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// ============================================================================
//        __
//   \\__/ o\    (C) 2013  Robert Finch, Stratford
//    \  __ /    All rights reserved.
//     \/_//     robfinch<remove>@opencores.org
//       ||
//
// 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 3 of the License, or     
// (at your option) any later version.                                      
//                                                                          
// This source file 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 General Public License for more details.                             
//                                                                          
// You should have received a copy of the GNU General Public License        
// along with this program.  If not, see <http://www.gnu.org/licenses/>.    
//                                                                          
// ============================================================================
//
DECODE:
        begin
                first_ifetch <= `TRUE;
                Rt <= 4'h0;             // Default
                state <= IFETCH;
                pc <= pcp1;
                case(ir[7:0])
                `STP:   begin clk_en <= 1'b0; end
                `NOP:   casex(ir[63:0])
                                {`NOP,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP}:      pc <= pcp8;
                                {8'hxx,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP}:     pc <= pcp7;
                                {16'hxxxx,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP}:       pc <= pcp6;
                                {24'hxxxxxx,`NOP,`NOP,`NOP,`NOP,`NOP}:  pc <= pcp5;
                                {32'hxxxxxxxx,`NOP,`NOP,`NOP,`NOP}:     pc <= pcp4;
                                {40'hxxxxxxxxxx,`NOP,`NOP,`NOP}: pc <= pcp3;
                                {48'hxxxxxxxxxxxx,`NOP,`NOP}:   pc <= pcp2;
                                {56'hxxxxxxxxxxxxxx,`NOP}:      pc <= pcp1;
                                endcase
                `CLC:   begin cf <= 1'b0; end
                `SEC:   begin cf <= 1'b1; end
                `CLV:   begin vf <= 1'b0; end
                `CLI:   begin im <= 1'b0; end
                `CLD:   begin df <= 1'b0; end
                `SED:   begin df <= 1'b1; end
                `SEI:   begin im <= 1'b1; end
                `WAI:   begin wai <= 1'b1; end
                `EMM:   begin em <= 1'b1; end
                `DEX:   begin
                                        res <= x - 32'd1;
                                        // DEX/BNE accelerator
//                                      if (ir[15:8]==`BNE) begin
//                                              if (x!=32'd1) begin
//                                                      if (ir[23:16]==8'h01)
//                                                              pc <= pc + {{16{ir[39]}},ir[39:24]} + 32'd1;
//                                                      else
//                                                              pc <= pc + {{24{ir[23]}},ir[23:16]} + 32'd1;
//                                              end
//                                              else begin
//                                                      if (ir[23:16]==8'h01)
//                                                              pc <= pcp5;
//                                                      else
//                                                              pc <= pcp3;
//                                              end
//                                      end
                                end
                `INX:   begin res <= x + 32'd1; end
                `DEY:   begin res <= y - 32'd1; end
                `INY:   begin res <= y + 32'd1; end
                `DEA:   begin res <= acc - 32'd1; end
                `INA:   begin res <= acc + 32'd1; end
                `TSX,`TSA:      begin res <= isp; end
                `TXS,`TXA,`TXY: begin res <= x; end
                `TAX,`TAY,`TAS: begin res <= acc; end
                `TYA,`TYX:      begin res <= y; end
                `TRS:           begin
                                                res <= rfoa; pc <= pcp2; end
                `TSR:           begin
                                                Rt <= ir[15:12];
                                                case(ir[11:8])
                                                4'h0:   res <= {write_allocate,dcacheOn,icacheOn};
                                                4'h1:   res <= dp;
                                                4'h2:   res <= prod[31:0];
                                                4'h3:   res <= prod[63:32];
                                                4'h4:   res <= tick;
                                                4'h5:   begin res <= lfsr; lfsr <= {lfsr[30:0],lfsr_fb}; end
                                                4'h6:   res <= dp8;
                                                4'h7:   res <= abs8;
                                                4'h8:   res <= {vbr[31:1],nmoi};
                                                4'h9:   res <= derr_address;
                                                4'hE:   res <= {spage[31:8],sp};
                                                4'hF:   res <= isp;
                                                endcase
                                                pc <= pcp2;
                                        end
                `ASL_ACC:       begin res <= {acc,1'b0}; end
                `ROL_ACC:       begin res <= {acc,cf};end
                `LSR_ACC:       begin res <= {acc[0],1'b0,acc[31:1]}; end
                `ROR_ACC:       begin res <= {acc[0],cf,acc[31:1]}; end
 
                `RR:
                        begin
                                state <= IFETCH;
                                case(ir[23:20])
                                `ADD_RR:        begin res <= rfoa + rfob + {31'b0,df&cf}; a <= rfoa; b <= rfob; end
                                `SUB_RR:        begin res <= rfoa - rfob - {31'b0,df&~cf&|ir[19:16]}; a <= rfoa; b <= rfob; end
                                `AND_RR:        begin res <= rfoa & rfob; a <= rfoa; b <= rfob; end     // for bit flags
                                `OR_RR:         begin res <= rfoa | rfob; a <= rfoa; b <= rfob; end
                                `EOR_RR:        begin res <= rfoa ^ rfob; a <= rfoa; b <= rfob; end
