////////////////////////////////////////////////////////////////////// //// //// //// File name "pciw_pcir_fifos.v" //// //// //// //// This file is part of the "PCI bridge" project //// //// http://www.opencores.org/cores/pci/ //// //// //// //// Author(s): //// //// - Miha Dolenc (mihad@opencores.org) //// //// //// //// All additional information is avaliable in the README //// //// file. //// //// //// //// //// ////////////////////////////////////////////////////////////////////// //// //// //// Copyright (C) 2000 Miha Dolenc, mihad@opencores.org //// //// //// //// This source file may be used and distributed without //// //// restriction provided that this copyright statement is not //// //// removed from the file and that any derivative work contains //// //// the original copyright notice and the associated disclaimer. //// //// //// //// This source file is free software; you can redistribute it //// //// and/or modify it under the terms of the GNU Lesser General //// //// Public License as published by the Free Software Foundation; //// //// either version 2.1 of the License, or (at your option) any //// //// later version. //// //// //// //// This source is distributed in the hope that it will be //// //// useful, but WITHOUT ANY WARRANTY; without even the implied //// //// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR //// //// PURPOSE. See the GNU Lesser General Public License for more //// //// details. //// //// //// //// You should have received a copy of the GNU Lesser General //// //// Public License along with this source; if not, download it //// //// from http://www.opencores.org/lgpl.shtml //// //// //// ////////////////////////////////////////////////////////////////////// // // CVS Revision History // // $Log: pci_pciw_pcir_fifos.v,v $ // Revision 1.1 2007-03-20 17:50:56 sithglan // add shit // // Revision 1.6 2003/10/17 09:11:52 markom // mbist signals updated according to newest convention // // Revision 1.5 2003/08/14 13:06:03 simons // synchronizer_flop replaced with pci_synchronizer_flop, artisan ram instance updated. // // Revision 1.4 2003/08/08 16:36:33 tadejm // Added 'three_left_out' to pci_pciw_fifo signaling three locations before full. Added comparison between current registered cbe and next unregistered cbe to signal wb_master whether it is allowed to performe burst or not. Due to this, I needed 'three_left_out' so that writing to pci_pciw_fifo can be registered, otherwise timing problems would occure. // // Revision 1.3 2003/03/26 13:16:18 mihad // Added the reset value parameter to the synchronizer flop module. // Added resets to all synchronizer flop instances. // Repaired initial sync value in fifos. // // Revision 1.2 2003/01/30 22:01:08 mihad // Updated synchronization in top level fifo modules. // // Revision 1.1 2003/01/27 16:49:31 mihad // Changed module and file names. Updated scripts accordingly. FIFO synchronizations changed. // // Revision 1.10 2002/10/18 03:36:37 tadejm // Changed wrong signal name mbist_sen into mbist_ctrl_i. // // Revision 1.9 2002/10/17 22:51:08 tadejm // Changed BIST signals for RAMs. // // Revision 1.8 2002/10/11 10:09:01 mihad // Added additional testcase and changed rst name in BIST to trst // // Revision 1.7 2002/10/08 17:17:06 mihad // Added BIST signals for RAMs. // // Revision 1.6 2002/09/30 16:03:04 mihad // Added meta flop module for easier meta stable FF identification during synthesis // // Revision 1.5 2002/09/25 15:53:52 mihad // Removed all logic from asynchronous reset network // // Revision 1.4 2002/03/05 11:53:47 mihad // Added some testcases, removed un-needed fifo signals // // Revision 1.3 2002/02/01 15:25:13 mihad // Repaired a few bugs, updated specification, added test bench files and design document // // Revision 1.2 2001/10/05 08:14:30 mihad // Updated all files with inclusion of timescale file for simulation purposes. // // Revision 1.1.1.1 2001/10/02 15:33:47 mihad // New project directory structure // // `include "pci_constants.v" // synopsys translate_off `include "timescale.v" // synopsys translate_on module pci_pciw_pcir_fifos ( wb_clock_in, pci_clock_in, reset_in, pciw_wenable_in, pciw_addr_data_in, pciw_cbe_in, pciw_control_in, pciw_renable_in, pciw_addr_data_out, pciw_cbe_out, pciw_control_out, // pciw_flush_in, // not used pciw_three_left_out, pciw_two_left_out, pciw_almost_full_out, pciw_full_out, pciw_almost_empty_out, pciw_empty_out, pciw_transaction_ready_out, pcir_wenable_in, pcir_data_in, pcir_be_in, pcir_control_in, pcir_renable_in, pcir_data_out, pcir_be_out, pcir_control_out, pcir_flush_in, pcir_full_out, pcir_almost_empty_out, pcir_empty_out, pcir_transaction_ready_out `ifdef PCI_BIST , // debug chain signals mbist_si_i, // bist scan serial in mbist_so_o, // bist scan serial out mbist_ctrl_i // bist chain shift control `endif ) ; /*----------------------------------------------------------------------------------------------------------- System inputs: wb_clock_in - WISHBONE bus clock pci_clock_in - PCI bus clock reset_in - reset from control logic -------------------------------------------------------------------------------------------------------------*/ input wb_clock_in, pci_clock_in, reset_in ; /*----------------------------------------------------------------------------------------------------------- PCI WRITE FIFO interface signals prefixed with pciw_ - FIFO is used for posted writes initiated by external PCI master through PCI target interface, traveling through FIFO and are completed on WISHBONE by WISHBONE master interface write enable signal: pciw_wenable_in = write enable input for PCIW_FIFO - driven by PCI TARGET interface data input signals: pciw_addr_data_in = data input - data from PCI bus - first entry of transaction is address others are data entries pciw_cbe_in = bus command/byte enable(~#BE[3:0]) input - first entry of transaction is bus command, other are byte enables pciw_control_in = control input - encoded control bus input read enable signal: pciw_renable_in = read enable input driven by WISHBONE master interface data output signals: pciw_addr_data_out = data output - data from PCI bus - first entry of transaction is address, others are data entries pciw_cbe_out = bus command/byte enable output - first entry of transaction is bus command, others are byte enables pciw_control_out = control input - encoded control bus input status signals - monitored by various resources in the core pciw_flush_in = flush signal input for PCIW_FIFO - when asserted, fifo is flushed(emptied) pciw_almost_full_out = almost full output from PCIW_FIFO pciw_full_out = full output from PCIW_FIFO pciw_almost_empty_out = almost empty output from PCIW_FIFO pciw_empty_out = empty output from PCIW_FIFO pciw_transaction_ready_out = output indicating that one complete transaction is waiting in PCIW_FIFO -----------------------------------------------------------------------------------------------------------*/ // input control and data input pciw_wenable_in ; input [31:0] pciw_addr_data_in ; input [3:0] pciw_cbe_in ; input [3:0] pciw_control_in ; // output control and data input pciw_renable_in ; output [31:0] pciw_addr_data_out ; output [3:0] pciw_cbe_out ; output [3:0] pciw_control_out ; // flush input //input pciw_flush_in ; // not used // status outputs output pciw_three_left_out ; output pciw_two_left_out ; output pciw_almost_full_out ; output pciw_full_out ; output pciw_almost_empty_out ; output pciw_empty_out ; output pciw_transaction_ready_out ; /*----------------------------------------------------------------------------------------------------------- PCI READ FIFO interface signals prefixed with pcir_ - FIFO is used for holding delayed read completions initiated by master on PCI bus and completed on WISHBONE bus, write enable signal: pcir_wenable_in = write enable input for PCIR_FIFO - driven by WISHBONE master interface data input signals: pcir_data_in = data input - data from WISHBONE bus - there is no address entry here, since address is stored in separate register pcir_be_in = byte enable(~SEL[3:0]) input - byte enables - same through one transaction pcir_control_in = control input - encoded control bus input read enable signal: pcir_renable_in = read enable input driven by PCI target interface data output signals: pcir_data_out = data