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////  8051 compare                                                ////

////                                                              ////

////  This file is part of the 8051 cores project                 ////

////  http://www.opencores.org/cores/8051/                        ////

////                                                              ////

////  Description                                                 ////

////   compares selected inputs and set eq to 1 if they are equal ////

////   Is used for conditional jumps.                             ////

////                                                              ////

////  To Do:                                                      ////

////   replace CSS_AZ with CSS_DES                                ////

////                                                              ////

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

////      - Simon Teran, simont@opencores.org                     ////

////                                                              ////

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//// Copyright (C) 2000 Authors and 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                     ////

////                                                              ////

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//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

//

// synopsys translate_off

`include "oc8051_timescale.v"

// synopsys translate_on

`include "oc8051_defines.v"

module oc8051_comp (sel, b_in, cy, acc, des, eq);

//

// sel          (in)  select whithc sourses to compare (look defines.v) [oc8051_decoder.comp_sel]

// b_in         (in)  bit in - output from bit addressable memory space [oc8051_ram_sel.bit_out]

// cy           (in)  carry flag [oc8051_psw.data_out[7] ]

// acc          (in)  accumulator [oc8051_acc.data_out]

// ram          (in)  input from ram [oc8051_ram_sel.out_data]

// op2          (in)  immediate data [oc8051_op_select.op2_out -r]

// des          (in)  destination from alu [oc8051_alu.des1 -r]

// eq           (out) if (src1 == src2) eq = 1  [oc8051_decoder.eq]

//

input [1:0] sel;

input b_in, cy;

input [7:0] acc, des;

output eq;

reg eq;

always @(sel or b_in or cy or acc or des)

begin

  case (sel)

    `OC8051_CSS_AZ : eq = (acc == 8'h00);

    `OC8051_CSS_DES : eq = (des == 8'h00);

    `OC8051_CSS_CY : eq = cy;

    `OC8051_CSS_BIT : eq = b_in;

    default: eq = 1'bx;

  endcase

end

endmodule