module axi_crossbar_rd #
(
    // Number of AXI inputs (slave interfaces)
    parameter S_COUNT = 4,
    // Number of AXI outputs (master interfaces)
    parameter M_COUNT = 4,
    // Width of data bus in bits
    parameter DATA_WIDTH = 32,
    // Width of address bus in bits
    parameter ADDR_WIDTH = 32,
    // Width of wstrb (width of data bus in words)
    parameter STRB_WIDTH = (DATA_WIDTH/8),
    // Input ID field width (from AXI masters)
    parameter S_ID_WIDTH = 8,
    // Output ID field width (towards AXI slaves)
    // Additional bits required for response routing
    parameter M_ID_WIDTH = S_ID_WIDTH+$clog2(S_COUNT),
    // Propagate aruser signal
    parameter ARUSER_ENABLE = 0,
    // Width of aruser signal
    parameter ARUSER_WIDTH = 1,
    // Propagate ruser signal
    parameter RUSER_ENABLE = 0,
    // Width of ruser signal
    parameter RUSER_WIDTH = 1,
    // Number of concurrent unique IDs for each slave interface
    // S_COUNT concatenated fields of 32 bits
    parameter S_THREADS = {S_COUNT{32'd2}},
    // Number of concurrent operations for each slave interface
    // S_COUNT concatenated fields of 32 bits
    parameter S_ACCEPT = {S_COUNT{32'd16}},
    // Number of regions per master interface
    parameter M_REGIONS = 1,
    // Master interface base addresses
    // M_COUNT concatenated fields of M_REGIONS concatenated fields of ADDR_WIDTH bits
    // set to zero for default addressing based on M_ADDR_WIDTH
    parameter M_BASE_ADDR = 0,
    // Master interface address widths
    // M_COUNT concatenated fields of M_REGIONS concatenated fields of 32 bits
    parameter M_ADDR_WIDTH = {M_COUNT{{M_REGIONS{32'd24}}}},
    // Read connections between interfaces
    // M_COUNT concatenated fields of S_COUNT bits
    parameter M_CONNECT = {M_COUNT{{S_COUNT{1'b1}}}},
    // Number of concurrent operations for each master interface
    // M_COUNT concatenated fields of 32 bits
    parameter M_ISSUE = {M_COUNT{32'd4}},
    // Secure master (fail operations based on awprot/arprot)
    // M_COUNT bits
    parameter M_SECURE = {M_COUNT{1'b0}},
    // Slave interface AR channel register type (input)
    // 0 to bypass, 1 for simple buffer, 2 for skid buffer
    parameter S_AR_REG_TYPE = {S_COUNT{2'd0}},
    // Slave interface R channel register type (output)
    // 0 to bypass, 1 for simple buffer, 2 for skid buffer
    parameter S_R_REG_TYPE = {S_COUNT{2'd2}},
    // Master interface AR channel register type (output)
    // 0 to bypass, 1 for simple buffer, 2 for skid buffer
    parameter M_AR_REG_TYPE = {M_COUNT{2'd1}},
    // Master interface R channel register type (input)
    // 0 to bypass, 1 for simple buffer, 2 for skid buffer
    parameter M_R_REG_TYPE = {M_COUNT{2'd0}}
)
(
    input  wire                             clk,
    input  wire                             rst,

    /*
     * AXI slave interfaces
     */
    input  wire [S_COUNT*S_ID_WIDTH-1:0]    s_axi_arid,
    input  wire [S_COUNT*ADDR_WIDTH-1:0]    s_axi_araddr,
    input  wire [S_COUNT*8-1:0]             s_axi_arlen,
    input  wire [S_COUNT*3-1:0]             s_axi_arsize,
    input  wire [S_COUNT*2-1:0]             s_axi_arburst,
    input  wire [S_COUNT-1:0]               s_axi_arlock,
    input  wire [S_COUNT*4-1:0]             s_axi_arcache,
    input  wire [S_COUNT*3-1:0]             s_axi_arprot,
    input  wire [S_COUNT*4-1:0]             s_axi_arqos,
    input  wire [S_COUNT*ARUSER_WIDTH-1:0]  s_axi_aruser,
    input  wire [S_COUNT-1:0]               s_axi_arvalid,
    output wire [S_COUNT-1:0]               s_axi_arready,
    output wire [S_COUNT*S_ID_WIDTH-1:0]    s_axi_rid,
    output wire [S_COUNT*DATA_WIDTH-1:0]    s_axi_rdata,
    output wire [S_COUNT*2-1:0]             s_axi_rresp,
    output wire [S_COUNT-1:0]               s_axi_rlast,
    output wire [S_COUNT*RUSER_WIDTH-1:0]   s_axi_ruser,
    output wire [S_COUNT-1:0]               s_axi_rvalid,
    input  wire [S_COUNT-1:0]               s_axi_rready,

