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[/] [klc32/] [trunk/] [rtl/] [verilog/] [INTA.v] - Blame information for rev 6

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Line No. Rev Author Line
1 2 robfinch
// ============================================================================
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// (C) 2011 Robert Finch
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// All Rights Reserved.
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// robfinch<remove>@opencores.org
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//
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// KLC32 - 32 bit CPU
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// INTA.v - interrupt acknowledge
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//
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// This source file is free software: you can redistribute it and/or modify 
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// it under the terms of the GNU Lesser General Public License as published 
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// by 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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//                                                                          
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// This source file is distributed in the hope that it will be useful,      
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// but WITHOUT ANY WARRANTY; without even the implied warranty of           
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            
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// GNU General Public License for more details.                             
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//                                                                          
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// You should have received a copy of the GNU General Public License        
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// along with this program.  If not, see <http://www.gnu.org/licenses/>.    
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//                                                                          
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// ============================================================================
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//
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INTA:
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        if (!cyc_o) begin
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                fc_o <= 3'b111;
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                inta_o <= 1'b1;
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                cyc_o <= 1'b1;
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                stb_o <= 1'b1;
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                sel_o <= 4'b0001;
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                adr_o <= {27'h7FFFFFF,iplr,2'b00};
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        end
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        else if (vpa_i) begin
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                inta_o <= 1'b0;
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                cyc_o <= 1'b0;
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                stb_o <= 1'b0;
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                sel_o <= 4'b0000;
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                vecnum <= 32'd24 + iplr;
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                state <= FETCH_VECTOR;
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        end
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        else if (ack_i) begin
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                inta_o <= 1'b0;
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                cyc_o <= 1'b0;
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                stb_o <= 1'b0;
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                sel_o <= 4'b0000;
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                vecnum <= dat_i[7:0];
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                state <= FETCH_VECTOR;
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        end
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        else if (err_i) begin
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                inta_o <= 1'b0;
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                cyc_o <= 1'b0;
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                stb_o <= 1'b0;
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                sel_o <= 4'b0000;
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                vecnum <= 32'd24;               // Spurious interrupt
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                state <= FETCH_VECTOR;
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        end
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FETCH_VECTOR:
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        if (!cyc_o) begin
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                fc_o <= 3'b101;
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                cyc_o <= 1'b1;
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                stb_o <= 1'b1;
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                sel_o <= 4'b1111;
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                adr_o <= {vecnum,2'b00};
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        end
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        else if (ack_i) begin
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                cyc_o <= 1'b0;
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                stb_o <= 1'b0;
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                sel_o <= 4'b0000;
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                vector <= dat_i;
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                state <= TRAP1;
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        end
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        // I don't bother with bus error checking here because if the cpu can't read the
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        // vector table, bus error processing won't help.
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