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////////////////////////////////////////////////////////////////////////////////
//
// Filename: 	fastmaster.v
//
// Project:	OpenArty, an entirely open SoC based upon the Arty platform
//
// Purpose:	On other projects, this file would be called the "bus
//		interconnect".  This module connects all the devices on the
//	Wishbone bus within this project together.  It is created by hand, not
//	automatically.
//
// Creator:	Dan Gisselquist, Ph.D.
//		Gisselquist Technology, LLC
//
////////////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2015-2016, Gisselquist Technology, LLC
//
// This program is free software (firmware): you can redistribute it and/or
// modify it under the terms of  the GNU General Public License as published
// by the Free Software Foundation, either version 3 of the License, or (at
// your option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program.  (It's in the $(ROOT)/doc directory, run make with no
// target there if the PDF file isn't present.)  If not, see
// <http://www.gnu.org/licenses/> for a copy.
//
// License:	GPL, v3, as defined and found on www.gnu.org,
//		http://www.gnu.org/licenses/gpl.html
//
//
////////////////////////////////////////////////////////////////////////////////
//
//
`define	NO_ZIP_WBU_DELAY
// `define	ZIPCPU
`ifdef	ZIPCPU
`define	ZIP_SYSTEM
`ifndef	ZIP_SYSTEM
`define	ZIP_BONES
`endif	// ZIP_SYSTEM
`endif	// ZipCPU
//
//
`define	SDCARD_ACCESS
`define	ETHERNET_ACCESS
`ifndef	VERILATOR
`define	ICAPE_ACCESS
`endif
`define	FLASH_ACCESS
// `define	SDRAM_ACCESS
`define	GPS_CLOCK
//	UART_ACCESS and GPS_UART have both been placed within fastio
//		`define	UART_ACCESS
//		`define	GPS_UART
`define	RTC_ACCESS
`define	OLEDRGB_ACCESS
//
`ifdef	FLASH_ACCESS
`define	FLASH_SCOPE	// Position zero
`else
`ifdef ZIPCPU
// `define	CPU_SCOPE	// Position zero
`endif
`endif
// `define	GPS_SCOPE	// Position one
`ifdef ICAPE_ACCESS
`define	CFG_SCOPE	// Position one
`endif
`ifdef	SDRAM_ACCESS
// `define	SDRAM_SCOPE		// Position two
`endif
// `define	ENET_SCOPE
//
//
module	fastmaster(i_clk, i_rst,
		// CNC
		i_rx_stb, i_rx_data, o_tx_stb, o_tx_data, i_tx_busy,
		// Boad I/O
		i_sw, i_btn, o_led,
		o_clr_led0, o_clr_led1, o_clr_led2, o_clr_led3,
		// PMod I/O
		i_aux_rx, o_aux_tx, o_aux_cts, i_gps_rx, o_gps_tx,
		// The Quad SPI Flash
		o_qspi_cs_n, o_qspi_sck, o_qspi_dat, i_qspi_dat, o_qspi_mod,
		// The DDR3 SDRAM
		o_ddr_reset_n, o_ddr_cke, o_ddr_bus_oe,
		o_ddr_cmd_a, o_ddr_cmd_b, o_ddr_data, i_ddr_data,
		// The SD Card
		o_sd_sck, o_sd_cmd, o_sd_data, i_sd_cmd, i_sd_data, i_sd_detect,
		// Ethernet control (MDIO) lines
		o_mdclk, o_mdio, o_mdwe, i_mdio,
		// OLED Control interface (roughly SPI)
		o_oled_sck, o_oled_cs_n, o_oled_mosi, o_oled_dcn,
		o_oled_reset_n, o_oled_vccen, o_oled_pmoden,
		// The GPS PMod
		i_gps_pps, i_gps_3df
		);
	parameter	ZA=24, ZIPINTS=13;
	input	i_clk, i_rst;
	// The bus commander, via an external uart port
	input			i_rx_stb;
	input		[7:0]	i_rx_data;
	output	wire		o_tx_stb;
	output	wire	[7:0]	o_tx_data;
	input			i_tx_busy;
	// I/O to/from board level devices
	input		[3:0]	i_sw;	// 16 switch bus
	input		[3:0]	i_btn;	// 5 Buttons
	output	wire	[3:0]	o_led;	// 16 wide LED's
	output	wire	[2:0]	o_clr_led0, o_clr_led1, o_clr_led2, o_clr_led3;
	// PMod UARTs
	input			i_aux_rx;
	output	wire		o_aux_tx, o_aux_cts;
	input			i_gps_rx;
	output	wire		o_gps_tx;
	// Quad-SPI flash control
	output	wire		o_qspi_cs_n, o_qspi_sck;
	output	wire	[3:0]	o_qspi_dat;
	input		[3:0]	i_qspi_dat;
	output	wire	[1:0]	o_qspi_mod;
	// DDR3 RAM controller
	output	wire		o_ddr_reset_n, o_ddr_cke, o_ddr_bus_oe;
	output	wire	[26:0]	o_ddr_cmd_a, o_ddr_cmd_b;
	output	wire	[63:0]	o_ddr_data;
	input		[63:0]	i_ddr_data;
	// The SD Card
	output	wire		o_sd_sck;
	output	wire		o_sd_cmd;
	output	wire	[3:0]	o_sd_data;
	input			i_sd_cmd;
	input		[3:0]	i_sd_data;
	input			i_sd_detect;
	// Ethernet control (MDIO)
	output	wire		o_mdclk, o_mdio, o_mdwe;
	input			i_mdio;
	// OLEDRGB interface
	output	wire		o_oled_sck, o_oled_cs_n, o_oled_mosi,
				o_oled_dcn, o_oled_reset_n, o_oled_vccen,
				o_oled_pmoden;
	// GPS PMod (GPS UART above)
	input			i_gps_pps;
	input			i_gps_3df;
 
	//
	//
	// Master wishbone wires
	//
	//
	wire		wb_cyc, wb_stb, wb_we, wb_stall, wb_err;
	wire	[31:0]	wb_data, wb_addr;
	reg		wb_ack;
	reg	[31:0]	wb_idata;
 
	// Interrupts
	wire		gpio_int, oled_int, flash_int, scop_int;
	wire		enet_tx_int, enet_rx_int, sdcard_int, rtc_int, rtc_pps,
			auxrx_int, auxtx_int, gpsrx_int, sw_int, btn_int;
 