    /*
     * AXI master interfaces
     */
    output wire [M_COUNT*M_ID_WIDTH-1:0]    m_axi_arid,
    output wire [M_COUNT*ADDR_WIDTH-1:0]    m_axi_araddr,
    output wire [M_COUNT*8-1:0]             m_axi_arlen,
    output wire [M_COUNT*3-1:0]             m_axi_arsize,
    output wire [M_COUNT*2-1:0]             m_axi_arburst,
    output wire [M_COUNT-1:0]               m_axi_arlock,
    output wire [M_COUNT*4-1:0]             m_axi_arcache,
    output wire [M_COUNT*3-1:0]             m_axi_arprot,
    output wire [M_COUNT*4-1:0]             m_axi_arqos,
    output wire [M_COUNT*4-1:0]             m_axi_arregion,
    output wire [M_COUNT*ARUSER_WIDTH-1:0]  m_axi_aruser,
    output wire [M_COUNT-1:0]               m_axi_arvalid,
    input  wire [M_COUNT-1:0]               m_axi_arready,
    input  wire [M_COUNT*M_ID_WIDTH-1:0]    m_axi_rid,
    input  wire [M_COUNT*DATA_WIDTH-1:0]    m_axi_rdata,
    input  wire [M_COUNT*2-1:0]             m_axi_rresp,
    input  wire [M_COUNT-1:0]               m_axi_rlast,
    input  wire [M_COUNT*RUSER_WIDTH-1:0]   m_axi_ruser,
    input  wire [M_COUNT-1:0]               m_axi_rvalid,
    output wire [M_COUNT-1:0]               m_axi_rready
);

parameter CL_S_COUNT = $clog2(S_COUNT);
parameter CL_M_COUNT = $clog2(M_COUNT);
parameter M_COUNT_P1 = M_COUNT+1;
parameter CL_M_COUNT_P1 = $clog2(M_COUNT_P1);

integer i;

// check configuration
initial begin
    if (M_ID_WIDTH < S_ID_WIDTH+$clog2(S_COUNT)) begin
        $error("Error: M_ID_WIDTH must be at least $clog2(S_COUNT) larger than S_ID_WIDTH (instance %m)");
        $finish;
    end

    for (i = 0; i < M_COUNT*M_REGIONS; i = i + 1) begin
        if (M_ADDR_WIDTH[i*32 +: 32] && (M_ADDR_WIDTH[i*32 +: 32] < 12 || M_ADDR_WIDTH[i*32 +: 32] > ADDR_WIDTH)) begin
            $error("Error: value out of range (instance %m)");
            $finish;
        end
    end
end

wire [S_COUNT*S_ID_WIDTH-1:0]    int_s_axi_arid;
wire [S_COUNT*ADDR_WIDTH-1:0]    int_s_axi_araddr;
wire [S_COUNT*8-1:0]             int_s_axi_arlen;
wire [S_COUNT*3-1:0]             int_s_axi_arsize;
wire [S_COUNT*2-1:0]             int_s_axi_arburst;
wire [S_COUNT-1:0]               int_s_axi_arlock;
wire [S_COUNT*4-1:0]             int_s_axi_arcache;
wire [S_COUNT*3-1:0]             int_s_axi_arprot;
wire [S_COUNT*4-1:0]             int_s_axi_arqos;
wire [S_COUNT*4-1:0]             int_s_axi_arregion;
wire [S_COUNT*ARUSER_WIDTH-1:0]  int_s_axi_aruser;
wire [S_COUNT-1:0]               int_s_axi_arvalid;
wire [S_COUNT-1:0]               int_s_axi_arready;

wire [S_COUNT*M_COUNT-1:0]       int_axi_arvalid;
wire [M_COUNT*S_COUNT-1:0]       int_axi_arready;

