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//////////////////////////////////////////////////////////////////////

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////  File name: pci_target32_clk_en.v                            ////

////                                                              ////

////  This file is part of the "PCI bridge" project               ////

////  http://www.opencores.org/cores/pci/                         ////

////                                                              ////

////  Author(s):                                                  ////

////      - Tadej Markovic, tadej@opencores.org                   ////

////                                                              ////

////  All additional information is avaliable in the README.txt   ////

////  file.                                                       ////

////                                                              ////

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////                                                              ////

//// Copyright (C) 2000 Tadej Markovic, tadej@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: not supported by cvs2svn $

// Revision 1.3  2002/02/01 15:25:12  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

//

//

// module is used to separate logic which uses criticaly constrained inputs from slower logic.

// It is used to synthesize critical timing logic separately with faster cells or without optimization

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

module pci_target32_clk_en

(

    addr_phase,

    config_access,

    addr_claim_in,

    pci_frame_in,

    state_wait,

    state_transfere,

    state_default,

    clk_enable

);

input           addr_phase ;                    // indicates registered address phase on PCI bus

input           config_access ;                 // indicates configuration access

input           addr_claim_in ;                 // indicates claimed input PCI address

input           pci_frame_in ;                  // critical constrained input signal

input                   state_wait ;                    // indicates WAIT state of FSM

input                   state_transfere ;               // indicates TRANSFERE state of FSM

input                   state_default ;                 // indicates DEFAULT state of FSM

output                  clk_enable ;                    // FSM clock enable output

// clock enable signal when FSM is in IDLE state

wire s_idle_clk_en      =       ((addr_phase && config_access) ||

                                                (addr_phase && ~config_access && addr_claim_in)) ;

// clock enable signal when FSM is in WAIT state or in DEFAULT state

wire s_wait_clk_en      =       (state_wait || state_default) ;

// clock enable signal when FSM is in TRANSFERE state

wire s_tran_clk_en      =       (state_transfere && pci_frame_in) ;

// Clock enable signal for FSM with preserved hierarchy for minimum delay!

assign clk_enable       =       (s_idle_clk_en || s_wait_clk_en || s_tran_clk_en) ;

endmodule