	//
	//
	// First BUS master source: The UART
	//
	//
	wire	[31:0]	dwb_idata;
 
	// Wires going to devices
	wire		wbu_cyc, wbu_stb, wbu_we;
	wire	[31:0]	wbu_addr, wbu_data;
	// and then coming from devices
	wire		wbu_ack, wbu_stall, wbu_err;
	wire	[31:0]	wbu_idata;
	// And then headed back home
	wire	w_interrupt;
	// Oh, and the debug control for the ZIP CPU
	wire		wbu_zip_sel, zip_dbg_ack, zip_dbg_stall;
	wire	[31:0]	zip_dbg_data;
	wbubus	genbus(i_clk, i_rx_stb, i_rx_data,
			wbu_cyc, wbu_stb, wbu_we, wbu_addr, wbu_data,
			(wbu_zip_sel)?zip_dbg_ack:wbu_ack,
			(wbu_zip_sel)?zip_dbg_stall:wbu_stall,
				wbu_err,
				(wbu_zip_sel)?zip_dbg_data:wbu_idata,
			w_interrupt,
			o_tx_stb, o_tx_data, i_tx_busy);
 
	// assign	o_dbg = (wbu_ack)&&(wbu_cyc);
 
	wire	zip_cpu_int; // True if the CPU suddenly halts
`ifdef	ZIPCPU
	// Are we trying to access the ZipCPU?  Such accesses must be special,
	// because they must succeed regardless of whether or not the ZipCPU
	// is on the bus.  Hence, we trap them here.
	assign	wbu_zip_sel = (wbu_addr[27]);
 
	//
	//
	// Second BUS master source: The ZipCPU
	//
	//
	wire		zip_cyc, zip_stb, zip_we;
	wire	[(ZA-1):0]	w_zip_addr;
	wire	[31:0]	zip_data, zip_scope_data;
	// and then coming from devices
	wire		zip_ack, zip_stall, zip_err;
 
`ifdef	ZIP_SYSTEM
	wire	[(ZIPINTS-1):0]	zip_interrupt_vec = {
		// Lazy(ier) interrupts
		oled_int, gpio_int, rtc_int, scop_int, flash_int, sw_int, btn_int,
		// Fast interrupts
		sdcard_int, auxtx_int, auxrx_int, enet_tx_int, enet_rx_int,
			gpsrx_int, rtc_pps
		};
 
	zipsystem #(	.RESET_ADDRESS(24'h0480000),
			.ADDRESS_WIDTH(ZA),
			.LGICACHE(10),
			.START_HALTED(0),
			.EXTERNAL_INTERRUPTS(ZIPINTS),
			.HIGHSPEED_CPU(0))
		zippy(i_clk, i_rst,
			// Zippys wishbone interface
			zip_cyc, zip_stb, zip_we, w_zip_addr, zip_data,
				zip_ack, zip_stall, dwb_idata, zip_err,
			zip_interrupt_vec, zip_cpu_int,
			// Debug wishbone interface
			((wbu_cyc)&&(wbu_zip_sel)),
				((wbu_stb)&&(wbu_zip_sel)),wbu_we, wbu_addr[0],
				wbu_data,
				zip_dbg_ack, zip_dbg_stall, zip_dbg_data
`ifdef	CPU_DEBUG
			, zip_scope_data
`endif
			);
`else // ZIP_SYSTEM
	wire	w_zip_cpu_int_ignored;
	zipbones #(	.RESET_ADDRESS(24'h08000),
			.ADDRESS_WIDTH(ZA),
			.LGICACHE(10),
			.START_HALTED(1),
			.HIGHSPEED_CPU(1))
		zippy(i_clk, i_rst,
			// Zippys wishbone interface
			zip_cyc, zip_stb, zip_we, w_zip_addr, zip_data,
				zip_ack, zip_stall, dwb_idata, zip_err,
			w_interrupt, w_zip_cpu_int_ignored,
			// Debug wishbone interface
			((wbu_cyc)&&(wbu_zip_sel)),
				((wbu_stb)&&(wbu_zip_sel)),wbu_we, wbu_addr[0],
				wbu_data,
				zip_dbg_ack, zip_dbg_stall, zip_dbg_data
`ifdef	CPU_DEBUG
			, zip_scope_data
`endif
			);
	assign	zip_cpu_int = 1'b0;
`endif	// ZIP_SYSTEM v ZIP_BONES
 
	wire [31:0]	zip_addr;
	generate
	if (ZA < 32)
		assign	zip_addr = { {(32-ZA){1'b0}}, w_zip_addr};
	else
		assign	zip_addr = w_zip_addr;
	endgenerate
 
	//
	//
	// And an arbiter to decide who gets to access the bus
	//
	//
	wire	dwb_we, dwb_stb, dwb_cyc, dwb_ack, dwb_stall, dwb_err;
	wire	[31:0]	dwb_addr, dwb_odata;
	wbpriarbiter #(32,32) wbu_zip_arbiter(i_clk,
		// The ZIP CPU Master -- Gets the priority slot
		zip_cyc, zip_stb, zip_we, zip_addr, zip_data,
			zip_ack, zip_stall, zip_err,
		// The UART interface Master
		(wbu_cyc)&&(~wbu_zip_sel), (wbu_stb)&&(~wbu_zip_sel), wbu_we,
			wbu_addr, wbu_data,
			wbu_ack, wbu_stall, wbu_err,
		// Common bus returns
		dwb_cyc, dwb_stb, dwb_we, dwb_addr, dwb_odata,
			dwb_ack, dwb_stall, dwb_err);
 
	// 
	// 
	// And because the ZIP CPU and the Arbiter create an unacceptable
	// delay, we fail timing.  So we add in a delay cycle ...
	// 
	// 
	assign	wbu_idata = dwb_idata;
	busdelay	wbu_zip_delay(i_clk,
			dwb_cyc, dwb_stb, dwb_we, dwb_addr, dwb_odata,
				dwb_ack, dwb_stall, dwb_idata, dwb_err,
			wb_cyc, wb_stb, wb_we, wb_addr, wb_data,
				wb_ack, wb_stall, wb_idata, wb_err);
 
`else	// ZIPCPU
	assign	zip_cpu_int = 1'b0; // No CPU here to halt
	assign	wbu_zip_sel = 1'b0;
 