wire [M_COUNT*M_ID_WIDTH-1:0]    int_m_axi_rid;
wire [M_COUNT*DATA_WIDTH-1:0]    int_m_axi_rdata;
wire [M_COUNT*2-1:0]             int_m_axi_rresp;
wire [M_COUNT-1:0]               int_m_axi_rlast;
wire [M_COUNT*RUSER_WIDTH-1:0]   int_m_axi_ruser;
wire [M_COUNT-1:0]               int_m_axi_rvalid;
wire [M_COUNT-1:0]               int_m_axi_rready;

wire [M_COUNT*S_COUNT-1:0]       int_axi_rvalid;
wire [S_COUNT*M_COUNT-1:0]       int_axi_rready;

generate

    genvar m, n;

    for (m = 0; m < S_COUNT; m = m + 1) begin : s_ifaces
        // address decode and admission control
        wire [CL_M_COUNT-1:0] a_select;

        wire m_axi_avalid;
        wire m_axi_aready;

        wire m_rc_decerr;
        wire m_rc_valid;
        wire m_rc_ready;

        wire [S_ID_WIDTH-1:0] s_cpl_id;
        wire s_cpl_valid;

        axi_crossbar_addr #(
            .S(m),
            .S_COUNT(S_COUNT),
            .M_COUNT(M_COUNT),
            .ADDR_WIDTH(ADDR_WIDTH),
            .ID_WIDTH(S_ID_WIDTH),
            .S_THREADS(S_THREADS[m*32 +: 32]),
            .S_ACCEPT(S_ACCEPT[m*32 +: 32]),
            .M_REGIONS(M_REGIONS),
            .M_BASE_ADDR(M_BASE_ADDR),
            .M_ADDR_WIDTH(M_ADDR_WIDTH),
            .M_CONNECT(M_CONNECT),
            .M_SECURE(M_SECURE),
            .WC_OUTPUT(0)
        )
        addr_inst (
            .clk(clk),
            .rst(rst),

            /*
             * Address input
             */
            .s_axi_aid(int_s_axi_arid[m*S_ID_WIDTH +: S_ID_WIDTH]),
            .s_axi_aaddr(int_s_axi_araddr[m*ADDR_WIDTH +: ADDR_WIDTH]),
            .s_axi_aprot(int_s_axi_arprot[m*3 +: 3]),
            .s_axi_aqos(int_s_axi_arqos[m*4 +: 4]),
            .s_axi_avalid(int_s_axi_arvalid[m]),
            .s_axi_aready(int_s_axi_arready[m]),

            /*
             * Address output
             */
            .m_axi_aregion(int_s_axi_arregion[m*4 +: 4]),
            .m_select(a_select),
            .m_axi_avalid(m_axi_avalid),
            .m_axi_aready(m_axi_aready),

            /*
             * Write command output
             */
            .m_wc_select(),
            .m_wc_decerr(),
            .m_wc_valid(),
            .m_wc_ready(1'b1),

            /*
             * Response command output
             */
            .m_rc_decerr(m_rc_decerr),
            .m_rc_valid(m_rc_valid),
            .m_rc_ready(m_rc_ready),

            /*
             * Completion input
             */
            .s_cpl_id(s_cpl_id),
            .s_cpl_valid(s_cpl_valid)
        );

        assign int_axi_arvalid[m*M_COUNT +: M_COUNT] = m_axi_avalid << a_select;
        assign m_axi_aready = int_axi_arready[a_select*S_COUNT+m];

        // decode error handling
        reg [S_ID_WIDTH-1:0]  decerr_m_axi_rid_reg = {S_ID_WIDTH{1'b0}}, decerr_m_axi_rid_next;
        reg                   decerr_m_axi_rlast_reg = 1'b0, decerr_m_axi_rlast_next;
        reg                   decerr_m_axi_rvalid_reg = 1'b0, decerr_m_axi_rvalid_next;
        wire                  decerr_m_axi_rready;

        reg [7:0] decerr_len_reg = 8'd0, decerr_len_next;

        assign m_rc_ready = !decerr_m_axi_rvalid_reg;