                                `MUL_RR:        begin state <= MULDIV1; end
                                `MULS_RR:       begin state <= MULDIV1; end
                                `DIV_RR:        begin state <= MULDIV1; end
                                `DIVS_RR:       begin state <= MULDIV1; end
                                `MOD_RR:        begin state <= MULDIV1; end
                                `MODS_RR:       begin state <= MULDIV1; end
                                `ASL_RRR:       begin a <= rfoa; b <= rfob; state <= CALC; end
                                `LSR_RRR:       begin a <= rfoa; b <= rfob; state <= CALC; end
                                endcase
                                Rt <= ir[19:16];
                                pc <= pcp3;
                        end
                `LD_RR:         begin res <= rfoa; Rt <= ir[15:12]; pc <= pcp2; end
                `ASL_RR:        begin res <= {rfoa,1'b0}; pc <= pcp2; Rt <= ir[15:12]; end
                `ROL_RR:        begin res <= {rfoa,cf}; pc <= pcp2; Rt <= ir[15:12]; end
                `LSR_RR:        begin res <= {rfoa[0],1'b0,rfoa[31:1]}; pc <= pcp2; Rt <= ir[15:12]; end
                `ROR_RR:        begin res <= {rfoa[0],cf,rfoa[31:1]}; pc <= pcp2; Rt <= ir[15:12]; end
                `DEC_RR:        begin res <= rfoa - 32'd1; pc <= pcp2; Rt <= ir[15:12]; end
                `INC_RR:        begin res <= rfoa + 32'd1; pc <= pcp2; Rt <= ir[15:12]; end
 
                `ADD_IMM8:      begin res <= rfoa + {{24{ir[23]}},ir[23:16]} + {31'b0,df&cf}; Rt <= ir[15:12]; pc <= pcp3; a <= rfoa; b <= {{24{ir[23]}},ir[23:16]}; end
                `SUB_IMM8:      begin res <= rfoa - {{24{ir[23]}},ir[23:16]} - {31'b0,df&~cf&|ir[15:12]}; Rt <= ir[15:12]; pc <= pcp3; a <= rfoa; b <= {{24{ir[23]}},ir[23:16]}; end
                `OR_IMM8:       begin res <= rfoa | {{24{ir[23]}},ir[23:16]}; Rt <= ir[15:12]; pc <= pcp3; b <= {{24{ir[23]}},ir[23:16]}; end
                `AND_IMM8:      begin res <= rfoa & {{24{ir[23]}},ir[23:16]}; Rt <= ir[15:12]; pc <= pcp3; b <= {{24{ir[23]}},ir[23:16]}; end
                `EOR_IMM8:      begin res <= rfoa ^ {{24{ir[23]}},ir[23:16]}; Rt <= ir[15:12]; pc <= pcp3; b <= {{24{ir[23]}},ir[23:16]}; end
                `CMP_IMM8:      begin res <= acc - {{24{ir[15]}},ir[15:8]}; Rt <= 4'h0; pc <= pcp2; b <= {{24{ir[15]}},ir[15:8]}; end
                `ASL_IMM8:      begin a <= rfoa; b <= ir[20:16]; Rt <= ir[15:12]; pc <= pcp3; state <= CALC; end
                `LSR_IMM8:      begin a <= rfoa; b <= ir[20:16]; Rt <= ir[15:12]; pc <= pcp3; state <= CALC; end
 
                `ADD_IMM16:     begin res <= rfoa + {{16{ir[31]}},ir[31:16]} + {31'b0,df&cf}; Rt <= ir[15:12]; pc <= pcp4; a <= rfoa; b <= {{16{ir[31]}},ir[31:16]}; end
                `SUB_IMM16:     begin res <= rfoa - {{16{ir[31]}},ir[31:16]} - {31'b0,df&~cf&|ir[15:12]}; Rt <= ir[15:12]; pc <= pcp4; a <= rfoa; b <= {{16{ir[31]}},ir[31:16]}; end
                `OR_IMM16:      begin res <= rfoa | {{16{ir[31]}},ir[31:16]}; Rt <= ir[15:12]; pc <= pcp4; b <= {{16{ir[31]}},ir[31:16]}; end
                `AND_IMM16:     begin res <= rfoa & {{16{ir[31]}},ir[31:16]}; Rt <= ir[15:12]; pc <= pcp4; b <= {{16{ir[31]}},ir[31:16]}; end
                `EOR_IMM16:     begin res <= rfoa ^ {{16{ir[31]}},ir[31:16]}; Rt <= ir[15:12]; pc <= pcp4; b <= {{16{ir[31]}},ir[31:16]}; end
 
                `ADD_IMM32:     begin res <= rfoa + ir[47:16]; Rt <= ir[15:12] + {31'b0,df&cf}; pc <= pcp6; a <= rfoa; b <= ir[47:16]; end
                `SUB_IMM32:     begin res <= rfoa - ir[47:16]; Rt <= ir[15:12] - {31'b0,df&~cf&|ir[15:12]}; pc <= pcp6; a <= rfoa; b <= ir[47:16]; end
                `OR_IMM32:      begin res <= rfoa | ir[47:16]; Rt <= ir[15:12]; pc <= pcp6; b <= ir[47:16]; end
                `AND_IMM32:     begin res <= rfoa & ir[47:16]; Rt <= ir[15:12]; pc <= pcp6; b <= ir[47:16]; end
                `EOR_IMM32:     begin res <= rfoa ^ ir[47:16]; Rt <= ir[15:12]; pc <= pcp6; b <= ir[47:16]; end
 
                `LDX_IMM32,`LDY_IMM32,`LDA_IMM32:       begin res <= ir[39:8]; pc <= pcp5; end
                `LDX_IMM16,`LDA_IMM16:  begin res <= {{16{ir[23]}},ir[23:8]}; pc <= pcp3; end
                `LDX_IMM8,`LDA_IMM8: begin res <= {{24{ir[15]}},ir[15:8]}; pc <= pcp2; end
 
                `SUB_SP8:       begin res <= isp - {{24{ir[15]}},ir[15:8]}; pc <= pcp2; end
                `SUB_SP16:      begin res <= isp - {{16{ir[23]}},ir[23:8]}; pc <= pcp3; end
                `SUB_SP32:      begin res <= isp - ir[39:8]; pc <= pcp5; end
 
                `LDX_ZPX,`LDY_ZPX:
                        begin
                                radr <= zpx32xy_address;
                                pc <= pcp3;
                                load_what <= `WORD_311;
                                state <= LOAD_MAC1;
                        end
                `ORB_ZPX:
                        begin
                                a <= rfoa;
                                Rt <= ir[19:16];
                                radr <= zpx32_address[31:2];
                                radr2LSB <= zpx32_address[1:0];
                                pc <= pcp4;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `LDX_ABS,`LDY_ABS:
                        begin
                                radr <= ir[39:8];
                                pc <= pcp5;
                                load_what <= `WORD_311;
                                state <= LOAD_MAC1;
                        end
                `ORB_ABS:
                        begin
                                a <= rfoa;
                                Rt <= ir[15:12];
                                radr <= ir[47:18];
                                radr2LSB <= ir[17:16];
                                pc <= pcp6;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `LDX_ABSY,`LDY_ABSX:
                        begin
                                radr <= absx32xy_address;
                                pc <= pcp6;
                                load_what <= `WORD_311;
                                state <= LOAD_MAC1;
                        end
                `ORB_ABSX:
                        begin
                                a <= rfoa;
                                Rt <= ir[19:16];
                                radr <= absx32_address[31:2];
                                radr2LSB <= absx32_address[1:0];
                                pc <= pcp7;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `ST_ZPX:
                        begin
                                wadr <= zpx32_address;
