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//
// Copyright (c) 2026, Apollo Telephone Laboratories.
// Provided under the BSD-3 clause.
//
`include "bus/ari.svh"
//
// Represents an ARI segment frame multiplexer
//
// @clk_i: Clock input
// @reset_i: Reset input
// @ingress_i: Ingress frame input
// @tap_i: Tap port input
// @egress_o: Egress frame output
//
module ari_framemux (
input wire clk_i,
input wire reset_i,
input AriFrame ingress_i,
input AriFrame tap_i,
output AriFrame egress_o
);
// Multiplexer attributes
parameter MUX_PERIOD = 2;
parameter MUX_N_INPUT = 2;
parameter MUX_N_STATES = (MUX_PERIOD * MUX_N_INPUT);
// Multiplexer states
parameter MUX_STATE_INGRESS0 = 0;
parameter MUX_STATE_INGRESS1 = 1;
parameter MUX_STATE_TAP0 = 2;
parameter MUX_STATE_TAP1 = 3;
// TDM selector
logic [2:0] mux_sel;
//
// Handle reset logic and time division multiplexing for
// frame routing. If there is nothing on the channel that
// is currently being selected, we are to route the other
// channel instead.
//
always_ff @(posedge clk_i) begin
if (reset_i) begin
mux_sel <= 0;
egress_o <= 0;
end else begin
case (mux_sel)
// TDM ingress slice
MUX_STATE_INGRESS0: begin
if (ingress_i == 0) begin
egress_o <= tap_i;
end else begin
egress_o <= ingress_i;
end
end
MUX_STATE_INGRESS1: begin
if (ingress_i == 0) begin
egress_o <= tap_i;
end else begin
egress_o <= ingress_i;
end
end
// TDM tap slice
MUX_STATE_TAP0: begin
if (tap_i == 0) begin
egress_o <= ingress_i;
end else begin
egress_o <= tap_i;
end
end
MUX_STATE_TAP1: begin
if (tap_i == 0) begin
egress_o <= ingress_i;
end else begin
egress_o <= tap_i;
end
end
endcase
end
if (!reset_i && mux_sel < MUX_N_STATES) begin
mux_sel <= mux_sel + 1;
end else if (!reset_i && mux_sel >= MUX_N_STATES) begin
mux_sel <= 0;
end
end
endmodule
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