        always @* begin
            decerr_len_next = decerr_len_reg;
            decerr_m_axi_rid_next = decerr_m_axi_rid_reg;
            decerr_m_axi_rlast_next = decerr_m_axi_rlast_reg;
            decerr_m_axi_rvalid_next = decerr_m_axi_rvalid_reg;

            if (decerr_m_axi_rvalid_reg) begin
                if (decerr_m_axi_rready) begin
                    if (decerr_len_reg > 0) begin
                        decerr_len_next = decerr_len_reg-1;
                        decerr_m_axi_rlast_next = (decerr_len_next == 0);
                        decerr_m_axi_rvalid_next = 1'b1;
                    end else begin
                        decerr_m_axi_rvalid_next = 1'b0;
                    end
                end
            end else if (m_rc_valid && m_rc_ready) begin
                decerr_len_next = int_s_axi_arlen[m*8 +: 8];
                decerr_m_axi_rid_next = int_s_axi_arid[m*S_ID_WIDTH +: S_ID_WIDTH];
                decerr_m_axi_rlast_next = (decerr_len_next == 0);
                decerr_m_axi_rvalid_next = 1'b1;
            end
        end

        always @(posedge clk) begin
            if (rst) begin
                decerr_m_axi_rvalid_reg <= 1'b0;
            end else begin
                decerr_m_axi_rvalid_reg <= decerr_m_axi_rvalid_next;
            end

            decerr_m_axi_rid_reg <= decerr_m_axi_rid_next;
            decerr_m_axi_rlast_reg <= decerr_m_axi_rlast_next;
            decerr_len_reg <= decerr_len_next;
        end

        // read response arbitration
        wire [M_COUNT_P1-1:0] r_request;
        wire [M_COUNT_P1-1:0] r_acknowledge;
        wire [M_COUNT_P1-1:0] r_grant;
        wire r_grant_valid;
        wire [CL_M_COUNT_P1-1:0] r_grant_encoded;

        arbiter #(
            .PORTS(M_COUNT_P1),
            .ARB_TYPE_ROUND_ROBIN(1),
            .ARB_BLOCK(1),
            .ARB_BLOCK_ACK(1),
            .ARB_LSB_HIGH_PRIORITY(1)
        )
        r_arb_inst (
            .clk(clk),
            .rst(rst),
            .request(r_request),
            .acknowledge(r_acknowledge),
            .grant(r_grant),
            .grant_valid(r_grant_valid),
            .grant_encoded(r_grant_encoded)
        );

        // read response mux
        wire [S_ID_WIDTH-1:0]  m_axi_rid_mux    = {decerr_m_axi_rid_reg, int_m_axi_rid} >> r_grant_encoded*M_ID_WIDTH;
        wire [DATA_WIDTH-1:0]  m_axi_rdata_mux  = {{DATA_WIDTH{1'b0}}, int_m_axi_rdata} >> r_grant_encoded*DATA_WIDTH;
        wire [1:0]             m_axi_rresp_mux  = {2'b11, int_m_axi_rresp} >> r_grant_encoded*2;
        wire                   m_axi_rlast_mux  = {decerr_m_axi_rlast_reg, int_m_axi_rlast} >> r_grant_encoded;
        wire [RUSER_WIDTH-1:0] m_axi_ruser_mux  = {{RUSER_WIDTH{1'b0}}, int_m_axi_ruser} >> r_grant_encoded*RUSER_WIDTH;
        wire                   m_axi_rvalid_mux = ({decerr_m_axi_rvalid_reg, int_m_axi_rvalid} >> r_grant_encoded) & r_grant_valid;
        wire                   m_axi_rready_mux;

        assign int_axi_rready[m*M_COUNT +: M_COUNT] = (r_grant_valid && m_axi_rready_mux) << r_grant_encoded;
        assign decerr_m_axi_rready = (r_grant_valid && m_axi_rready_mux) && (r_grant_encoded == M_COUNT_P1-1);

        for (n = 0; n < M_COUNT; n = n + 1) begin
            assign r_request[n] = int_axi_rvalid[n*S_COUNT+m] && !r_grant[n];
            assign r_acknowledge[n] = r_grant[n] && int_axi_rvalid[n*S_COUNT+m] && m_axi_rlast_mux && m_axi_rready_mux;
        end

        assign r_request[M_COUNT_P1-1] = decerr_m_axi_rvalid_reg && !r_grant[M_COUNT_P1-1];
        assign r_acknowledge[M_COUNT_P1-1] = r_grant[M_COUNT_P1-1] && decerr_m_axi_rvalid_reg && decerr_m_axi_rlast_reg && m_axi_rready_mux;

        assign s_cpl_id = m_axi_rid_mux;
        assign s_cpl_valid = m_axi_rvalid_mux && m_axi_rready_mux && m_axi_rlast_mux;