                                wdat <= rfoa;
                                pc <= pcp4;
                                state <= STORE1;
                        end
                `STB_ZPX:
                        begin
                                wadr <= zpx32_address[31:2];
                                wadr2LSB <= zpx32_address[1:0];
                                wdat <= {4{rfoa[7:0]}};
                                pc <= pcp4;
                                state <= STORE1;
                        end
                `ST_DSP:
                        begin
                                wadr <= {{24{ir[23]}},ir[23:16]} + isp;
                                wdat <= rfoa;
                                pc <= pcp3;
                                state <= STORE1;
                        end
                `ST_ABS:
                        begin
                                wadr <= ir[47:16];
                                wdat <= rfoa;
                                pc <= pcp6;
                                state <= STORE1;
                        end
                `STB_ABS:
                        begin
                                wadr <= ir[47:18];
                                wadr2LSB <= ir[17:16];
                                wdat <= {4{rfoa[7:0]}};
                                pc <= pcp6;
                                state <= STORE1;
                        end
                `ST_ABSX:
                        begin
                                wadr <= absx32_address;
                                wdat <= rfoa;
                                pc <= pcp7;
                                state <= STORE1;
                        end
                `STB_ABSX:
                        begin
                                wadr <= absx32_address[31:2];
                                wadr2LSB <= absx32_address[1:0];
                                wdat <= {4{rfoa[7:0]}};
                                pc <= pcp7;
                                state <= STORE1;
                        end
                `STX_ZPX:
                        begin
                                wadr <= dp + ir[23:12] + rfoa;
                                wdat <= x;
                                pc <= pcp3;
                                state <= STORE1;
                        end
                `STX_ABS:
                        begin
                                wadr <= ir[39:8];
                                wdat <= x;
                                pc <= pcp5;
                                state <= STORE1;
                        end
                `STY_ZPX:
                        begin
                                wadr <= dp + ir[23:12] + rfoa;
                                wdat <= y;
                                pc <= pcp3;
                                state <= STORE1;
                        end
                `STY_ABS:
                        begin
                                wadr <= ir[39:8];
                                wdat <= y;
                                pc <= pcp5;
                                state <= STORE1;
                        end
                `ADD_ZPX,`SUB_ZPX,`OR_ZPX,`AND_ZPX,`EOR_ZPX:
                        begin
                                a <= rfoa;
                                Rt <= ir[19:16];
                                radr <= zpx32_address;
                                pc <= pcp4;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `ASL_ZPX,`ROL_ZPX,`LSR_ZPX,`ROR_ZPX,`INC_ZPX,`DEC_ZPX:
                        begin
                                radr <= dp + rfoa + ir[23:12];
                                pc <= pcp3;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `ADD_DSP,`SUB_DSP,`OR_DSP,`AND_DSP,`EOR_DSP:
                        begin
                                a <= rfoa;
                                Rt <= ir[15:12];
                                radr <= {{24{ir[23]}},ir[23:16]} + isp;
                                pc <= pcp3;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `ADD_IX,`SUB_IX,`OR_IX,`AND_IX,`EOR_IX,`ST_IX:
                        begin
                                a <= rfoa;
                                if (ir[7:0]!=`ST_IX)     // for ST_IX, Rt=0
                                        Rt <= ir[19:16];
                                pc <= pcp4;
                                radr <= dp + ir[31:20] + rfob;
                                load_what <= `IA_310;
                                state <= LOAD_MAC1;
                        end
                `ADD_RIND,`SUB_RIND,`OR_RIND,`AND_RIND,`EOR_RIND:
                        begin
                                radr <= rfob;
                                a <= rfoa;
                                Rt <= ir[19:16];
                                pc <= pcp3;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `ST_RIND:
                        begin
                                wadr <= rfob;
                                wdat <= rfoa;
                                pc <= pcp2;
                                state <= STORE1;
                        end
                `ADD_IY,`SUB_IY,`OR_IY,`AND_IY,`EOR_IY,`ST_IY:
                        begin
                                a <= rfoa;
                                if (ir[7:0]!=`ST_IY)     // for ST_IY, Rt=0
                                        Rt <= ir[19:16];
                                pc <= pcp4;
                                isIY <= 1'b1;
                                radr <= dp + ir[31:20];
                                load_what <= `IA_310;
                                state <= LOAD_MAC1;
                        end
                `ADD_ABS,`SUB_ABS,`OR_ABS,`AND_ABS,`EOR_ABS:
                        begin
                                a <= rfoa;
                                radr <= ir[47:16];
                                Rt <= ir[15:12];
                                pc <= pcp6;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `ASL_ABS,`ROL_ABS,`LSR_ABS,`ROR_ABS,`INC_ABS,`DEC_ABS:
                        begin
                                radr <= ir[39:8];
                                pc <= pcp5;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `ADD_ABSX,`SUB_ABSX,`OR_ABSX,`AND_ABSX,`EOR_ABSX:
                        begin
                                a <= rfoa;
                                radr <= ir[55:24] + rfob;
                                Rt <= ir[19:16];