	// If there's no ZipCPU, there's no need for a Zip/WB-Uart bus delay.
	// We can go directly from the WB-Uart master bus to the master bus
	// itself.
	assign	wb_cyc    = wbu_cyc;
	assign	wb_stb    = wbu_stb;
	assign	wb_we     = wbu_we;
	assign	wb_addr   = wbu_addr;
	assign	wb_data   = wbu_data;
	assign	wbu_idata = wb_idata;
	assign	wbu_ack   = wb_ack;
	assign	wbu_stall = wb_stall;
	assign	wbu_err   = wb_err;
 
	// The CPU never halts if it doesn't exist, so set this interrupt to
	// zero.
	assign	zip_cpu_int= 1'b0;
`endif	// ZIPCPU
 
 
	//
	// Peripheral select lines.
	//
	// These lines will be true during any wishbone cycle whose address
	// line selects the given I/O peripheral.  The none_sel and many_sel
	// lines are used to detect problems, such as when no device is
	// selected or many devices are selected.  Such problems will lead to
	// bus errors (below).
	//
	wire	io_sel, scop_sel, netb_sel,
			flctl_sel, rtc_sel, sdcard_sel, netp_sel,
			oled_sel, gps_sel, mio_sel, cfg_sel,
			mem_sel, flash_sel, ram_sel,
			none_sel, many_sel;
 
	wire	[4:0]	skipaddr;
	assign	skipaddr = { wb_addr[26], wb_addr[22], wb_addr[15], wb_addr[11],
				~wb_addr[8] };
	assign	ram_sel   = (skipaddr[4]);
	assign	flash_sel = (skipaddr[4:3]==2'b01);
	assign	mem_sel   = (skipaddr[4:2]==3'b001);
	assign	netb_sel  = (skipaddr[4:1]==4'b0001);
	assign	io_sel    = (~|skipaddr)&&(wb_addr[7:5]==3'b000);
	assign	scop_sel  = (~|skipaddr)&&(wb_addr[7:3]==5'b0010_0);
	assign	rtc_sel   = (~|skipaddr)&&(wb_addr[7:2]==6'b0010_10);
	assign	sdcard_sel= (~|skipaddr)&&(wb_addr[7:2]==6'b0010_11);
	//assign gps_sel  = (~|skipaddr)&&(wb_addr[7:2]==6'b0011_00);
	assign	oled_sel  = (~|skipaddr)&&(wb_addr[7:2]==6'b0011_01);
	assign	netp_sel  = (~|skipaddr)&&(wb_addr[7:3]==5'b0011_1);
	assign	gps_sel   = (~|skipaddr)&&(	(wb_addr[7:2]==6'b0011_00)
					    ||	(wb_addr[7:3]==5'b0100_0));
	assign	mio_sel   = (~|skipaddr)&&(wb_addr[7:5]==3'b101);
	assign	flctl_sel = (~|skipaddr)&&(wb_addr[7:5]==3'b110);
	assign	cfg_sel   = (~|skipaddr)&&(wb_addr[7:5]==3'b111);
 
	wire	skiperr;
	assign	skiperr = (|wb_addr[31:27])
				||(~skipaddr[4])&&(|wb_addr[25:23])
				||(skipaddr[4:3]==2'b00)&&(|wb_addr[21:16])
				||(skipaddr[4:2]==3'b000)&&(|wb_addr[14:12])
				||(skipaddr[4:1]==4'b0000)&&(|wb_addr[10:9]);
 
 
	//
	// Peripheral acknowledgement lines
	//
	// These are only a touch more confusing, since the flash device will
	// ACK for both flctl_sel (the control line select), as well as the
	// flash_sel (the memory line select).  Hence we have one fewer ack
	// line.
	wire	io_ack, oled_ack,
			rtc_ack, sdcard_ack, 
			netp_ack, gps_ack, mio_ack, cfg_ack, netb_ack,
			mem_ack, flash_ack, ram_ack;
	reg	many_ack, slow_many_ack;
	reg	slow_ack, scop_ack;
	wire	[5:0]	ack_list;
	assign	ack_list = { ram_ack, flash_ack, mem_ack, netb_ack, netp_ack, slow_ack };
	initial	many_ack = 1'b0;
	always @(posedge i_clk)
		many_ack <= ((ack_list != 6'h20)
			&&(ack_list != 6'h10)
			&&(ack_list != 6'h8)
			&&(ack_list != 6'h4)
			&&(ack_list != 6'h2)
			&&(ack_list != 6'h1)
			&&(ack_list != 6'h0));
	/*
	assign	many_ack = ( 	{ 2'h0, ram_ack}
				+{2'h0, flash_ack }
				+{2'h0, mem_ack }
				+{2'h0, netb_ack }
				+{2'h0, slow_ack } > 3'h1 );
	*/
 
	wire	[7:0] slow_ack_list;
	assign slow_ack_list = { cfg_ack, mio_ack, gps_ack,
			sdcard_ack, rtc_ack, scop_ack, oled_ack, io_ack };
	initial	slow_many_ack = 1'b0;
	always @(posedge i_clk)
		slow_many_ack <= ((slow_ack_list != 8'h80)
			&&(slow_ack_list != 8'h40)
			&&(slow_ack_list != 8'h20)
			&&(slow_ack_list != 8'h10)
			&&(slow_ack_list != 8'h08)
			&&(slow_ack_list != 8'h04)
			&&(slow_ack_list != 8'h02)
			&&(slow_ack_list != 8'h01)
			&&(slow_ack_list != 8'h00));
 
	always @(posedge i_clk)
		wb_ack <= (wb_cyc)&&(|ack_list);
	always @(posedge i_clk)
		slow_ack <= (wb_cyc)&&(|slow_ack_list);
 
	//
	// Peripheral data lines
	//
	wire	[31:0]	io_data, oled_data,
			rtc_data, sdcard_data, 
			netp_data, gps_data, mio_data, cfg_data, netb_data,
			mem_data, flash_data, ram_data;
	reg	[31:0]	slow_data, scop_data;
 
	// 4 control lines, 5x32 data lines ... 
	always @(posedge i_clk)
		if ((ram_ack)||(flash_ack))
			wb_idata <= (ram_ack)?ram_data:flash_data;
		else if ((mem_ack)||(netb_ack))
			wb_idata <= (mem_ack)?mem_data:netb_data;
		else
			wb_idata <= (netp_ack)?netp_data: slow_data;
 