output - data from WISHBONE bus pcir_be_out = byte enable output(~SEL) pcir_control_out = control output - encoded control bus output status signals - monitored by various resources in the core pcir_flush_in = flush signal input for PCIR_FIFO - when asserted, fifo is flushed(emptied) pcir full_out = full output from PCIR_FIFO pcir_almost_empty_out = almost empty output from PCIR_FIFO pcir_empty_out = empty output from PCIR_FIFO pcir_transaction_ready_out = output indicating that one complete transaction is waiting in PCIR_FIFO -----------------------------------------------------------------------------------------------------------*/ // input control and data input pcir_wenable_in ; input [31:0] pcir_data_in ; input [3:0] pcir_be_in ; input [3:0] pcir_control_in ; // output control and data input pcir_renable_in ; output [31:0] pcir_data_out ; output [3:0] pcir_be_out ; output [3:0] pcir_control_out ; // flush input input pcir_flush_in ; // status outputs output pcir_full_out ; output pcir_almost_empty_out ; output pcir_empty_out ; output pcir_transaction_ready_out ; `ifdef PCI_BIST /*----------------------------------------------------- BIST debug chain port signals -----------------------------------------------------*/ input mbist_si_i; // bist scan serial in output mbist_so_o; // bist scan serial out input [`PCI_MBIST_CTRL_WIDTH - 1:0] mbist_ctrl_i; // bist chain shift control `endif /*----------------------------------------------------------------------------------------------------------- Address length parameters: PCIW_DEPTH = defines PCIW_FIFO depth PCIR_DEPTH = defines PCIR_FIFO depth PCIW_ADDR_LENGTH = defines PCIW_FIFO's location address length - log2(PCIW_DEPTH) PCIR_ADDR_LENGTH = defines PCIR_FIFO's location address length - log2(PCIR_DEPTH) -----------------------------------------------------------------------------------------------------------*/ parameter PCIW_DEPTH = `PCIW_DEPTH ; parameter PCIW_ADDR_LENGTH = `PCIW_ADDR_LENGTH ; parameter PCIR_DEPTH = `PCIR_DEPTH ; parameter PCIR_ADDR_LENGTH = `PCIR_ADDR_LENGTH ; /*----------------------------------------------------------------------------------------------------------- pciw_wallow = PCIW_FIFO write allow wire - writes to FIFO are allowed when FIFO isn't full and write enable is 1 pciw_rallow = PCIW_FIFO read allow wire - reads from FIFO are allowed when FIFO isn't empty and read enable is 1 -----------------------------------------------------------------------------------------------------------*/ wire pciw_wallow ; wire pciw_rallow ; /*----------------------------------------------------------------------------------------------------------- pcir_wallow = PCIR_FIFO write allow wire - writes to FIFO are allowed when FIFO isn't full and write enable is 1 pcir_rallow = PCIR_FIFO read allow wire - reads from FIFO are allowed when FIFO isn't empty and read enable is 1 -----------------------------------------------------------------------------------------------------------*/ wire pcir_wallow ; wire pcir_rallow ; /*----------------------------------------------------------------------------------------------------------- wires for address port conections from PCIW_FIFO control logic to RAM blocks used for PCIW_FIFO -----------------------------------------------------------------------------------------------------------*/ wire [(PCIW_ADDR_LENGTH - 1):0] pciw_raddr ; wire [(PCIW_ADDR_LENGTH - 1):0] pciw_waddr ; /*----------------------------------------------------------------------------------------------------------- wires for address port conections from PCIR_FIFO control logic to RAM blocks used for PCIR_FIFO -----------------------------------------------------------------------------------------------------------*/ wire [(PCIR_ADDR_LENGTH - 1):0] pcir_raddr ; wire [(PCIR_ADDR_LENGTH - 1):0] pcir_waddr ; /*----------------------------------------------------------------------------------------------------------- PCIW_FIFO transaction counters: used to count incoming transactions and outgoing transactions. When number of input transactions is equal to number of output transactions, it means that there isn't any