                                pc <= pcp7;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `ASL_ABSX,`ROL_ABSX,`LSR_ABSX,`ROR_ABSX,`INC_ABSX,`DEC_ABSX:
                        begin
                                radr <= ir[47:16] + rfob;
                                pc <= pcp6;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `CPX_IMM32:
                        begin
                                res <= x - ir[39:8];
                                pc <= pcp5;
                                state <= IFETCH;
                        end
                `CPY_IMM32:
                        begin
                                res <= y - ir[39:8];
                                pc <= pcp5;
                                state <= IFETCH;
                        end
                `CPX_ZPX:
                        begin
                                radr <= dp + ir[23:12] + rfoa;
                                pc <= pcp3;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `CPY_ZPX:
                        begin
                                radr <= dp + ir[23:12] + rfoa;
                                pc <= pcp3;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `CPX_ABS:
                        begin
                                radr <= ir[39:8];
                                pc <= pcp5;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `CPY_ABS:
                        begin
                                radr <= ir[39:8];
                                pc <= pcp5;
                                load_what <= `WORD_310;
                                state <= LOAD_MAC1;
                        end
                `BRK:
                        begin
                                bf <= 1'b1;
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= pc+2;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b1;
                                sel_o <= 4'hF;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= pc+2;
                                vect <= {vbr[31:9],`BRK_VECTNO,2'b00};
                                state <= IRQ1;
                        end
                `INT0,`INT1:
                        begin
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= pc + 32'd2;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b1;
                                sel_o <= 4'hF;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= pc + 32'd2;
                                vect <= {vbr[31:9],ir[15:7],2'b00};
                                state <= IRQ1;
                        end
                `JMP:
                        begin
                                pc[15:0] <= ir[23:8];
                                state <= IFETCH;
                        end
                `JML:
                        begin
                                pc <= ir[39:8];
                                state <= IFETCH;
                        end
                `JMP_IND:
                        begin
                                radr <= ir[39:8];
                                load_what <= `PC_310;
                                state <= LOAD_MAC1;
                        end
                `JMP_INDX:
                        begin
                                radr <= ir[39:8] + x;
                                load_what <= `PC_310;
                                state <= LOAD_MAC1;
                        end
                `JMP_RIND:
                        begin
                                pc <= rfoa;
                                res <= pc + 32'd2;
                                Rt <= ir[15:12];
                                state <= IFETCH;
                        end
                `JSR:
                        begin
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= suppress_pcinc[0] ? pc + 32'd3 : pc + 32'd2;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b1;
                                sel_o <= 4'hF;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= suppress_pcinc[0] ? pc + 32'd3 : pc + 32'd2;
                                vect <= {pc[31:16],ir[23:8]};
                                state <= JSR1;
                        end
                `JSR_RIND:
                        begin
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= pc + 32'd2;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b1;
                                sel_o <= 4'hF;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= pc + 32'd2;
                                vect <= rfoa;
                                state <= JSR1;
                                $stop;
                        end
                `JSL:
                        begin
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= suppress_pcinc[0] ? pc + 32'd5 : pc + 32'd2;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b1;
                                sel_o <= 4'hF;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= suppress_pcinc[0] ? pc + 32'd5 : pc + 32'd2;
                                vect <= ir[39:8];
                                state <= JSR1;
                        end
                `BSR:
                        begin
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= suppress_pcinc[0] ? pc + 32'd3 : pc + 32'd2;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b1;
                                sel_o <= 4'hF;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= suppress_pcinc[0] ? pc + 32'd3 : pc + 32'd2;
                                vect <= pc + {{16{ir[23]}},ir[23:8]};
                                state <= JSR1;
                        end
                `JSR_INDX:
                        begin
                                radr <= isp - 32'd1;
                                wadr <= isp - 32'd1;
                                wdat <= suppress_pcinc[0] ? pc + 32'd5 : pc + 32'd2;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b1;
                                sel_o <= 4'hF;
                                adr_o <= {isp-32'd1,2'b00};
                                dat_o <= suppress_pcinc[0] ? pc + 32'd5 : pc + 32'd2;
                                state <= JSR_INDX1;
                        end
//              `JSR16:
//                      begin
//                              radr <= isp - 32'd1;
//                              wadr <= isp - 32'd1;
//                              wdat <= pc + 32'd3;
//                              cyc_o <= 1'b1;
//                              stb_o <= 1'b1;
//                              we_o <= 1'b1;
//                              sel_o <= 4'hF;
//                              adr_o <= {isp-32'd1,2'b00};