	// 7 control lines, 8x32 data lines
	always @(posedge i_clk)
		if ((cfg_ack)||(mio_ack))
			slow_data <= (cfg_ack) ? cfg_data : mio_data;
		else if ((sdcard_ack)||(rtc_ack))
			slow_data <= (sdcard_ack)?sdcard_data : rtc_data;
		else if ((scop_ack)|(oled_ack))
			slow_data <= (scop_ack)?scop_data:oled_data;
		else
			slow_data <= (gps_ack) ? gps_data : io_data;
 
	//
	// Peripheral stall lines
	//
	// As per the wishbone spec, these cannot be clocked or delayed.  They
	// *must* be done via combinatorial logic.
	//
	wire	io_stall, scop_stall, oled_stall,
			rtc_stall, sdcard_stall, 
			netp_stall, gps_stall, mio_stall, cfg_stall, netb_stall,
			mem_stall, flash_stall, ram_stall,
			many_stall;
	assign	wb_stall = (wb_cyc)&&(
			((io_sel)&&(io_stall))		// Never stalls
			||((scop_sel)&&(scop_stall))	// Never stalls
			||((rtc_sel)&&(rtc_stall))	// Never stalls
			||((sdcard_sel)&&(sdcard_stall))// Never stalls
			||((netp_sel)&&(netp_stall))
			||((gps_sel)&&(gps_stall))	//(maybe? never stalls?)
			||((oled_sel)&&(oled_stall))	// Never stalls
			||((mio_sel)&&(mio_stall))
			||((cfg_sel)&&(cfg_stall))
			||((netb_sel)&&(netb_stall))	// Never stalls
			||((mem_sel)&&(mem_stall))	// Never stalls
			||((flash_sel|flctl_sel)&&(flash_stall))
			||((ram_sel)&&(ram_stall)));
 
 
	//
	// Bus Error calculation(s)
	//
 
	// Selecting nothing is only an error if the strobe line is high as well
	// as the cycle line.  However, this is captured within the wb_err
	// logic itself, so we can ignore it for a line or two.
	assign	none_sel = ( //(skiperr)||
				(~|{ io_sel, scop_sel, flctl_sel, rtc_sel,
					sdcard_sel, netp_sel, gps_sel,
					oled_sel,
					mio_sel, cfg_sel, netb_sel, mem_sel,
					flash_sel,ram_sel }));
	//
	// Selecting multiple devices at once is a design flaw that should
	// never happen.  Hence, if this logic won't build, we won't include
	// it.  Still, having this logic in place has saved my tush more than
	// once.
	//
	reg	[31:0]	sel_addr;
	always @(posedge i_clk)
		sel_addr <= wb_addr;
 
	reg	many_sel_a, many_sel_b, single_sel_a, single_sel_b, last_stb;
	always @(posedge i_clk)
	begin
		last_stb <= wb_stb;
 
		single_sel_a <= (wb_stb)&&((ram_sel)|(flash_sel)
					|(mem_sel)|(netb_sel)|(cfg_sel));
		many_sel_a <= 1'b0;
		if ((ram_sel)&&((flash_sel)||(mem_sel)||(netb_sel)||cfg_sel))
			many_sel_a <= 1'b1;
		else if ((flash_sel)&&((mem_sel)||(netb_sel)||cfg_sel))
			many_sel_a <= 1'b1;
		else if ((mem_sel)&&((netb_sel)||cfg_sel))
			many_sel_a <= 1'b1;
		else if ((netb_sel)&&(cfg_sel))
			many_sel_a <= 1'b1;
 
		single_sel_b <= (wb_stb)&&((mio_sel)||(gps_sel)||(netp_sel)
					||(sdcard_sel)||(rtc_sel)||(flctl_sel)
					||(oled_sel)||(scop_sel)||(io_sel));
		many_sel_b <= 1'b0;
		if ((mio_sel)&&((gps_sel)||(netp_sel)||(sdcard_sel)||(rtc_sel)
				||(flctl_sel)||(scop_sel)||(oled_sel)||(io_sel)))
			many_sel_b <= 1'b1;
		else if ((gps_sel)&&((netp_sel)||(sdcard_sel)||(rtc_sel)
				||(flctl_sel)||(scop_sel)||(oled_sel)||(io_sel)))
			many_sel_b <= 1'b1;
		else if ((netp_sel)&&((sdcard_sel)||(rtc_sel)
				||(flctl_sel)||(scop_sel)||(oled_sel)||(io_sel)))
			many_sel_b <= 1'b1;
		else if ((sdcard_sel)&&((rtc_sel)
				||(flctl_sel)||(scop_sel)||(oled_sel)||(io_sel)))
			many_sel_b <= 1'b1;
		else if ((rtc_sel)&&((flctl_sel)||(scop_sel)||(oled_sel)||(io_sel)))
			many_sel_b <= 1'b1;
		else if ((flctl_sel)&&((scop_sel)||(oled_sel)||(io_sel)))
			many_sel_b <= 1'b1;
		else if ((scop_sel)&&((oled_sel)||(io_sel)))
			many_sel_b <= 1'b1;
		else if ((oled_sel)&&(io_sel))
			many_sel_b <= 1'b1;
	end
 
	wire	sel_err; // 5 inputs
	assign	sel_err = ( (last_stb)&&(~single_sel_a)&&(~single_sel_b))
				||((single_sel_a)&&(single_sel_b))
				||((single_sel_a)&&(many_sel_a))
				||((single_sel_b)&&(many_sel_b));
	assign	wb_err = (wb_cyc)&&(sel_err || many_ack || slow_many_ack||ram_err);
 
 
	// Finally, if we ever encounter a bus error, knowing the address of
	// the error will be important to figuring out how to fix it.  Hence,
	// we grab it here.  Be aware, however, that this might not truly be
	// the address that caused an error: in the case of none_sel it will
	// be, but if many_ack or slow_many_ack are true then we might just be
	// looking at an address on the bus that was nearby the one requested.
	reg	[31:0]	bus_err_addr;
	initial	bus_err_addr = 32'h00;
	always @(posedge i_clk)
		if (wb_err)
			bus_err_addr <= sel_addr;
 