        // S side register
        axi_register_rd #(
            .DATA_WIDTH(DATA_WIDTH),
            .ADDR_WIDTH(ADDR_WIDTH),
            .STRB_WIDTH(STRB_WIDTH),
            .ID_WIDTH(S_ID_WIDTH),
            .ARUSER_ENABLE(ARUSER_ENABLE),
            .ARUSER_WIDTH(ARUSER_WIDTH),
            .RUSER_ENABLE(RUSER_ENABLE),
            .RUSER_WIDTH(RUSER_WIDTH),
            .AR_REG_TYPE(S_AR_REG_TYPE[m*2 +: 2]),
            .R_REG_TYPE(S_R_REG_TYPE[m*2 +: 2])
        )
        reg_inst (
            .clk(clk),
            .rst(rst),
            .s_axi_arid(s_axi_arid[m*S_ID_WIDTH +: S_ID_WIDTH]),
            .s_axi_araddr(s_axi_araddr[m*ADDR_WIDTH +: ADDR_WIDTH]),
            .s_axi_arlen(s_axi_arlen[m*8 +: 8]),
            .s_axi_arsize(s_axi_arsize[m*3 +: 3]),
            .s_axi_arburst(s_axi_arburst[m*2 +: 2]),
            .s_axi_arlock(s_axi_arlock[m]),
            .s_axi_arcache(s_axi_arcache[m*4 +: 4]),
            .s_axi_arprot(s_axi_arprot[m*3 +: 3]),
            .s_axi_arqos(s_axi_arqos[m*4 +: 4]),
            .s_axi_arregion(4'd0),
            .s_axi_aruser(s_axi_aruser[m*ARUSER_WIDTH +: ARUSER_WIDTH]),
            .s_axi_arvalid(s_axi_arvalid[m]),
            .s_axi_arready(s_axi_arready[m]),
            .s_axi_rid(s_axi_rid[m*S_ID_WIDTH +: S_ID_WIDTH]),
            .s_axi_rdata(s_axi_rdata[m*DATA_WIDTH +: DATA_WIDTH]),
            .s_axi_rresp(s_axi_rresp[m*2 +: 2]),
            .s_axi_rlast(s_axi_rlast[m]),
            .s_axi_ruser(s_axi_ruser[m*RUSER_WIDTH +: RUSER_WIDTH]),
            .s_axi_rvalid(s_axi_rvalid[m]),
            .s_axi_rready(s_axi_rready[m]),
            .m_axi_arid(int_s_axi_arid[m*S_ID_WIDTH +: S_ID_WIDTH]),
            .m_axi_araddr(int_s_axi_araddr[m*ADDR_WIDTH +: ADDR_WIDTH]),
            .m_axi_arlen(int_s_axi_arlen[m*8 +: 8]),
            .m_axi_arsize(int_s_axi_arsize[m*3 +: 3]),
            .m_axi_arburst(int_s_axi_arburst[m*2 +: 2]),
            .m_axi_arlock(int_s_axi_arlock[m]),
            .m_axi_arcache(int_s_axi_arcache[m*4 +: 4]),
            .m_axi_arprot(int_s_axi_arprot[m*3 +: 3]),
            .m_axi_arqos(int_s_axi_arqos[m*4 +: 4]),
            .m_axi_arregion(),
            .m_axi_aruser(int_s_axi_aruser[m*ARUSER_WIDTH +: ARUSER_WIDTH]),
            .m_axi_arvalid(int_s_axi_arvalid[m]),
            .m_axi_arready(int_s_axi_arready[m]),
            .m_axi_rid(m_axi_rid_mux),
            .m_axi_rdata(m_axi_rdata_mux),
            .m_axi_rresp(m_axi_rresp_mux),
            .m_axi_rlast(m_axi_rlast_mux),
            .m_axi_ruser(m_axi_ruser_mux),
            .m_axi_rvalid(m_axi_rvalid_mux),
            .m_axi_rready(m_axi_rready_mux)
        );
    end // s_ifaces