//                              dat_o <= pc + 32'd3;
//                              state <= JSR161;
//                      end
                `RTS,`RTL:
                                begin
                                radr <= isp;
                                load_what <= `PC_310;
                                state <= LOAD_MAC1;
                                end
                `RTI:   begin
                                radr <= isp;
                                load_what <= `SR_310;
                                state <= LOAD_MAC1;
                                end
                `BEQ,`BNE,`BPL,`BMI,`BCC,`BCS,`BVC,`BVS,`BRA:
                        begin
                                state <= IFETCH;
                                if (ir[15:8]==8'h00) begin
                                        radr <= isp_dec;
                                        wadr <= isp_dec;
                                        wdat <= pc + 32'd2;
                                        cyc_o <= 1'b1;
                                        stb_o <= 1'b1;
                                        we_o <= 1'b1;
                                        sel_o <= 4'hF;
                                        adr_o <= {isp_dec,2'b00};
                                        dat_o <= pc + 32'd2;
                                        vect <= {vbr[31:9],`SLP_VECTNO,2'b00};
                                        state <= IRQ1;
                                end
                                else if (ir[15:8]==8'h1) begin
                                        if (takb)
                                                pc <= pc + {{16{ir[31]}},ir[31:16]};
                                        else
                                                pc <= pcp4;
                                end
                                else begin
                                        if (takb)
                                                pc <= pc + {{24{ir[15]}},ir[15:8]};
                                        else
                                                pc <= pcp2;
                                end
                        end
/*              `BEQ_RR:
                        begin
                                state <= IFETCH;
                                if (ir[23:16]==8'h00) begin
                                        radr <= isp_dec;
                                        wadr <= isp_dec;
                                        wdat <= pc + 32'd2;
                                        cyc_o <= 1'b1;
                                        stb_o <= 1'b1;
                                        we_o <= 1'b1;
                                        sel_o <= 4'hF;
                                        adr_o <= {isp_dec,2'b00};
                                        dat_o <= pc + 32'd2;
                                        vect <= `SLP_VECT;
                                        state <= IRQ1;
                                end
                                else if (ir[23:16]==8'h1) begin
                                        if (rfoa==rfob)
                                                pc <= pc + {{16{ir[39]}},ir[39:24]};
                                        else
                                                pc <= pc + 32'd5;
                                end
                                else begin
                                        if (takb)
                                                pc <= pc + {{24{ir[23]}},ir[23:16]};
                                        else
                                                pc <= pc + 32'd3;
                                end
                        end*/
                `BRL:
                        begin
                                if (ir[23:8]==16'h0000) begin
                                        radr <= isp_dec;
                                        wadr <= isp_dec;
                                        wdat <= suppress_pcinc[0] ? pc + 32'd3 : pc + 32'd2;
                                        cyc_o <= 1'b1;
                                        stb_o <= 1'b1;
                                        we_o <= 1'b1;
                                        sel_o <= 4'hF;
                                        adr_o <= {isp_dec,2'b00};
                                        dat_o <= suppress_pcinc[0] ? pc + 32'd3 : pc + 32'd2;
                                        vect <= {vbr[31:9],`SLP_VECTNO,2'b00};
                                        state <= IRQ1;
                                end
                                else begin
                                        pc <= pc + {{16{ir[23]}},ir[23:8]};
                                        state <= IFETCH;
                                end
                        end
                `EXEC,`ATNI:
                        begin
                                exbuf[31:0] <= rfoa;
                                exbuf[63:32] <= rfob;
                                pc <= pc + 32'd2;
                                state <= IFETCH;
                        end
                `PHP:
                        begin
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                sel_o <= 4'hF;
                                we_o <= 1'b1;
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= sr;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= sr;
                                isp <= isp_dec;
                                state <= STORE2;
                        end
                `PHA:
                        begin
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                sel_o <= 4'hF;
                                we_o <= 1'b1;
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= acc;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= acc;
                                isp <= isp_dec;
                                state <= STORE2;
                        end
                `PHX:
                        begin
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                sel_o <= 4'hF;
                                we_o <= 1'b1;
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= x;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= x;
                                isp <= isp_dec;
                                state <= STORE2;
                        end
                `PHY:
                        begin
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                sel_o <= 4'hF;
                                we_o <= 1'b1;