	//
	// I/O peripheral
	//
	// The I/O processor, herein called an fastio.  This is a unique
	// set of peripherals--these are all of the peripherals that can answer
	// in a single clock--or, rather, they are the peripherals that can 
	// answer the bus before their clock.  Hence, the fastio simply consists
	// of a mux that selects between various peripheral responses.  Further,
	// these peripherals are not allowed to stall the bus.
	//
	// There is no option for turning these off--they will always be on.
	wire	[8:0]	master_ints;
	assign	master_ints = { zip_cpu_int, oled_int, rtc_int, sdcard_int,
			enet_tx_int, enet_rx_int,
			scop_int, flash_int, rtc_pps };
	wire	[5:0]	board_ints;
	wire	[3:0]	w_led;
	wire	rtc_ppd;
	fastio	#(
		.AUXUART_SETUP(30'd1736),	// 115200 Baud, 8N1
		.GPSUART_SETUP(30'd20833)	//   9600 Baud, 8N1
		) runio(i_clk, i_sw, i_btn, 
			w_led, o_clr_led0, o_clr_led1, o_clr_led2, o_clr_led3,
			i_aux_rx, o_aux_tx, o_aux_cts, i_gps_rx, o_gps_tx,
			wb_cyc, (io_sel)&&(wb_stb), wb_we, wb_addr[4:0],
				wb_data, io_ack, io_stall, io_data,
			rtc_ppd,
			bus_err_addr, master_ints, w_interrupt,
			board_ints);
	assign	{ gpio_int, auxrx_int, auxtx_int, gpsrx_int, sw_int, btn_int } = board_ints;
 
	/*
	reg	[25:0]	dbg_counter_err, dbg_counter_cyc, dbg_counter_sel,
			dbg_counter_many;
	// assign wb_err = (wb_cyc)&&(sel_err || many_ack || slow_many_ack);
	always @(posedge i_clk)
		if (wbu_cyc)
			dbg_counter_cyc <= 0;
		else if (!dbg_counter_cyc[25])
			dbg_counter_cyc <= dbg_counter_cyc+26'h1;
	always @(posedge i_clk)
		if (wbu_err)
			dbg_counter_err <= 0;
		else if (!dbg_counter_err[25])
			dbg_counter_err <= dbg_counter_err+26'h1;
	always @(posedge i_clk)
		if ((wb_cyc)&&(sel_err))
			dbg_counter_sel <= 0;
		else if (!dbg_counter_sel[25])
			dbg_counter_sel <= dbg_counter_sel+26'h1;
	always @(posedge i_clk)
		if ((wb_cyc)&&(many_ack))
			dbg_counter_many <= 0;
		else if (!dbg_counter_many[25])
			dbg_counter_many <= dbg_counter_many+26'h1;
	assign o_led = {
		(!dbg_counter_many[25])|w_led[3],
		(!dbg_counter_sel[25])|w_led[2],
		(!dbg_counter_cyc[25])|w_led[1],
		(!dbg_counter_err[25])|w_led[0] };
	*/
	assign	o_led = w_led;
 
 
	//
	//
	//	Real Time Clock (RTC) device level access
	//
	//
	wire	gps_tracking, ck_pps;
	wire	[63:0]	gps_step;
`ifdef	RTC_ACCESS
	rtcgps
		// #(32'h15798f)	// 2^48 / 200MHz
		#(32'h1a6e3a)	// 2^48 / 162.5 MHz
		thertc(i_clk,
			wb_cyc, (wb_stb)&&(rtc_sel), wb_we,
				wb_addr[1:0], wb_data,
				rtc_data, rtc_int, rtc_ppd,
			gps_tracking, ck_pps, gps_step[47:16], rtc_pps);
`else
	assign	rtc_data = 32'h00;
	assign	rtc_int   = 1'b0;
	assign	rtc_pps   = 1'b0;
	assign	rtc_ppd   = 1'b0;
`endif
	reg	r_rtc_ack;
	initial	r_rtc_ack = 1'b0;
	always @(posedge i_clk)
		r_rtc_ack <= (wb_stb)&&(rtc_sel);
	assign	rtc_ack = r_rtc_ack;
	assign	rtc_stall = 1'b0;
 
	//
	//
	//	SDCard device level access
	//
	//
`ifdef	SDCARD_ACCESS
	wire	[31:0]	sd_dbg;
	// SPI mapping
	wire	w_sd_cs_n, w_sd_mosi, w_sd_miso;
 
	sdspi	sdctrl(i_clk,
			wb_cyc, (wb_stb)&&(sdcard_sel), wb_we,
				wb_addr[1:0], wb_data,
				sdcard_ack, sdcard_stall, sdcard_data,
			w_sd_cs_n, o_sd_sck, w_sd_mosi, w_sd_miso, 
			sdcard_int, 1'b1, sd_dbg);
	assign	w_sd_miso = i_sd_data[0];
	assign	o_sd_data = { w_sd_cs_n, 3'b111 };
	assign	o_sd_cmd  = w_sd_mosi;
`else
	reg	r_sdcard_ack;
	always @(posedge i_clk)
		r_sdcard_ack <= (wb_stb)&&(sdcard_sel);
	assign	sdcard_ack = r_sdcard_ack;
 
	assign	sdcard_data = 32'h00;
	assign	sdcard_stall= 1'b0;
	assign	sdcard_int  = 1'b0;
`endif
 
	//
	//
	//	OLEDrgb device control
	//
	//
`ifdef	OLEDRGB_ACCESS
	wboled
		.#( .CBITS(5))// Div ck by 2^5=32, words take 200ns@162.5MHz
		rgbctrl(i_clk,
			wb_cyc, (wb_stb)&&(oled_sel), wb_we,
				wb_addr[1:0], wb_data,
				oled_ack, oled_stall, oled_data,
			o_oled_sck, o_oled_cs_n, o_oled_mosi, o_oled_dcn,
			{ o_oled_reset_n, o_oled_vccen, o_oled_pmoden },
			oled_int);
`else
	assign	o_oled_cs_n    = 1'b1;
	assign	o_oled_sck     = 1'b1;
	assign	o_oled_mosi    = 1'b1;
	assign	o_oled_dcn     = 1'b1;
	assign	o_oled_reset_n = 1'b0;
	assign	o_oled_vccen   = 1'b0;
	assign	o_oled_pmoden  = 1'b0;
 
	reg	r_oled_ack;
	always @(posedge i_clk)
		r_oled_ack <= (wb_stb)&&(oled_sel);
	assign	oled_ack = r_oled_ack;
 
	assign	oled_data = 32'h00;
	assign	oled_stall= 1'b0;
	assign	oled_int  = 1'b0;
`endif
 