    for (n = 0; n < M_COUNT; n = n + 1) begin : m_ifaces
        // in-flight transaction count
        wire trans_start;
        wire trans_complete;
        reg [$clog2(M_ISSUE[n*32 +: 32]+1)-1:0] trans_count_reg = 0;

        wire trans_limit = trans_count_reg >= M_ISSUE[n*32 +: 32] && !trans_complete;

        always @(posedge clk) begin
            if (rst) begin
                trans_count_reg <= 0;
            end else begin
                if (trans_start && !trans_complete) begin
                    trans_count_reg <= trans_count_reg + 1;
                end else if (!trans_start && trans_complete) begin
                    trans_count_reg <= trans_count_reg - 1;
                end
            end
        end

        // address arbitration
        wire [S_COUNT-1:0] a_request;
        wire [S_COUNT-1:0] a_acknowledge;
        wire [S_COUNT-1:0] a_grant;
        wire a_grant_valid;
        wire [CL_S_COUNT-1:0] a_grant_encoded;

        arbiter #(
            .PORTS(S_COUNT),
            .ARB_TYPE_ROUND_ROBIN(1),
            .ARB_BLOCK(1),
            .ARB_BLOCK_ACK(1),
            .ARB_LSB_HIGH_PRIORITY(1)
        )
        a_arb_inst (
            .clk(clk),
            .rst(rst),
            .request(a_request),
            .acknowledge(a_acknowledge),
            .grant(a_grant),
            .grant_valid(a_grant_valid),
            .grant_encoded(a_grant_encoded)
        );

        // address mux
        wire [M_ID_WIDTH-1:0]   s_axi_arid_mux     = int_s_axi_arid[a_grant_encoded*S_ID_WIDTH +: S_ID_WIDTH] | (a_grant_encoded << S_ID_WIDTH);
        wire [ADDR_WIDTH-1:0]   s_axi_araddr_mux   = int_s_axi_araddr[a_grant_encoded*ADDR_WIDTH +: ADDR_WIDTH];
        wire [7:0]              s_axi_arlen_mux    = int_s_axi_arlen[a_grant_encoded*8 +: 8];
        wire [2:0]              s_axi_arsize_mux   = int_s_axi_arsize[a_grant_encoded*3 +: 3];
        wire [1:0]              s_axi_arburst_mux  = int_s_axi_arburst[a_grant_encoded*2 +: 2];
        wire                    s_axi_arlock_mux   = int_s_axi_arlock[a_grant_encoded];
        wire [3:0]              s_axi_arcache_mux  = int_s_axi_arcache[a_grant_encoded*4 +: 4];
        wire [2:0]              s_axi_arprot_mux   = int_s_axi_arprot[a_grant_encoded*3 +: 3];
        wire [3:0]              s_axi_arqos_mux    = int_s_axi_arqos[a_grant_encoded*4 +: 4];
        wire [3:0]              s_axi_arregion_mux = int_s_axi_arregion[a_grant_encoded*4 +: 4];
        wire [ARUSER_WIDTH-1:0] s_axi_aruser_mux   = int_s_axi_aruser[a_grant_encoded*ARUSER_WIDTH +: ARUSER_WIDTH];
        wire                    s_axi_arvalid_mux  = int_axi_arvalid[a_grant_encoded*M_COUNT+n] && a_grant_valid;
        wire                    s_axi_arready_mux;

        assign int_axi_arready[n*S_COUNT +: S_COUNT] = (a_grant_valid && s_axi_arready_mux) << a_grant_encoded;

        for (m = 0; m < S_COUNT; m = m + 1) begin
            assign a_request[m] = int_axi_arvalid[m*M_COUNT+n] && !a_grant[m] && !trans_limit;
            assign a_acknowledge[m] = a_grant[m] && int_axi_arvalid[m*M_COUNT+n] && s_axi_arready_mux;
        end

        assign trans_start = s_axi_arvalid_mux && s_axi_arready_mux && a_grant_valid;