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= y;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= y;
                                isp <= isp_dec;
                                state <= STORE2;
                        end
                `PUSH:
                        begin
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                sel_o <= 4'hF;
                                we_o <= 1'b1;
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= rfoa;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= rfoa;
                                state <= STORE2;
                                isp <= isp_dec;
                                pc <= pcp2;
                        end
                `PLP:
                        begin
                                radr <= isp;
                                load_what <= `SR_310;
                                state <= LOAD_MAC1;
                        end
                `PLA,`PLX,`PLY:
                        begin
                                radr <= isp;
                                isp <= isp_inc;
                                load_what <= `WORD_311;
                                state <= LOAD_MAC1;
                        end
                `POP:
                        begin
                                Rt <= ir[15:12];
                                radr <= isp;
                                isp <= isp_inc;
                                load_what <= `WORD_311;
                                state <= LOAD_MAC1;
                                pc <= pcp2;
                        end
//              `MVN:   state <= MVN1;
//              `MVP:   state <= MVP1;
                default:        // unimplemented opcode
                        begin
                                radr <= isp_dec;
                                wadr <= isp_dec;
                                wdat <= suppress_pcinc[0] ? pc + 32'd1 : pc + 32'd2;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b1;
                                sel_o <= 4'hF;
                                adr_o <= {isp_dec,2'b00};
                                dat_o <= suppress_pcinc[0] ? pc + 32'd1 : pc + 32'd2;
                                vect <= {vbr[31:9],9'd495,2'b00};
                                state <= IRQ1;
                        end
                endcase
        end

Line No.	Rev	Author	Line
1	20	robfinch	`// ============================================================================`
2			`// __`
3			`// \\__/ o\ (C) 2013 Robert Finch, Stratford`
4			`// \ __ / All rights reserved.`
5			`// \/_// robfinch<remove>@opencores.org`
6			`// \|\|`
7			`//`
8			`// This source file is free software: you can redistribute it and/or modify`
9			`// it under the terms of the GNU Lesser General Public License as published`
10			`// by the Free Software Foundation, either version 3 of the License, or`
11			`// (at your option) any later version.`
12			`//`
13			`// This source file is distributed in the hope that it will be useful,`
14			`// but WITHOUT ANY WARRANTY; without even the implied warranty of`
15			`// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the`
16			`// GNU General Public License for more details.`
17			`//`
18			`// You should have received a copy of the GNU General Public License`
19			`// along with this program. If not, see <http://www.gnu.org/licenses/>.`
20			`//`
21			`// ============================================================================`
22			`//`
23			`DECODE:`
24			`begin`
25			first_ifetch <= `TRUE;
26			`Rt <= 4'h0; // Default`
27			`state <= IFETCH;`
28	25	robfinch	`pc <= pcp1;`
29	20	robfinch	`case(ir[7:0])`
30	25	robfinch	`STP: begin clk_en <= 1'b0; end
31			`NOP: casex(ir[63:0])
32			{`NOP,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP}: pc <= pcp8;
33			{8'hxx,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP}: pc <= pcp7;
34			{16'hxxxx,`NOP,`NOP,`NOP,`NOP,`NOP,`NOP}: pc <= pcp6;
35			{24'hxxxxxx,`NOP,`NOP,`NOP,`NOP,`NOP}: pc <= pcp5;
36			{32'hxxxxxxxx,`NOP,`NOP,`NOP,`NOP}: pc <= pcp4;
37			{40'hxxxxxxxxxx,`NOP,`NOP,`NOP}: pc <= pcp3;
38			{48'hxxxxxxxxxxxx,`NOP,`NOP}: pc <= pcp2;
39			{56'hxxxxxxxxxxxxxx,`NOP}: pc <= pcp1;
40			`endcase`
41			`CLC: begin cf <= 1'b0; end
42			`SEC: begin cf <= 1'b1; end
43			`CLV: begin vf <= 1'b0; end
44			`CLI: begin im <= 1'b0; end
45			`CLD: begin df <= 1'b0; end
46			`SED: begin df <= 1'b1; end
47			`SEI: begin im <= 1'b1; end
48			`WAI: begin wai <= 1'b1; end
49			`EMM: begin em <= 1'b1; end
50			`DEX: begin
51			`res <= x - 32'd1;`
52			`// DEX/BNE accelerator`
53			// if (ir[15:8]==`BNE) begin
54			`// if (x!=32'd1) begin`
55			`// if (ir[23:16]==8'h01)`
56			`// pc <= pc + {{16{ir[39]}},ir[39:24]} + 32'd1;`
57			`// else`
58			`// pc <= pc + {{24{ir[23]}},ir[23:16]} + 32'd1;`
59			`// end`
60			`// else begin`
61			`// if (ir[23:16]==8'h01)`
62			`// pc <= pcp5;`
63			`// else`
64			`// pc <= pcp3;`
65			`// end`
66			`// end`
67			`end`
68			`INX: begin res <= x + 32'd1; end
69			`DEY: begin res <= y - 32'd1; end
70			`INY: begin res <= y + 32'd1; end
71			`DEA: begin res <= acc - 32'd1; end
72			`INA: begin res <= acc + 32'd1; end
73			`TSX,`TSA: begin res <= isp; end
74			`TXS,`TXA,`TXY: begin res <= x; end
75			`TAX,`TAY,`TAS: begin res <= acc; end
76			`TYA,`TYX: begin res <= y; end
77	20	robfinch	`TRS: begin
78	25	robfinch	`res <= rfoa; pc <= pcp2; end`
79	20	robfinch	`TSR: begin
80			`Rt <= ir[15:12];`
81			`case(ir[11:8])`
82			`4'h0: res <= {write_allocate,dcacheOn,icacheOn};`
83			`4'h1: res <= dp;`
84			`4'h2: res <= prod[31:0];`
85			`4'h3: res <= prod[63:32];`
86			`4'h4: res <= tick;`
87			`4'h5: begin res <= lfsr; lfsr <= {lfsr[30:0],lfsr_fb}; end`
88			`4'h6: res <= dp8;`
89			`4'h7: res <= abs8;`
90			`4'h8: res <= {vbr[31:1],nmoi};`
91	23	robfinch	`4'h9: res <= derr_address;`
92	20	robfinch	`4'hE: res <= {spage[31:8],sp};`
93			`4'hF: res <= isp;`
94			`endcase`
95	25	robfinch	`pc <= pcp2;`
96	20	robfinch	`end`
97	25	robfinch	`ASL_ACC: begin res <= {acc,1'b0}; end
98			`ROL_ACC: begin res <= {acc,cf};end
99			`LSR_ACC: begin res <= {acc[0],1'b0,acc[31:1]}; end
100			`ROR_ACC: begin res <= {acc[0],cf,acc[31:1]}; end
101	20	robfinch
102			`RR:
103			`begin`
104			`state <= IFETCH;`
105			`case(ir[23:20])`
106	21	robfinch	`ADD_RR: begin res <= rfoa + rfob + {31'b0,df&cf}; a <= rfoa; b <= rfob; end
107			`SUB_RR: begin res <= rfoa - rfob - {31'b0,df&~cf&\|ir[19:16]}; a <= rfoa; b <= rfob; end
108	20	robfinch	`AND_RR: begin res <= rfoa & rfob; a <= rfoa; b <= rfob; end // for bit flags