	//
	//
	//	GPS CLOCK CONTROLS, BOTH THE TEST BENCH AND THE CLOCK ITSELF
	//
	//
	wire	[63:0]	gps_now, gps_err;
	wire	[31:0]	gck_data, gtb_data;
	wire	gck_ack, gck_stall, gtb_ack, gtb_stall;
`ifdef	GPS_CLOCK
	//
	//	GPS CLOCK SCHOOL TESTING
	//
	wire	gps_pps, tb_pps, gps_locked;
	wire	[1:0]	gps_dbg_tick;
 
	gpsclock_tb ppscktb(i_clk, ck_pps, tb_pps,
			(wb_stb)&&(gps_sel)&&(wb_addr[3]),
				wb_we, wb_addr[2:0],
				wb_data, gtb_ack, gtb_stall, gtb_data,
			gps_err, gps_now, gps_step);
`ifdef	GPSTB
	assign	gps_pps = tb_pps; // Let the truth come from our test bench
`else
	assign	gps_pps = i_gps_pps;
`endif
	wire	gps_led;
 
	//
	//	GPS CLOCK CONTROL
	//
	gpsclock #(
		.DEFAULT_STEP(32'h81a6e39b) // 162.5 MHz
		) ppsck(i_clk, 1'b0, gps_pps, ck_pps, gps_led,
			(wb_stb)&&(gps_sel)&&(~wb_addr[3]),
				wb_we, wb_addr[1:0],
				wb_data, gck_ack, gck_stall, gck_data,
			gps_tracking, gps_now, gps_step, gps_err, gps_locked,
			gps_dbg_tick);
`else
 
	assign	gps_err = 64'h0;
	assign	gps_now = 64'h0;
	assign	gck_data = 32'h0;
	assign	gtb_data = 32'h0;
	assign	gtb_stall = 1'b0;
	assign	gck_stall = 1'b0;
	assign	ck_pps = 1'b0;
 
	assign	gps_tracking = 1'b0;
	// Appropriate step for a 200MHz clock
	assign	gps_step = { 16'h00, 32'h015798e, 16'h00 };
 
	reg	r_gck_ack;
	always @(posedge i_clk)
		r_gck_ack <= (wb_stb)&&(gps_sel);
	assign	gck_ack = r_gck_ack;
	assign	gtb_ack = r_gck_ack;
 
`endif
 
	assign	gps_ack   = (gck_ack | gtb_ack);
	assign	gps_stall = (gck_stall | gtb_stall);
	assign	gps_data  = (gck_ack) ? gck_data : gtb_data;
 
 
	//
	//	ETHERNET DEVICE ACCESS
	//
`ifdef	ETHERNET_ACCESS
	reg	r_mio_ack, r_netb_ack, r_netp_ack;
	always @(posedge i_clk)
		r_mio_ack <= (wb_stb)&&(mio_sel);
	always @(posedge i_clk)
		r_netp_ack <= (wb_stb)&&(netp_sel);
	assign	mio_ack = r_mio_ack;
	assign	netp_ack = r_netp_ack;
 
	assign	mio_data  = 32'h00;
	assign	netp_data = 32'h00;
	assign	mio_stall = 1'b0;
	assign	netp_stall= 1'b0;
	assign	enet_rx_int = 1'b0;
	assign	enet_tx_int = 1'b0;
 
	enetctrl #(3)
		mdio(i_clk, i_rst, wb_cyc, (wb_stb)&&(netb_sel), wb_we,
			wb_addr[4:0], wb_data[15:0],
			netb_ack, netb_stall, netb_data,
			o_mdclk, o_mdio, i_mdio, o_mdwe);
`else
	reg	r_mio_ack, r_netb_ack, r_netp_ack;
	always @(posedge i_clk)
		r_mio_ack <= (wb_stb)&&(mio_sel);
	always @(posedge i_clk)
		r_netp_ack <= (wb_stb)&&(netp_sel);
	assign	mio_ack = r_mio_ack;
	assign	netp_ack = r_netp_ack;
 
	assign	mio_data  = 32'h00;
	assign	netp_data = 32'h00;
	assign	mio_stall = 1'b0;
	assign	netp_stall= 1'b0;
	assign	enet_rx_int = 1'b0;
	assign	enet_tx_int = 1'b0;
 
	//
	// 2kW memory, 1kW for each of transmit and receive.  (Max pkt length
	// is 512W, so this allows for two 512W in memory.)  Since we don't
	// really have ethernet without ETHERNET_ACCESS defined, this just
	// consumes resources for us so we have an idea of what might be 
	// available when we do have ETHERNET_ACCESS defined.
	//
	memdev #(11) enet_buffers(i_clk, wb_cyc, (wb_stb)&&(netb_sel), wb_we,
		wb_addr[10:0], wb_data, netb_ack, netb_stall, netb_data);
	assign	o_mdclk = 1'b1;
	assign	o_mdio = 1'b1;
	assign	o_mdwe = 1'b1;
 
`endif
 
 
	//
	//	MULTIBOOT/ICAPE2 CONFIGURATION ACCESS
	//
`ifdef	ICAPE_ACCESS
	wire	[31:0]	cfg_debug;
	wbicapetwo	fpga_cfg(i_clk, wb_cyc,(cfg_sel)&&(wb_stb), wb_we,
				wb_addr[4:0], wb_data,
				cfg_ack, cfg_stall, cfg_data, cfg_debug);
`else
	reg	r_cfg_ack;
	always @(posedge i_clk)
		r_cfg_ack <= (cfg_sel)&&(wb_stb);
	assign	cfg_ack   = r_cfg_ack;
	assign	cfg_stall = 1'b0;
	assign	cfg_data  = 32'h00;
`endif
 
	//
	//	RAM MEMORY ACCESS
	//
	// There is no option to turn this off--this RAM must always be
	// present in the design.
	memdev	#(.AW(15),
		.EXTRACLOCK(1)) // 32kW, or 128kB, 15 address lines
		blkram(i_clk, wb_cyc, (wb_stb)&&(mem_sel), wb_we, wb_addr[14:0],
				wb_data, mem_ack, mem_stall, mem_data);
 
