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668 lvd 1 
// ZX-Evo Base Configuration (c) NedoPC 2008,2009,2010,2011,2012,2013,2014
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//
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// break function: when CPU M1 address equals to predefined, NMI is generated
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/*
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    This file is part of ZX-Evo Base Configuration firmware.
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    ZX-Evo Base Configuration firmware is free software:
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    you can redistribute it and/or modify it under the terms of
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    the GNU General Public License as published by
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    the Free Software Foundation, either version 3 of the License, or
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    (at your option) any later version.
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    ZX-Evo Base Configuration firmware is distributed in the hope that
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    it will be useful, but WITHOUT ANY WARRANTY; without even
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    the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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    See the GNU General Public License for more details.
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    You should have received a copy of the GNU General Public License
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    along with ZX-Evo Base Configuration firmware.
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    If not, see <http://www.gnu.org/licenses/>.
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*/
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`include "../include/tune.v"
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module zbreak
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(
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        input  wire        fclk,  // global FPGA clock
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        input  wire        rst_n, // system reset
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        input  wire        zpos,
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        input  wire        zneg,
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        input  wire [15:0] a,
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        input  wire        mreq_n,
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        input  wire        m1_n,
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        input  wire        brk_ena,
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        input  wire [15:0] brk_addr,
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        output reg         imm_nmi
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);
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        always @(posedge fclk, negedge rst_n)
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        if( !rst_n )
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                imm_nmi <= 1'b0;
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        else if( zneg && !mreq_n && !m1_n && a==brk_addr && brk_ena && !imm_nmi )
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                imm_nmi <= 1'b1;
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        else
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                imm_nmi <= 1'b0;
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endmodule
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