109			`OR_RR: begin res <= rfoa \| rfob; a <= rfoa; b <= rfob; end
110			`EOR_RR: begin res <= rfoa ^ rfob; a <= rfoa; b <= rfob; end
111			`MUL_RR: begin state <= MULDIV1; end
112			`MULS_RR: begin state <= MULDIV1; end
113			`DIV_RR: begin state <= MULDIV1; end
114			`DIVS_RR: begin state <= MULDIV1; end
115			`MOD_RR: begin state <= MULDIV1; end
116			`MODS_RR: begin state <= MULDIV1; end
117			`ASL_RRR: begin a <= rfoa; b <= rfob; state <= CALC; end
118			`LSR_RRR: begin a <= rfoa; b <= rfob; state <= CALC; end
119			`endcase`
120			`Rt <= ir[19:16];`
121	25	robfinch	`pc <= pcp3;`
122	20	robfinch	`end`
123	25	robfinch	`LD_RR: begin res <= rfoa; Rt <= ir[15:12]; pc <= pcp2; end
124			`ASL_RR: begin res <= {rfoa,1'b0}; pc <= pcp2; Rt <= ir[15:12]; end
125			`ROL_RR: begin res <= {rfoa,cf}; pc <= pcp2; Rt <= ir[15:12]; end
126			`LSR_RR: begin res <= {rfoa[0],1'b0,rfoa[31:1]}; pc <= pcp2; Rt <= ir[15:12]; end
127			`ROR_RR: begin res <= {rfoa[0],cf,rfoa[31:1]}; pc <= pcp2; Rt <= ir[15:12]; end
128			`DEC_RR: begin res <= rfoa - 32'd1; pc <= pcp2; Rt <= ir[15:12]; end
129			`INC_RR: begin res <= rfoa + 32'd1; pc <= pcp2; Rt <= ir[15:12]; end
130	20	robfinch
131	25	robfinch	`ADD_IMM8: begin res <= rfoa + {{24{ir[23]}},ir[23:16]} + {31'b0,df&cf}; Rt <= ir[15:12]; pc <= pcp3; a <= rfoa; b <= {{24{ir[23]}},ir[23:16]}; end
132			`SUB_IMM8: begin res <= rfoa - {{24{ir[23]}},ir[23:16]} - {31'b0,df&~cf&\|ir[15:12]}; Rt <= ir[15:12]; pc <= pcp3; a <= rfoa; b <= {{24{ir[23]}},ir[23:16]}; end
133			`OR_IMM8: begin res <= rfoa \| {{24{ir[23]}},ir[23:16]}; Rt <= ir[15:12]; pc <= pcp3; b <= {{24{ir[23]}},ir[23:16]}; end
134			`AND_IMM8: begin res <= rfoa & {{24{ir[23]}},ir[23:16]}; Rt <= ir[15:12]; pc <= pcp3; b <= {{24{ir[23]}},ir[23:16]}; end
135			`EOR_IMM8: begin res <= rfoa ^ {{24{ir[23]}},ir[23:16]}; Rt <= ir[15:12]; pc <= pcp3; b <= {{24{ir[23]}},ir[23:16]}; end
136			`CMP_IMM8: begin res <= acc - {{24{ir[15]}},ir[15:8]}; Rt <= 4'h0; pc <= pcp2; b <= {{24{ir[15]}},ir[15:8]}; end
137			`ASL_IMM8: begin a <= rfoa; b <= ir[20:16]; Rt <= ir[15:12]; pc <= pcp3; state <= CALC; end
138			`LSR_IMM8: begin a <= rfoa; b <= ir[20:16]; Rt <= ir[15:12]; pc <= pcp3; state <= CALC; end
139	20	robfinch
140	25	robfinch	`ADD_IMM16: begin res <= rfoa + {{16{ir[31]}},ir[31:16]} + {31'b0,df&cf}; Rt <= ir[15:12]; pc <= pcp4; a <= rfoa; b <= {{16{ir[31]}},ir[31:16]}; end
141			`SUB_IMM16: begin res <= rfoa - {{16{ir[31]}},ir[31:16]} - {31'b0,df&~cf&\|ir[15:12]}; Rt <= ir[15:12]; pc <= pcp4; a <= rfoa; b <= {{16{ir[31]}},ir[31:16]}; end
142			`OR_IMM16: begin res <= rfoa \| {{16{ir[31]}},ir[31:16]}; Rt <= ir[15:12]; pc <= pcp4; b <= {{16{ir[31]}},ir[31:16]}; end
143			`AND_IMM16: begin res <= rfoa & {{16{ir[31]}},ir[31:16]}; Rt <= ir[15:12]; pc <= pcp4; b <= {{16{ir[31]}},ir[31:16]}; end
144			`EOR_IMM16: begin res <= rfoa ^ {{16{ir[31]}},ir[31:16]}; Rt <= ir[15:12]; pc <= pcp4; b <= {{16{ir[31]}},ir[31:16]}; end
145	20	robfinch
146	25	robfinch	`ADD_IMM32: begin res <= rfoa + ir[47:16]; Rt <= ir[15:12] + {31'b0,df&cf}; pc <= pcp6; a <= rfoa; b <= ir[47:16]; end
147			`SUB_IMM32: begin res <= rfoa - ir[47:16]; Rt <= ir[15:12] - {31'b0,df&~cf&\|ir[15:12]}; pc <= pcp6; a <= rfoa; b <= ir[47:16]; end
148			`OR_IMM32: begin res <= rfoa \| ir[47:16]; Rt <= ir[15:12]; pc <= pcp6; b <= ir[47:16]; end
149			`AND_IMM32: begin res <= rfoa & ir[47:16]; Rt <= ir[15:12]; pc <= pcp6; b <= ir[47:16]; end
150			`EOR_IMM32: begin res <= rfoa ^ ir[47:16]; Rt <= ir[15:12]; pc <= pcp6; b <= ir[47:16]; end
151	20	robfinch
152	25	robfinch	`LDX_IMM32,`LDY_IMM32,`LDA_IMM32: begin res <= ir[39:8]; pc <= pcp5; end
153			`LDX_IMM16,`LDA_IMM16: begin res <= {{16{ir[23]}},ir[23:8]}; pc <= pcp3; end
154			`LDX_IMM8,`LDA_IMM8: begin res <= {{24{ir[15]}},ir[15:8]}; pc <= pcp2; end
155	20	robfinch
156	25	robfinch	`SUB_SP8: begin res <= isp - {{24{ir[15]}},ir[15:8]}; pc <= pcp2; end
157			`SUB_SP16: begin res <= isp - {{16{ir[23]}},ir[23:8]}; pc <= pcp3; end
158			`SUB_SP32: begin res <= isp - ir[39:8]; pc <= pcp5; end
159	23	robfinch
160	20	robfinch	`LDX_ZPX,`LDY_ZPX:
161			`begin`
162			`radr <= zpx32xy_address;`
163	25	robfinch	`pc <= pcp3;`
164	21	robfinch	load_what <= `WORD_311;
165			`state <= LOAD_MAC1;`
166	20	robfinch	`end`
167			`ORB_ZPX:
168			`begin`
169			`a <= rfoa;`
170			`Rt <= ir[19:16];`
171			`radr <= zpx32_address[31:2];`
172			`radr2LSB <= zpx32_address[1:0];`
173	25	robfinch	`pc <= pcp4;`
174	21	robfinch	load_what <= `WORD_310;
175			`state <= LOAD_MAC1;`
176	20	robfinch	`end`
177			`LDX_ABS,`LDY_ABS:
178			`begin`
179			`radr <= ir[39:8];`
180	25	robfinch	`pc <= pcp5;`
181	21	robfinch	load_what <= `WORD_311;
182			`state <= LOAD_MAC1;`
183	20	robfinch	`end`
184			`ORB_ABS:
185			`begin`
186			`a <= rfoa;`
187			`Rt <= ir[15:12];`
188			`radr <= ir[47:18];`
189			`radr2LSB <= ir[17:16];`
190	25	robfinch	`pc <= pcp6;`
191	21	robfinch	load_what <= `WORD_310;
192			`state <= LOAD_MAC1;`
193	20	robfinch	`end`
194			`LDX_ABSY,`LDY_ABSX:
195			`begin`
196			`radr <= absx32xy_address;`
197	25	robfinch	`pc <= pcp6;`
198	21	robfinch	load_what <= `WORD_311;
199			`state <= LOAD_MAC1;`
200	20	robfinch	`end`
201			`ORB_ABSX:
202			`begin`
203			`a <= rfoa;`
204			`Rt <= ir[19:16];`
205			`radr <= absx32_address[31:2];`
206			`radr2LSB <= absx32_address[1:0];`
207	25	robfinch	`pc <= pcp7;`
208	21	robfinch	load_what <= `WORD_310;
209			`state <= LOAD_MAC1;`
210	20	robfinch	`end`
211			`ST_ZPX:
212			`begin`
213			`wadr <= zpx32_address;`
214			`wdat <= rfoa;`
215	25	robfinch	`pc <= pcp4;`
216	20	robfinch	`state <= STORE1;`
217			`end`
218			`STB_ZPX:
219			`begin`
220			`wadr <= zpx32_address[31:2];`
221			`wadr2LSB <= zpx32_address[1:0];`
222	25	robfinch	`wdat <= {4{rfoa[7:0]}};`
223			`pc <= pcp4;`
224	20	robfinch	`state <= STORE1;`
225			`end`
226	23	robfinch	`ST_DSP:
227			`begin`
228			`wadr <= {{24{ir[23]}},ir[23:16]} + isp;`
229			`wdat <= rfoa;`
230	25	robfinch	`pc <= pcp3;`
231	23	robfinch	`state <= STORE1;`
232			`end`
233	20	robfinch	`ST_ABS:
234			`begin`
235			`wadr <= ir[47:16];`
236			`wdat <= rfoa;`
237	25	robfinch	`pc <= pcp6;`
238	20	robfinch	`state <= STORE1;`
239			`end`
240			`STB_ABS:
241			`begin`
242			`wadr <= ir[47:18];`
243			`wadr2LSB <= ir[17:16];`
244			`wdat <= {4{rfoa[7:0]}};`
245	25	robfinch	`pc <= pcp6;`
246	20	robfinch	`state <= STORE1;`
247			`end`
248			`ST_ABSX:
249			`begin`
250			`wadr <= absx32_address;`
251			`wdat <= rfoa;`
252	25	robfinch	`pc <= pcp7;`
253	20	robfinch	`state <= STORE1;`
254			`end`
255			`STB_ABSX:
256			`begin`
257			`wadr <= absx32_address[31:2];`
258			`wadr2LSB <= absx32_address[1:0];`