complete transaction currently present in the FIFO. -----------------------------------------------------------------------------------------------------------*/ reg [(PCIW_ADDR_LENGTH - 1):0] pciw_inTransactionCount ; reg [(PCIW_ADDR_LENGTH - 1):0] pciw_outTransactionCount ; /*----------------------------------------------------------------------------------------------------------- FlipFlops for indicating if complete delayed read completion is present in the FIFO -----------------------------------------------------------------------------------------------------------*/ /*reg pcir_inTransactionCount ; reg pcir_outTransactionCount ;*/ /*----------------------------------------------------------------------------------------------------------- wires monitoring control bus. When control bus on a write transaction has a value of `LAST, it means that complete transaction is in the FIFO. When control bus on a read transaction has a value of `LAST, it means that there was one complete transaction taken out of FIFO. -----------------------------------------------------------------------------------------------------------*/ wire pciw_last_in = pciw_control_in[`LAST_CTRL_BIT] ; wire pciw_last_out = pciw_control_out[`LAST_CTRL_BIT] ; /*wire pcir_last_in = pcir_wallow && (pcir_control_in == `LAST) ; wire pcir_last_out = pcir_rallow && (pcir_control_out == `LAST) ;*/ wire pciw_empty ; wire pcir_empty ; assign pciw_empty_out = pciw_empty ; assign pcir_empty_out = pcir_empty ; // clear wires for clearing FFs and registers wire pciw_clear = reset_in /*|| pciw_flush_in*/ ; // PCIW_FIFO's clear signal - flush not used wire pcir_clear = reset_in /*|| pcir_flush_in*/ ; // PCIR_FIFO's clear signal - flush changed to synchronous op. /*----------------------------------------------------------------------------------------------------------- Definitions of wires for connecting RAM instances -----------------------------------------------------------------------------------------------------------*/ wire [39:0] dpram_portA_output ; wire [39:0] dpram_portB_output ; wire [39:0] dpram_portA_input = {pciw_control_in, pciw_cbe_in, pciw_addr_data_in} ; wire [39:0] dpram_portB_input = {pcir_control_in, pcir_be_in, pcir_data_in} ; /*----------------------------------------------------------------------------------------------------------- Fifo output assignments - each ram port provides data for different fifo -----------------------------------------------------------------------------------------------------------*/ assign pciw_control_out = dpram_portB_output[39:36] ; assign pcir_control_out = dpram_portA_output[39:36] ; assign pciw_cbe_out = dpram_portB_output[35:32] ; assign pcir_be_out = dpram_portA_output[35:32] ; assign pciw_addr_data_out = dpram_portB_output[31:0] ; assign pcir_data_out = dpram_portA_output[31:0] ; `ifdef PCI_RAM_DONT_SHARE /*----------------------------------------------------------------------------------------------------------- Piece of code in this ifdef section is used in applications which can provide enough RAM instances to accomodate four fifos - each occupying its own instance of ram. Ports are connected in such a way, that instances of RAMs can be changed from two port to dual port ( async read/write port ). In that case, write port is always port a and read port is port b. -----------------------------------------------------------------------------------------------------------*/ /*----------------------------------------------------------------------------------------------------------- Pad redundant address lines with zeros. This may seem stupid, but it comes in perfect for FPGA impl. -----------------------------------------------------------------------------------------------------------*/ /* wire [(`PCIW_FIFO_RAM_ADDR_LENGTH - PCIW_ADDR_LENGTH - 1):0] pciw_addr_prefix = {( `PCIW_FIFO_RAM_ADDR_LENGTH - PCIW_ADDR_LENGTH){1'b0}} ; wire [(`PCIR_FIFO_RAM_ADDR_LENGTH - PCIR_ADDR_LENGTH - 1):0] pcir_addr_prefix = {( `PCIR_FIFO_RAM_ADDR_LENGTH - PCIR_ADDR_LENGTH){1'b0}} ; */ // compose complete port addresses wire [(`PCI_FIFO_RAM_ADDR_LENGTH-1):0] pciw_whole_waddr = pciw_waddr ; wire [(`PCI_FIFO_RAM_ADDR_LENGTH-1):0] pciw_whole_raddr = pciw_raddr ; wire [(`PCI_FIFO_RAM_ADDR_LENGTH-1):0] pcir_whole_waddr = pcir_waddr ; wire [(`PCI_FIFO_RAM_ADDR_LENGTH-1):0] pcir_whole_raddr = pcir_raddr ; wire pciw_read_enable = 1'b1 ; wire pcir_read_enable = 1'b1 ; `ifdef PCI_BIST wire mbist_so_o_internal ; // wires for connection of debug ports on two rams wire mbist_si_i_internal = mbist_so_o_internal ; `endif // instantiate and connect two generic rams - one for pci write fifo and one for pci read fifo pci_pci_tpram #(`PCI_FIFO_RAM_ADDR_LENGTH, 40) pciw_fifo_storage ( // Generic synchronous two-port RAM interface .clk_a(pci_clock_in), .rst_a(reset_in), .ce_a(1'b1), .we_a(pciw_wallow), .oe_a(1'b1), .addr_a(pciw_whole_waddr), .di_a(dpram_portA_input), .do_a(), .clk_b(wb_clock_in), .rst_b(reset_in), .ce_b(pciw_read_enable), .we_b(1'b0), .oe_b(1'b1), .addr_b(pciw_whole_raddr), .di_b(40'h00_0000_0000), .do_b(dpram_portB_output) `ifdef PCI_BIST , .mbist_si_i (mbist_si_i), .mbist_so_o (mbist_so_o_internal), .mbist_ctrl_i (mbist_ctrl_i) `endif ); pci_pci_tpram #(`PCI_FIFO_RAM_ADDR_LENGTH, 40) pcir_fifo_storage ( // Generic synchronous two-port RAM interface .clk_a(wb_clock_in), .rst_a(reset_in), .ce_a(1'b1), .we_a(pcir_wallow), .oe_a(1'b1), .addr_a(pcir_whole_waddr), .di_a(dpram_portB_input), .do_a(), .clk_b(pci_clock_in), .rst_b(reset_in), .ce_b(pcir_read_enable), .we_b(1'b0), .oe_b(1'b1), .addr_b(pcir_whole_raddr), .di_b(40'h00_0000_0000), .do_b(dpram_portA_output) `ifdef PCI_BIST , .mbist_si_i (mbist_si_i_internal), .mbist_so_o (mbist_so_o), .mbist_ctrl_i (mbist_ctrl_i) `endif ); `else // RAM blocks sharing between two fifos /*----------------------------------------------------------------------------------------------------------- Code section under this ifdef is used for implementation where RAM instances are too expensive. In this case one RAM instance is used for both - pci read and pci write fifo. -----------------------------------------------------------------------------------------------------------*/ /*----------------------------------------------------------------------------------------------------------- Address prefix definition - since both FIFOs reside in same RAM instance, storage is separated by MSB addresses. pci write fifo addresses are padded with zeros on the MSB side ( at least one address line must be used for this ), pci read fifo addresses are padded with ones on the right ( at least one ). -----------------------------------------------------------------------------------------------------------*/ wire [(`PCI_FIFO_RAM_ADDR_LENGTH - PCIW_ADDR_LENGTH - 1):0] pciw_addr_prefix = {( `PCI_FIFO_RAM_ADDR_LENGTH - PCIW_ADDR_LENGTH){1'b0}} ; wire [(`PCI_FIFO_RAM_ADDR_LENGTH - PCIR_ADDR_LENGTH - 1):0] pcir_addr_prefix = {( `PCI_FIFO_RAM_ADDR_LENGTH - PCIR_ADDR_LENGTH){1'b1}} ; /*----------------------------------------------------------------------------------------------------------- Port A address generation for RAM instance. RAM instance must be full two port RAM - read and write capability on both sides. Port A is clocked by PCI clock, DIA is input for pciw_fifo, DOA is output for pcir_fifo. Address is multiplexed so operation can be switched between fifos. Default is a read on port. -----------------------------------------------------------------------------------------------------------*/ wire [(`PCI_FIFO_RAM_ADDR_LENGTH-1):0] portA_addr = pciw_wallow ? {pciw_addr_prefix, pciw_waddr} : {pcir_addr_prefix, pcir_raddr} ; /*----------------------------------------------------------------------------------------------------------- Port B is clocked by WISHBONE clock, DIB is input for pcir_fifo, DOB is output for pciw_fifo. Address is multiplexed so operation can be switched between fifos. Default is a read on port. -----------------------------------------------------------------------------------------------------------*/ wire [(`PCI_FIFO_RAM_ADDR_LENGTH-1):0] portB_addr = pcir_wallow ? {pcir_addr_prefix, pcir_waddr} : {pciw_addr_prefix, pciw_raddr} ; wire portA_enable = 1'b1 ; wire portB_enable = 1'b1 ; // instantiate RAM for these two fifos pci_pci_tpram #(`PCI_FIFO_RAM_ADDR_LENGTH, 40) pciu_fifo_storage ( // Generic synchronous two-port RAM interface .clk_a(pci_clock_in), .rst_a(reset_in), .ce_a(portA_enable), .we_a(pciw_wallow), .oe_a(1'b1), .addr_a(portA_addr), .di_a(dpram_portA_input), .do_a(dpram_portA_output), .clk_b(wb_clock_in), .rst_b(reset_in), .ce_b(portB_enable), .we_b(pcir_wallow), .oe_b(1'b1), .addr_b(portB_addr), .di_b(dpram_portB_input), .do_b(dpram_portB_output) `ifdef PCI_BIST , .mbist_si_i (mbist_si_i), .mbist_so_o (mbist_so_o), .mbist_ctrl_i (mbist_ctrl_i) `endif ); `endif /*----------------------------------------------------------------------------------------------------------- Instantiation of two control logic modules - one for PCIW_FIFO and one for PCIR_FIFO -----------------------------------------------------------------------------------------------------------*/ pci_pciw_fifo_control #(PCIW_ADDR_LENGTH) pciw_fifo_ctrl ( .rclock_in(wb_clock_in), .wclock_in(pci_clock_in), .renable_in(pciw_renable_in), .wenable_in(pciw_wenable_in), .reset_in(reset_in), // .flush_in(pciw_flush_in), // flush not used .three_left_out(pciw_three_left_out), .two_left_out(pciw_two_left_out), .almost_full_out(pciw_almost_full_out), .full_out(pciw_full_out), .almost_empty_out(pciw_almost_empty_out), .empty_out(pciw_empty), .waddr_out(pciw_waddr), .raddr_out(pciw_raddr), .rallow_out(pciw_rallow), .wallow_out(pciw_wallow) ); pci_pcir_fifo_control #(PCIR_ADDR_LENGTH) pcir_fifo_ctrl ( .rclock_in(pci_clock_in), .wclock_in(wb_clock_in), .renable_in(pcir_renable_in), .wenable_in(pcir_wenable_in), .reset_in(reset_in), .flush_in(pcir_flush_in), .full_out(pcir_full_out), .almost_empty_out(pcir_almost_empty_out), .empty_out(pcir_empty), .waddr_out(pcir_waddr), .raddr_out(pcir_raddr), .rallow_out(pcir_rallow), .wallow_out(pcir_wallow) ); // in and out transaction counters and grey codes reg [(PCIW_ADDR_LENGTH-2):0] inGreyCount ; reg [(PCIW_ADDR_LENGTH-2):0] outGreyCount ; wire [(PCIW_ADDR_LENGTH-2):0] inNextGreyCount = {pciw_inTransactionCount[(PCIW_ADDR_LENGTH-2)], pciw_inTransactionCount[(PCIW_ADDR_LENGTH-2):1] ^ pciw_inTransactionCount[(PCIW_ADDR_LENGTH-3):0]} ; wire [(PCIW_ADDR_LENGTH-2):0] outNextGreyCount = {pciw_outTransactionCount[(PCIW_ADDR_LENGTH-2)], pciw_outTransactionCount[(PCIW_ADDR_LENGTH-2):1] ^ pciw_outTransactionCount[(PCIW_ADDR_LENGTH-3):0]} ; // input transaction counter is incremented when whole transaction is written to fifo. This is indicated by last control bit written to last transaction location wire in_count_en = pciw_wallow && pciw_last_in ; // output transaction counter is incremented when whole transaction is pulled out of fifo. This is indicated when location with last control bit set is read wire out_count_en = pciw_rallow && pciw_last_out ; always@(posedge pci_clock_in or posedge pciw_clear) begin if (pciw_clear) begin inGreyCount <= 0 ; end else if (in_count_en) inGreyCount <= #`FF_DELAY inNextGreyCount ; end wire [(PCIW_ADDR_LENGTH-2):0] wb_clk_sync_inGreyCount ; reg [(PCIW_ADDR_LENGTH-2):0] wb_clk_inGreyCount ; pci_synchronizer_flop #((PCIW_ADDR_LENGTH - 1), 0) i_synchronizer_reg_inGreyCount ( .data_in (inGreyCount), .clk_out (wb_clock_in), .sync_data_out (wb_clk_sync_inGreyCount), .async_reset (pciw_clear) ) ; always@(posedge wb_clock_in or posedge pciw_clear) begin if (pciw_clear) wb_clk_inGreyCount <= #`FF_DELAY 0 ; else wb_clk_inGreyCount <= # `FF_DELAY wb_clk_sync_inGreyCount ; end always@(posedge wb_clock_in or posedge pciw_clear) begin if (pciw_clear) begin outGreyCount <= #`FF_DELAY 0 ; end else if (out_count_en) outGreyCount <= #`FF_DELAY outNextGreyCount ; end always@(posedge pci_clock_in or posedge pciw_clear) begin if (pciw_clear) pciw_inTransactionCount <= #`FF_DELAY 1 ; else if (in_count_en) pciw_inTransactionCount <= #`FF_DELAY pciw_inTransactionCount + 1'b1 ; end always@(posedge wb_clock_in or posedge pciw_clear) begin if (pciw_clear) pciw_outTransactionCount <= #`FF_DELAY 1 ; else if (out_count_en) pciw_outTransactionCount <= #`FF_DELAY pciw_outTransactionCount + 1'b1 ; end assign pciw_transaction_ready_out = wb_clk_inGreyCount != outGreyCount ; assign pcir_transaction_ready_out = 1'b0 ; endmodule