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robfinch |
// ============================================================================
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// __
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// \\__/ o\ (C) 2013 Robert Finch, Stratford
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// \ __ / All rights reserved.
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// \/_// robfinch<remove>@opencores.org
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// ||
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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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`include "rtf65002_defines.v"
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module rtf65002_pcinc8(opcode,suppress_pcinc,inc);
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input [7:0] opcode;
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input [3:0] suppress_pcinc;
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output reg [3:0] inc;
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always @(opcode)
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if (suppress_pcinc==4'hF)
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case(opcode)
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`BRK: inc <= 4'd0;
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`BPL,`BMI,`BCS,`BCC,`BVS,`BVC,`BEQ,`BNE,`BRA: inc <= 4'd2;
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`BRL: inc <= 4'd3;
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`CLC,`SEC,`CLD,`SED,`CLV,`CLI,`SEI: inc <= 4'd1;
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`TAS,`TSA,`TAY,`TYA,`TAX,`TXA,`TSX,`TXS,`TYX,`TXY: inc <= 4'd1;
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`INY,`DEY,`INX,`DEX,`INA,`DEA: inc <= 4'd1;
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`NAT: inc <= 4'd1;
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`STP,`WAI: inc <= 4'd1;
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`JMP,`JML,`JMP_IND,`JMP_INDX,
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`RTS,`RTL,`RTI: inc <= 4'd0;
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`JSR,`JSR_INDX: inc <= 4'd2;
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`JSL: inc <= 4'd4;
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`NOP: inc <= 4'd1;
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`ADC_IMM,`SBC_IMM,`CMP_IMM,`AND_IMM,`ORA_IMM,`EOR_IMM,`LDA_IMM: inc <= 4'd2;
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`LDX_IMM,`LDY_IMM,`CPX_IMM,`CPY_IMM,`BIT_IMM: inc <= 4'd2;
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`TRB_ZP,`TSB_ZP,
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`ADC_ZP,`SBC_ZP,`CMP_ZP,`AND_ZP,`ORA_ZP,`EOR_ZP,`LDA_ZP,`STA_ZP: inc <= 4'd2;
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`LDY_ZP,`LDX_ZP,`STY_ZP,`STX_ZP,`CPX_ZP,`CPY_ZP,`BIT_ZP,`STZ_ZP: inc <= 4'd2;
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`ASL_ZP,`ROL_ZP,`LSR_ZP,`ROR_ZP,`INC_ZP,`DEC_ZP: inc <= 4'd2;
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`ADC_ZPX,`SBC_ZPX,`CMP_ZPX,`AND_ZPX,`ORA_ZPX,`EOR_ZPX,`LDA_ZPX,`STA_ZPX: inc <= 4'd2;
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`LDY_ZPX,`STY_ZPX,`BIT_ZPX,`STZ_ZPX: inc <= 4'd2;
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`ASL_ZPX,`ROL_ZPX,`LSR_ZPX,`ROR_ZPX,`INC_ZPX,`DEC_ZPX: inc <= 4'd2;
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`LDX_ZPY,`STX_ZPY: inc <= 4'd2;
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`ADC_I,`SBC_I,`AND_I,`ORA_I,`EOR_I,`CMP_I,`LDA_I,`STA_I,
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`ADC_IX,`SBC_IX,`CMP_IX,`AND_IX,`OR_IX,`EOR_IX,`LDA_IX,`STA_IX: inc <= 4'd2;
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`ADC_IY,`SBC_IY,`CMP_IY,`AND_IY,`OR_IY,`EOR_IY,`LDA_IY,`STA_IY: inc <= 4'd2;
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`TRB_ABS,`TSB_ABS,
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`ADC_ABS,`SBC_ABS,`CMP_ABS,`AND_ABS,`OR_ABS,`EOR_ABS,`LDA_ABS,`STA_ABS: inc <= 4'd3;
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`LDX_ABS,`LDY_ABS,`STX_ABS,`STY_ABS,`CPX_ABS,`CPY_ABS,`BIT_ABS,`STZ_ABS: inc <= 4'd3;
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`ASL_ABS,`ROL_ABS,`LSR_ABS,`ROR_ABS,`INC_ABS,`DEC_ABS: inc <= 4'd3;
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`ADC_ABSX,`SBC_ABSX,`CMP_ABSX,`AND_ABSX,`OR_ABSX,`EOR_ABSX,`LDA_ABSX,`STA_ABSX: inc <= 4'd3;
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`LDY_ABSX,`BIT_ABSX,`STZ_ABSX: inc <= 4'd3;
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`ASL_ABSX,`ROL_ABSX,`LSR_ABSX,`ROR_ABSX,`INC_ABSX,`DEC_ABSX: inc <= 4'd3;
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`ADC_ABSY,`SBC_ABSY,`CMP_ABSY,`AND_ABSY,`ORA_ABSY,`EOR_ABSY,`LDA_ABSY,`STA_ABSY: inc <= 4'd3;
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`LDX_ABSY: inc <= 4'd3;
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`ASL_ACC,`LSR_ACC,`ROR_ACC,`ROL_ACC: inc <= 4'd1;
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`PHP,`PHA,`PHX,`PHY,`PLP,`PLA,`PLX,`PLY: inc <= 4'd1;
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default: inc <= 4'd0; // unimplemented instruction
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endcase
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else
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inc <= 4'd0;
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endmodule
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