259			`wdat <= {4{rfoa[7:0]}};`
260	25	robfinch	`pc <= pcp7;`
261	20	robfinch	`state <= STORE1;`
262			`end`
263			`STX_ZPX:
264			`begin`
265			`wadr <= dp + ir[23:12] + rfoa;`
266			`wdat <= x;`
267	25	robfinch	`pc <= pcp3;`
268	20	robfinch	`state <= STORE1;`
269			`end`
270			`STX_ABS:
271			`begin`
272			`wadr <= ir[39:8];`
273			`wdat <= x;`
274	25	robfinch	`pc <= pcp5;`
275	20	robfinch	`state <= STORE1;`
276			`end`
277			`STY_ZPX:
278			`begin`
279			`wadr <= dp + ir[23:12] + rfoa;`
280			`wdat <= y;`
281	25	robfinch	`pc <= pcp3;`
282	20	robfinch	`state <= STORE1;`
283			`end`
284			`STY_ABS:
285			`begin`
286			`wadr <= ir[39:8];`
287			`wdat <= y;`
288	25	robfinch	`pc <= pcp5;`
289	20	robfinch	`state <= STORE1;`
290			`end`
291			`ADD_ZPX,`SUB_ZPX,`OR_ZPX,`AND_ZPX,`EOR_ZPX:
292			`begin`
293			`a <= rfoa;`
294			`Rt <= ir[19:16];`
295			`radr <= zpx32_address;`
296	25	robfinch	`pc <= pcp4;`
297	21	robfinch	load_what <= `WORD_310;
298			`state <= LOAD_MAC1;`
299	20	robfinch	`end`
300			`ASL_ZPX,`ROL_ZPX,`LSR_ZPX,`ROR_ZPX,`INC_ZPX,`DEC_ZPX:
301			`begin`
302			`radr <= dp + rfoa + ir[23:12];`
303	25	robfinch	`pc <= pcp3;`
304	21	robfinch	load_what <= `WORD_310;
305			`state <= LOAD_MAC1;`
306	20	robfinch	`end`
307	23	robfinch	`ADD_DSP,`SUB_DSP,`OR_DSP,`AND_DSP,`EOR_DSP:
308			`begin`
309			`a <= rfoa;`
310			`Rt <= ir[15:12];`
311			`radr <= {{24{ir[23]}},ir[23:16]} + isp;`
312	25	robfinch	`pc <= pcp3;`
313	23	robfinch	load_what <= `WORD_310;
314			`state <= LOAD_MAC1;`
315			`end`
316	20	robfinch	`ADD_IX,`SUB_IX,`OR_IX,`AND_IX,`EOR_IX,`ST_IX:
317			`begin`
318			`a <= rfoa;`
319	25	robfinch	if (ir[7:0]!=`ST_IX) // for ST_IX, Rt=0
320	20	robfinch	`Rt <= ir[19:16];`
321	25	robfinch	`pc <= pcp4;`
322	20	robfinch	`radr <= dp + ir[31:20] + rfob;`
323	21	robfinch	load_what <= `IA_310;
324			`state <= LOAD_MAC1;`
325	20	robfinch	`end`
326	25	robfinch	`ADD_RIND,`SUB_RIND,`OR_RIND,`AND_RIND,`EOR_RIND:
327	20	robfinch	`begin`
328			`radr <= rfob;`
329			`a <= rfoa;`
330	25	robfinch	`Rt <= ir[19:16];`
331			`pc <= pcp3;`
332			load_what <= `WORD_310;
333			`state <= LOAD_MAC1;`
334	20	robfinch	`end`
335	25	robfinch	`ST_RIND:
336			`begin`
337			`wadr <= rfob;`
338			`wdat <= rfoa;`
339			`pc <= pcp2;`
340			`state <= STORE1;`
341			`end`
342	20	robfinch	`ADD_IY,`SUB_IY,`OR_IY,`AND_IY,`EOR_IY,`ST_IY:
343			`begin`
344			`a <= rfoa;`
345	25	robfinch	if (ir[7:0]!=`ST_IY) // for ST_IY, Rt=0
346	20	robfinch	`Rt <= ir[19:16];`
347	25	robfinch	`pc <= pcp4;`
348	21	robfinch	`isIY <= 1'b1;`
349	20	robfinch	`radr <= dp + ir[31:20];`
350	21	robfinch	load_what <= `IA_310;
351			`state <= LOAD_MAC1;`
352	20	robfinch	`end`
353			`ADD_ABS,`SUB_ABS,`OR_ABS,`AND_ABS,`EOR_ABS:
354			`begin`
355			`a <= rfoa;`
356			`radr <= ir[47:16];`
357			`Rt <= ir[15:12];`
358	25	robfinch	`pc <= pcp6;`
359	21	robfinch	load_what <= `WORD_310;
360			`state <= LOAD_MAC1;`
361	20	robfinch	`end`
362			`ASL_ABS,`ROL_ABS,`LSR_ABS,`ROR_ABS,`INC_ABS,`DEC_ABS:
363			`begin`
364			`radr <= ir[39:8];`
365	25	robfinch	`pc <= pcp5;`
366	21	robfinch	load_what <= `WORD_310;
367			`state <= LOAD_MAC1;`
368	20	robfinch	`end`
369			`ADD_ABSX,`SUB_ABSX,`OR_ABSX,`AND_ABSX,`EOR_ABSX:
370			`begin`
371			`a <= rfoa;`
372			`radr <= ir[55:24] + rfob;`
373			`Rt <= ir[19:16];`
374	25	robfinch	`pc <= pcp7;`
375	21	robfinch	load_what <= `WORD_310;
376			`state <= LOAD_MAC1;`
377	20	robfinch	`end`
378			`ASL_ABSX,`ROL_ABSX,`LSR_ABSX,`ROR_ABSX,`INC_ABSX,`DEC_ABSX:
379			`begin`
380			`radr <= ir[47:16] + rfob;`
381	25	robfinch	`pc <= pcp6;`
382	21	robfinch	load_what <= `WORD_310;
383			`state <= LOAD_MAC1;`
384	20	robfinch	`end`
385			`CPX_IMM32:
386			`begin`
387			`res <= x - ir[39:8];`
388	25	robfinch	`pc <= pcp5;`
389	20	robfinch	`state <= IFETCH;`
390			`end`
391			`CPY_IMM32:
392			`begin`
393			`res <= y - ir[39:8];`
394	25	robfinch	`pc <= pcp5;`
395	20	robfinch	`state <= IFETCH;`
396			`end`
397			`CPX_ZPX:
398			`begin`
399			`radr <= dp + ir[23:12] + rfoa;`
400	25	robfinch	`pc <= pcp3;`
401	21	robfinch	load_what <= `WORD_310;
402			`state <= LOAD_MAC1;`
403	20	robfinch	`end`
404			`CPY_ZPX:
405			`begin`
406			`radr <= dp + ir[23:12] + rfoa;`
407	25	robfinch	`pc <= pcp3;`
408	21	robfinch	load_what <= `WORD_310;
409			`state <= LOAD_MAC1;`
410	20	robfinch	`end`
411			`CPX_ABS:
412			`begin`
413			`radr <= ir[39:8];`
414	25	robfinch	`pc <= pcp5;`
415	21	robfinch	load_what <= `WORD_310;
416			`state <= LOAD_MAC1;`
417	20	robfinch	`end`
418			`CPY_ABS:
419			`begin`
420			`radr <= ir[39:8];`
421	25	robfinch	`pc <= pcp5;`
422	21	robfinch	load_what <= `WORD_310;
423			`state <= LOAD_MAC1;`
424	20	robfinch	`end`
425			`BRK:
426			`begin`
427			`bf <= 1'b1;`
428			`radr <= isp_dec;`
429			`wadr <= isp_dec;`
430	25	robfinch	`wdat <= pc+2;`
431	20	robfinch	`cyc_o <= 1'b1;`
432			`stb_o <= 1'b1;`
433			`we_o <= 1'b1;`
434			`sel_o <= 4'hF;`
435			`adr_o <= {isp_dec,2'b00};`
436	25	robfinch	`dat_o <= pc+2;`
437	20	robfinch	vect <= {vbr[31:9],`BRK_VECTNO,2'b00};
438			`state <= IRQ1;`
439			`end`
440	21	robfinch	`INT0,`INT1:
441			`begin`
442			`radr <= isp_dec;`
443			`wadr <= isp_dec;`
444			`wdat <= pc + 32'd2;`
445			`cyc_o <= 1'b1;`
446			`stb_o <= 1'b1;`
447			`we_o <= 1'b1;`
448			`sel_o <= 4'hF;`
449			`adr_o <= {isp_dec,2'b00};`
450			`dat_o <= pc + 32'd2;`
451			`vect <= {vbr[31:9],ir[15:7],2'b00};`
452			`state <= IRQ1;`
453			`end`
454	20	robfinch	`JMP:
455			`begin`
456			`pc[15:0] <= ir[23:8];`
457			`state <= IFETCH;`
458			`end`
459			`JML:
460			`begin`
461			`pc <= ir[39:8];`
462			`state <= IFETCH;`
463			`end`
464			`JMP_IND:
465			`begin`
466			`radr <= ir[39:8];`
467	21	robfinch	load_what <= `PC_310;
468			`state <= LOAD_MAC1;`
469	20	robfinch	`end`
470			`JMP_INDX:
471			`begin`
472			`radr <= ir[39:8] + x;`
473	21	robfinch	load_what <= `PC_310;
474			`state <= LOAD_MAC1;`
475	20	robfinch	`end`
476			`JMP_RIND:
477			`begin`
478			`pc <= rfoa;`
479			`res <= pc + 32'd2;`
480			`Rt <= ir[15:12];`
481			`state <= IFETCH;`
482			`end`
483			`JSR:
484			`begin`
485			`radr <= isp_dec;`
486			`wadr <= isp_dec;`
487	25	robfinch	`wdat <= suppress_pcinc[0] ? pc + 32'd3 : pc + 32'd2;`
488	20	robfinch	`cyc_o <= 1'b1;`
489			`stb_o <= 1'b1;`
490			`we_o <= 1'b1;`
491			`sel_o <= 4'hF;`
492			`adr_o <= {isp_dec,2'b00};`
493	25	robfinch	`dat_o <= suppress_pcinc[0] ? pc + 32'd3 : pc + 32'd2;`
494	20	robfinch	`vect <= {pc[31:16],ir[23:8]};`
495			`state <= JSR1;`
496			`end`
497			`JSR_RIND:
498			`begin`
499			`radr <= isp_dec;`
500			`wadr <= isp_dec;`

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