_to_temp = 1'b0;
store_axis_temp_to_output = 1'b0;
if (output_axis_tready_int_reg) begin
// input is ready
if (output_axis_tready | ~output_axis_tvalid_reg) begin
// output is ready or currently not valid, transfer data to output
output_axis_tvalid_next = output_axis_tvalid_int;
store_axis_int_to_output = 1'b1;
end else begin
// output is not ready, store input in temp
temp_axis_tvalid_next = output_axis_tvalid_int;
store_axis_int_to_temp = 1'b1;
end
end else if (output_axis_tready) begin
// input is not ready, but output is ready
output_axis_tvalid_next = temp_axis_tvalid_reg;
temp_axis_tvalid_next = 1'b0;
store_axis_temp_to_output = 1'b1;
end
end
always @(posedge clk) begin
if (rst) begin
output_axis_tvalid_reg <= 1'b0;
output_axis_tready_int_reg <= 1'b0;
temp_axis_tvalid_reg <= 1'b0;
end else begin
output_axis_tvalid_reg <= output_axis_tvalid_next;
output_axis_tready_int_reg <= output_axis_tready_int_early;
temp_axis_tvalid_reg <= temp_axis_tvalid_next;
end
// datapath
if (store_axis_int_to_output) begin
output_axis_tdata_reg <= output_axis_tdata_int;
output_axis_tkeep_reg <= output_axis_tkeep_int;
output_axis_tlast_reg <= output_axis_tlast_int;
output_axis_tid_reg <= output_axis_tid_int;
output_axis_tdest_reg <= output_axis_tdest_int;
output_axis_tuser_reg <= output_axis_tuser_int;
end else if (store_axis_temp_to_output) begin
output_axis_tdata_reg <= temp_axis_tdata_reg;
output_axis_tkeep_reg <= temp_axis_tkeep_reg;
output_axis_tlast_reg <= temp_axis_tlast_reg;
output_axis_tid_reg <= temp_axis_tid_reg;
output_axis_tdest_reg <= temp_axis_tdest_reg;
output_axis_tuser_reg <= temp_axis_tuser_reg;
end
if (store_axis_int_to_temp) begin
temp_axis_tdata_reg <= output_axis_tdata_int;
temp_axis_tkeep_reg <= output_axis_tkeep_int;
temp_axis_tlast_reg <= output_axis_tlast_int;
temp_axis_tid_reg <= output_axis_tid_int;
temp_axis_tdest_reg <= output_axis_tdest_int;
temp_axis_tuser_reg <= output_axis_tuser_int;
end
end
endmodule
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