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// Copyright 2012 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: LGPL-3.0-or-later
// axi_mux -- takes 4 64-bit AXI stream, merges them to 1 output channel
// Round-robin if PRIO=0, priority if PRIO=1 (lower number ports get priority)
// Bubble cycles are inserted after each packet in PRIO mode, or on wraparound in Round Robin mode
module axi_mux4
#(parameter PRIO=0,
parameter WIDTH=64,
parameter BUFFER=0)
(input clk, input reset, input clear,
input [WIDTH-1:0] i0_tdata, input i0_tlast, input i0_tvalid, output i0_tready,
input [WIDTH-1:0] i1_tdata, input i1_tlast, input i1_tvalid, output i1_tready,
input [WIDTH-1:0] i2_tdata, input i2_tlast, input i2_tvalid, output i2_tready,
input [WIDTH-1:0] i3_tdata, input i3_tlast, input i3_tvalid, output i3_tready,
output [WIDTH-1:0] o_tdata, output o_tlast, output o_tvalid, input o_tready);
wire [WIDTH-1:0] o_tdata_int;
wire o_tlast_int, o_tvalid_int, o_tready_int;
reg [3:0] mx_state;
localparam MX_IDLE = 4'b0000;
localparam MX_0 = 4'b0001;
localparam MX_1 = 4'b0010;
localparam MX_2 = 4'b0100;
localparam MX_3 = 4'b1000;
always @(posedge clk)
if(reset | clear)
mx_state <= MX_IDLE;
else
case (mx_state)
MX_IDLE :
if(i0_tvalid)
mx_state <= MX_0;
else if(i1_tvalid)
mx_state <= MX_1;
else if(i2_tvalid)
mx_state <= MX_2;
else if(i3_tvalid)
mx_state <= MX_3;
MX_0 :
if(o_tready_int & o_tvalid_int & o_tlast_int)
if(PRIO)
mx_state <= MX_IDLE;
else if(i1_tvalid)
mx_state <= MX_1;
else if(i2_tvalid)
mx_state <= MX_2;
else if(i3_tvalid)
mx_state <= MX_3;
else
mx_state <= MX_IDLE;
MX_1 :
if(o_tready_int & o_tvalid_int & o_tlast_int)
if(PRIO)
mx_state <= MX_IDLE;
else if(i2_tvalid)
mx_state <= MX_2;
else if(i3_tvalid)
mx_state <= MX_3;
else
mx_state <= MX_IDLE;
MX_2 :
if(o_tready_int & o_tvalid_int & o_tlast_int)
if(PRIO)
mx_state <= MX_IDLE;
else if(i3_tvalid)
mx_state <= MX_3;
else
mx_state <= MX_IDLE;
MX_3 :
if(o_tready_int & o_tvalid_int & o_tlast_int)
if(PRIO)
mx_state <= MX_IDLE;
else
mx_state <= MX_IDLE;
default :
mx_state <= MX_IDLE;
endcase // case (mx_state)
assign {i3_tready, i2_tready, i1_tready, i0_tready} = mx_state & {4{o_tready_int}};
assign o_tvalid_int = |(mx_state & ({i3_tvalid, i2_tvalid, i1_tvalid, i0_tvalid}));
assign {o_tlast_int, o_tdata_int} = mx_state[3] ? {i3_tlast, i3_tdata} :
mx_state[2] ? {i2_tlast, i2_tdata} :
mx_state[1] ? {i1_tlast, i1_tdata} :
{i0_tlast, i0_tdata};
generate
if(BUFFER == 0)
begin
assign o_tdata = o_tdata_int;
assign o_tlast = o_tlast_int;
assign o_tvalid = o_tvalid_int;
assign o_tready_int = o_tready;
end
else
axi_fifo_flop2 #(.WIDTH(WIDTH+1)) axi_fifo_flop2
(.clk(clk), .reset(reset), .clear(clear),
.i_tdata({o_tlast_int,o_tdata_int}), .i_tvalid(o_tvalid_int), .i_tready(o_tready_int),
.o_tdata({o_tlast,o_tdata}), .o_tvalid(o_tvalid), .o_tready(o_tready),
.space(), .occupied());
endgenerate
endmodule // axi__mux4
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