	//
	//	FLASH MEMORY ACCESS
	//
`ifdef	FLASH_ACCESS
`ifdef	FLASH_SCOPE
	wire	[31:0]	flash_debug;
`endif
	wire	w_ignore_cmd_accepted;
	eqspiflash	flashmem(i_clk, i_rst,
		wb_cyc,(wb_stb)&&(flash_sel),(wb_stb)&&(flctl_sel),wb_we,
			wb_addr[21:0], wb_data,
		flash_ack, flash_stall, flash_data,
		o_qspi_sck, o_qspi_cs_n, o_qspi_mod, o_qspi_dat, i_qspi_dat,
		flash_int, w_ignore_cmd_accepted
`ifdef	FLASH_SCOPE
		, flash_debug
`endif
		);
`else
	assign	o_qspi_sck = 1'b1;
	assign	o_qspi_cs_n= 1'b1;
	assign	o_qspi_mod = 2'b01;
	assign	o_qspi_dat = 4'h0;
	assign	flash_data = 32'h00;
	assign	flash_stall  = 1'b0;
	assign	flash_int = 1'b0;
 
	reg	r_flash_ack;
	always @(posedge i_clk)
		r_flash_ack <= (wb_stb)&&(flash_sel);
	assign	flash_ack = r_flash_ack;
`endif
 
 
	//
	//
	//	DDR3-SDRAM
	//
	//
`ifdef	SDRAM_ACCESS
	wire	[63:0]	w_ram_wide_data;
	wbddrsdram	#(13,13'd1520) rami(i_clk, i_rst,
		wb_cyc, (wb_stb)&&(ram_sel), wb_we, wb_addr[24:0],
			{ wb_data, wb_data }, (wb_addr[25])? 8'hf0:8'h0f,
			ram_ack, ram_stall, w_ram_wide_data,
		o_ddr_reset_n, o_ddr_cke, o_ddr_bus_oe,
		o_ddr_cmd_a, o_ddr_cmd_b, o_ddr_data, i_ddr_data);
 
	// assign	ram_data = (wb_addr[25])?w_ram_wide_data[63:32]:w_ram_wide_data[
	assign	ram_data = w_ram_wide_data[31:0];
`else
	assign	ram_data  = 32'h00;
	assign	ram_stall = 1'b0;
	reg	r_ram_ack;
	always @(posedge i_clk)
		r_ram_ack <= (wb_stb)&&(ram_sel);
	assign	ram_ack = r_ram_ack;
 
	// And idle the DDR3 SDRAM
	assign	o_ddr_reset_n = 1'b0;	// Leave the SDRAM in reset
	assign	o_ddr_cke     = 1'b0;	// Disable the SDRAM clock
	// DQS
	assign	o_ddr_dqs = 1'b0; // Leave DQS pins in high impedence
	// DDR3 control wires (not enabled if CKE=0)
	assign	o_ddr_cs_n	= 1'b1;	 // Deselect command
	assign	o_ddr_ras_n	= 1'b1;
	assign	o_ddr_cas_n	= 1'b1;
	assign	o_ddr_we_n	= 1'b1;
	// (Unused) data wires
	assign	o_ddr_addr = 14'h00;
	assign	o_ddr_ba   = 3'h0;
	assign	o_ddr_data = 32'h00;
`endif
 
 
	//
	//
	//	WISHBONE SCOPES
	//
	//
	//
	//
	wire	[31:0]	scop_a_data;
	wire	scop_a_ack, scop_a_stall, scop_a_interrupt;
`ifdef	CPU_SCOPE
	wire	[31:0]	scop_cpu_data;
	wire	scop_cpu_ack, scop_cpu_stall, scop_cpu_interrupt;
	wire	scop_cpu_trigger;
	// assign	scop_cpu_trigger = zip_scope_data[30];
	assign	scop_cpu_trigger = (wb_stb)&&(mem_sel)&&(~wb_we)
			&&(wb_err)||(zip_scope_data[31]);
	wbscope #(5'd13) cpuscope(i_clk, 1'b1,(scop_cpu_trigger), zip_scope_data,
		// Wishbone interface
		i_clk, wb_cyc, ((wb_stb)&&(scop_sel)&&(wb_addr[2:1]==2'b00)),
			wb_we, wb_addr[0], wb_data,
			scop_cpu_ack, scop_cpu_stall, scop_cpu_data,
		scop_cpu_interrupt);
 
	assign	scop_a_data = scop_cpu_data;
	assign	scop_a_ack = scop_cpu_ack;
	assign	scop_a_stall = scop_cpu_stall;
	assign	scop_a_interrupt = scop_cpu_interrupt;
`else
`ifdef	FLASH_SCOPE
	wire	[31:0]	scop_flash_data;
	wire	scop_flash_ack, scop_flash_stall, scop_flash_interrupt;
	wire	scop_flash_trigger;
	// assign	scop_cpu_trigger = zip_scope_data[30];
	assign	scop_flash_trigger = (wb_stb)&&((flash_sel)||(flctl_sel));
	wbscope #(5'd13) flashscope(i_clk, 1'b1,
			(scop_flash_trigger), flash_debug,
		// Wishbone interface
		i_clk, wb_cyc, ((wb_stb)&&(scop_sel)&&(wb_addr[2:1]==2'b00)),
			wb_we, wb_addr[0], wb_data,
			scop_flash_ack, scop_flash_stall, scop_flash_data,
		scop_flash_interrupt);
 
	assign	scop_a_data = scop_flash_data;
	assign	scop_a_ack = scop_flash_ack;
	assign	scop_a_stall = scop_flash_stall;
	assign	scop_a_interrupt = scop_flash_interrupt;
`else
	reg	r_scop_a_ack;
	always @(posedge i_clk)
		r_scop_a_ack <= (wb_stb)&&(scop_sel)&&(wb_addr[2:1] == 2'b00);
	assign	scop_a_data = 32'h00;
	assign	scop_a_ack = r_scop_a_ack;
	assign	scop_a_stall = 1'b0;
	assign	scop_a_interrupt = 1'b0;
`endif
`endif
 