        // read response forwarding
        wire [CL_S_COUNT-1:0] r_select = m_axi_rid[n*M_ID_WIDTH +: M_ID_WIDTH] >> S_ID_WIDTH;

        assign int_axi_rvalid[n*S_COUNT +: S_COUNT] = int_m_axi_rvalid[n] << r_select;
        assign int_m_axi_rready[n] = int_axi_rready[r_select*M_COUNT+n];

        assign trans_complete = int_m_axi_rvalid[n] && int_m_axi_rready[n] && int_m_axi_rlast[n];

        // M side register
        axi_register_rd #(
            .DATA_WIDTH(DATA_WIDTH),
            .ADDR_WIDTH(ADDR_WIDTH),
            .STRB_WIDTH(STRB_WIDTH),
            .ID_WIDTH(M_ID_WIDTH),
            .ARUSER_ENABLE(ARUSER_ENABLE),
            .ARUSER_WIDTH(ARUSER_WIDTH),
            .RUSER_ENABLE(RUSER_ENABLE),
            .RUSER_WIDTH(RUSER_WIDTH),
            .AR_REG_TYPE(M_AR_REG_TYPE[n*2 +: 2]),
            .R_REG_TYPE(M_R_REG_TYPE[n*2 +: 2])
        )
        reg_inst (
            .clk(clk),
            .rst(rst),
            .s_axi_arid(s_axi_arid_mux),
            .s_axi_araddr(s_axi_araddr_mux),
            .s_axi_arlen(s_axi_arlen_mux),
            .s_axi_arsize(s_axi_arsize_mux),
            .s_axi_arburst(s_axi_arburst_mux),
            .s_axi_arlock(s_axi_arlock_mux),
            .s_axi_arcache(s_axi_arcache_mux),
            .s_axi_arprot(s_axi_arprot_mux),
            .s_axi_arqos(s_axi_arqos_mux),
            .s_axi_arregion(s_axi_arregion_mux),
            .s_axi_aruser(s_axi_aruser_mux),
            .s_axi_arvalid(s_axi_arvalid_mux),
            .s_axi_arready(s_axi_arready_mux),
            .s_axi_rid(int_m_axi_rid[n*M_ID_WIDTH +: M_ID_WIDTH]),
            .s_axi_rdata(int_m_axi_rdata[n*DATA_WIDTH +: DATA_WIDTH]),
            .s_axi_rresp(int_m_axi_rresp[n*2 +: 2]),
            .s_axi_rlast(int_m_axi_rlast[n]),
            .s_axi_ruser(int_m_axi_ruser[n*RUSER_WIDTH +: RUSER_WIDTH]),
            .s_axi_rvalid(int_m_axi_rvalid[n]),
            .s_axi_rready(int_m_axi_rready[n]),
            .m_axi_arid(m_axi_arid[n*M_ID_WIDTH +: M_ID_WIDTH]),
            .m_axi_araddr(m_axi_araddr[n*ADDR_WIDTH +: ADDR_WIDTH]),
            .m_axi_arlen(m_axi_arlen[n*8 +: 8]),
            .m_axi_arsize(m_axi_arsize[n*3 +: 3]),
            .m_axi_arburst(m_axi_arburst[n*2 +: 2]),
            .m_axi_arlock(m_axi_arlock[n]),
            .m_axi_arcache(m_axi_arcache[n*4 +: 4]),
            .m_axi_arprot(m_axi_arprot[n*3 +: 3]),
            .m_axi_arqos(m_axi_arqos[n*4 +: 4]),
            .m_axi_arregion(m_axi_arregion[n*4 +: 4]),
            .m_axi_aruser(m_axi_aruser[n*ARUSER_WIDTH +: ARUSER_WIDTH]),
            .m_axi_arvalid(m_axi_arvalid[n]),
            .m_axi_arready(m_axi_arready[n]),
            .m_axi_rid(m_axi_rid[n*M_ID_WIDTH +: M_ID_WIDTH]),
            .m_axi_rdata(m_axi_rdata[n*DATA_WIDTH +: DATA_WIDTH]),
            .m_axi_rresp(m_axi_rresp[n*2 +: 2]),
            .m_axi_rlast(m_axi_rlast[n]),
            .m_axi_ruser(m_axi_ruser[n*RUSER_WIDTH +: RUSER_WIDTH]),
            .m_axi_rvalid(m_axi_rvalid[n]),
            .m_axi_rready(m_axi_rready[n])
        );
    end // m_ifaces

endgenerate

endmodule