	wire	[31:0]	scop_b_data;
	wire	scop_b_ack, scop_b_stall, scop_b_interrupt;
`ifdef	GPS_SCOPE
	reg	[18:0]	r_gps_debug;
	wire	[31:0]	scop_gps_data;
	wire		scop_gps_ack, scop_gps_stall, scop_gps_interrupt;
	always @(posedge i_clk)
		r_gps_debug <= {
			gps_dbg_tick, gps_tracking, gps_locked,
				gpu_data[7:0],
			// (wb_cyc)&&(wb_stb)&&(io_sel),
			(wb_stb)&&(io_sel)&&(wb_addr[4:3]==2'b11)&&(wb_we),
			(wb_stb)&&(gps_sel)&&(wb_addr[3:2]==2'b01),
				gpu_int,
				i_gps_rx, rtc_pps, ck_pps, i_gps_pps };
	wbscopc	#(5'd13,19,32,1) gpsscope(i_clk, 1'b1, ck_pps, r_gps_debug,
		// Wishbone interface
		i_clk, wb_cyc, ((wb_stb)&&(scop_sel)&&(wb_addr[2:1]==2'b01)),
			wb_we, wb_addr[0], wb_data,
			scop_gps_ack, scop_gps_stall, scop_gps_data,
		scop_gps_interrupt);
 
	assign	scop_b_ack   = scop_gps_ack;
	assign	scop_b_stall = scop_gps_stall;
	assign	scop_b_data  = scop_gps_data;
	assign	scop_b_interrupt = scop_gps_interrupt;
`else
`ifdef	CFG_SCOPE
	wire	[31:0]	scop_cfg_data;
	wire		scop_cfg_ack, scop_cfg_stall, scop_cfg_interrupt;
	wire	[31:0]	cfg_debug_2;
	assign	cfg_debug_2 = {
			wb_ack, cfg_debug[30:17], slow_ack,
				slow_data[7:0], wb_data[7:0]
			};
	wbscope	#(5'd8,32,1) cfgscope(i_clk, 1'b1, (cfg_sel)&&(wb_stb),
			cfg_debug_2,
		// Wishbone interface
		i_clk, wb_cyc, ((wb_stb)&&(scop_sel)&&(wb_addr[2:1]==2'b01)),
			wb_we, wb_addr[0], wb_data,
			scop_cfg_ack, scop_cfg_stall, scop_cfg_data,
		scop_cfg_interrupt);
 
	assign	scop_b_data = scop_cfg_data;
	assign	scop_b_stall = scop_cfg_stall;
	assign	scop_b_ack = scop_cfg_ack;
	assign	scop_b_interrupt = scop_cfg_interrupt;
`else
	assign	scop_b_data = 32'h00;
	assign	scop_b_stall = 1'b0;
	assign	scop_b_interrupt = 1'b0;
 
	reg	r_scop_b_ack;
	always @(posedge i_clk)
		r_scop_b_ack <= (wb_stb)&&(scop_sel)&&(wb_addr[2:1] == 2'b01);
	assign	scop_b_ack  = r_scop_b_ack;
`endif
`endif
 
	//
	// SCOPE C
	//
	wire	[31:0]	scop_c_data;
	wire	scop_c_ack, scop_c_stall, scop_c_interrupt;
	//
`ifdef	SDRAM_SCOPE
	wire	[31:0]	scop_sdram_data;
	wire		scop_sdram_ack, scop_sdram_stall, scop_sdram_interrupt;
	wire		sdram_trigger;
	wire	[31:0]	sdram_debug;
	assign	sdram_trigger = (ram_sel)&&(wb_stb);
	assign	sdram_debug= { 
			o_ddr_ras_n, o_ddr_cas_n, o_ddr_we_n,
			(wb_stb)&&(ram_sel), wb_we, ram_stall, ram_ack,
			o_ddr_dqs, o_ddr_dm, o_ddr_bus_oe,
				o_ddr_addr[10], o_ddr_addr[3],
			o_ddr_data[5:0], i_ddr_data[5:0], 8'h00
		};
 
	wbscope	#(5'd12,32,1) ramscope(i_clk, 1'b1, sdram_trigger, sdram_debug,
		// Wishbone interface
		i_clk, wb_cyc, ((wb_stb)&&(scop_sel)&&(wb_addr[2:1]==2'b10)),
			wb_we, wb_addr[0], wb_data,
			scop_sdram_ack, scop_sdram_stall, scop_sdram_data,
		scop_sdram_interrupt);
 
	assign	scop_c_ack       = scop_sdram_ack;
	assign	scop_c_stall     = scop_sdram_stall;
	assign	scop_c_data      = scop_sdram_data;
	assign	scop_c_interrupt = scop_sdram_interrupt;
`else
	assign	scop_c_data = 32'h00;
	assign	scop_c_stall = 1'b0;
	assign	scop_c_interrupt = 1'b0;
 
	reg	r_scop_c_ack;
	always @(posedge i_clk)
		r_scop_c_ack <= (wb_stb)&&(scop_sel)&&(wb_addr[2:1] == 2'b10);
	assign	scop_c_ack = r_scop_c_ack;
`endif
 
	//
	// SCOPE D
	//
	wire	[31:0]	scop_d_data;
	wire	scop_d_ack, scop_d_stall, scop_d_interrupt;
	//
//`else
	assign	scop_d_data = 32'h00;
	assign	scop_d_stall = 1'b0;
	assign	scop_d_interrupt = 1'b0;
 
	reg	r_scop_d_ack;
	always @(posedge i_clk)
		r_scop_d_ack <= (wb_stb)&&(scop_sel)&&(wb_addr[2:1] == 2'b11);
	assign	scop_d_ack = r_scop_d_ack;
//`endif
 
	reg	all_scope_interrupts;
	always @(posedge i_clk)
		all_scope_interrupts <= (scop_a_interrupt)
				|| (scop_b_interrupt)
				|| (scop_c_interrupt)
				|| (scop_d_interrupt);
	assign	scop_int = all_scope_interrupts;
 
	// Scopes don't stall, so this line is more formality than anything
	// else.
	assign	scop_stall = ((wb_addr[2:1]==2'b0)?scop_a_stall
				: ((wb_addr[2:1]==2'b01)?scop_b_stall
				: ((wb_addr[2:1]==2'b10)?scop_c_stall
				: scop_d_stall))); // Will always be 1'b0;
	initial	scop_ack = 1'b0;
	always @(posedge i_clk)
		scop_ack  <= scop_a_ack | scop_b_ack | scop_c_ack | scop_d_ack;
	always @(posedge i_clk)
		if (scop_a_ack)
			scop_data <= scop_a_data;
		else if (scop_b_ack)
			scop_data <= scop_b_data;
		else if (scop_c_ack)
			scop_data <= scop_c_data;
		else // if (scop_d_ack)
			scop_data <= scop_d_data;
 
endmodule