mirror of https://github.com/ariejan/i6502.git
341 lines
8.4 KiB
Go
341 lines
8.4 KiB
Go
package cpu
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// 6502 Addressing modes
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const (
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_ = iota
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absolute
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absoluteX
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absoluteY
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accumulator
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immediate
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implied
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indirect
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indirectX
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indirectY
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relative
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zeropage
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zeropageX
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zeropageY
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)
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// Human readable address modes
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var addressingNames = [...]string{
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"",
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"absolute",
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"absoluteX",
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"absoluteY",
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"accumulator",
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"immediate",
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"implied",
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"(indirect)",
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"(indirect,X)",
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"(indirect),Y",
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"relative",
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"zeropage",
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"zeropageX",
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"zeropageY",
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}
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// 6502 Instruction mnemonics.
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// OpCodes are a combination of an instruction and an addressing mode
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const (
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_ = iota
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adc
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and
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asl
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bcc
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bcs
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beq
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bit
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bmi
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bne
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bpl
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brk
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bvc
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bvs
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clc
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cld
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cli
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clv
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cmp
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cpx
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cpy
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dec
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dex
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dey
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eor
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inc
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inx
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iny
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jmp
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jsr
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lda
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ldx
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ldy
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lsr
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nop
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ora
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pha
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php
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pla
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plp
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rol
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ror
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rti
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rts
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sbc
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sec
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sed
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sei
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sta
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stx
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sty
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tax
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tay
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tsx
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txa
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txs
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tya
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_end
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)
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// Human readable instruction mnemonics
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var instructionNames = [...]string{
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"",
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"ADC",
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"AND",
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"ASL",
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"BCC",
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"BCS",
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"BEQ",
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"BIT",
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"BMI",
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"BNE",
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"BPL",
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"BRK",
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"BVC",
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"BVS",
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"CLC",
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"CLD",
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"CLI",
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"CLV",
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"CMP",
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"CPX",
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"CPY",
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"DEC",
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"DEX",
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"DEY",
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"EOR",
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"INC",
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"INX",
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"INY",
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"JMP",
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"JSR",
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"LDA",
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"LDX",
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"LDY",
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"LSR",
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"NOP",
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"ORA",
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"PHA",
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"PHP",
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"PLA",
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"PLP",
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"ROL",
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"ROR",
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"RTI",
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"RTS",
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"SBC",
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"SEC",
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"SED",
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"SEI",
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"STA",
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"STX",
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"STY",
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"TAX",
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"TAY",
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"TSX",
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"TXA",
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"TXS",
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"TYA",
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"_END",
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}
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// The OpType consists of a 6502 instruction and addressing mode.
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// It does not include any following operand
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type OpType struct {
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// Opcode is the instruction + addresing mode
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Opcode byte
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// Internal id for the used instruction/mnemonic
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id uint8
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// Internal id for the addressing mode
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addressing uint8
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// Bytes is the size of the instruction and its expected operands.
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// 1 byte: opcode with implicit or null operand
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// 2 bytes: opcode with immediate or zeropage operand (8-bit operand)
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// 3 bytes: opcode with address operands
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Bytes uint8
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// Cycles, number of clock cycles it takes to execute this opcode
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Cycles uint8
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}
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// See http://www.e-tradition.net/bytes/6502/6502_instruction_set.html for details
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var optypes = map[uint8]OpType{
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0x69: OpType{0x69, adc, immediate, 2, 2},
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0x65: OpType{0x69, adc, zeropage, 2, 3},
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0x75: OpType{0x75, adc, zeropageX, 2, 4},
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0x6D: OpType{0x6D, adc, absolute, 3, 4},
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0x7D: OpType{0x7D, adc, absoluteX, 3, 4},
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0x79: OpType{0x79, adc, absoluteY, 3, 4},
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0x61: OpType{0x61, adc, indirectX, 2, 6},
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0x71: OpType{0x71, adc, indirectY, 2, 5},
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0x29: OpType{0x29, and, immediate, 2, 2},
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0x25: OpType{0x25, and, zeropage, 2, 3},
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0x35: OpType{0x35, and, zeropageX, 2, 4},
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0x2D: OpType{0x2D, and, absolute, 3, 4},
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0x3D: OpType{0x3D, and, absoluteX, 3, 4},
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0x39: OpType{0x39, and, absoluteY, 3, 4},
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0x21: OpType{0x21, and, indirectX, 2, 6},
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0x31: OpType{0x31, and, indirectY, 2, 5},
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0x0A: OpType{0x0A, asl, accumulator, 1, 2},
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0x06: OpType{0x06, asl, zeropage, 2, 5},
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0x16: OpType{0x16, asl, zeropageX, 2, 6},
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0x0E: OpType{0x0E, asl, absolute, 3, 6},
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0x1E: OpType{0x1E, asl, absoluteX, 3, 7},
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0x90: OpType{0x90, bcc, relative, 2, 2},
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0xB0: OpType{0xB0, bcs, relative, 2, 2},
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0xF0: OpType{0xF0, beq, relative, 2, 2},
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0x24: OpType{0x24, bit, zeropage, 2, 3},
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0x2C: OpType{0x2C, bit, absolute, 3, 4},
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0x30: OpType{0x30, bmi, relative, 2, 2},
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0xD0: OpType{0xD0, bne, relative, 2, 2},
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0x10: OpType{0x10, bpl, relative, 2, 2},
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0x00: OpType{0x00, brk, implied, 1, 7},
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0x50: OpType{0x50, bvc, relative, 2, 2},
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0x70: OpType{0x70, bvs, relative, 2, 2},
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0x18: OpType{0x18, clc, implied, 1, 2},
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0xD8: OpType{0xD8, cld, implied, 1, 2},
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0x58: OpType{0x58, cli, implied, 1, 2},
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0xB8: OpType{0xB8, clv, implied, 1, 2},
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0xC9: OpType{0xC9, cmp, immediate, 2, 2},
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0xC5: OpType{0xC5, cmp, zeropage, 2, 3},
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0xD5: OpType{0xD5, cmp, zeropageX, 2, 4},
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0xCD: OpType{0xCD, cmp, absolute, 3, 4},
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0xDD: OpType{0xDD, cmp, absoluteX, 3, 4},
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0xD9: OpType{0xD9, cmp, absoluteY, 3, 4},
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0xC1: OpType{0xC1, cmp, indirectX, 2, 6},
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0xD1: OpType{0xD1, cmp, indirectY, 2, 5},
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0xE0: OpType{0xE0, cpx, immediate, 2, 2},
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0xE4: OpType{0xE4, cpx, zeropage, 2, 3},
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0xEC: OpType{0xEC, cpx, absolute, 3, 4},
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0xC0: OpType{0xC0, cpy, immediate, 2, 2},
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0xC4: OpType{0xC4, cpy, zeropage, 2, 3},
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0xCC: OpType{0xCC, cpy, absolute, 3, 4},
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0xC6: OpType{0xC6, dec, zeropage, 2, 5},
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0xD6: OpType{0xD6, dec, zeropageX, 2, 6},
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0xCE: OpType{0xCE, dec, absolute, 3, 3},
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0xDE: OpType{0xDE, dec, absoluteX, 3, 7},
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0xCA: OpType{0xCA, dex, implied, 1, 2},
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0x88: OpType{0x88, dey, implied, 1, 2},
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0x49: OpType{0x49, eor, immediate, 2, 2},
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0x45: OpType{0x45, eor, zeropage, 2, 3},
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0x55: OpType{0x55, eor, zeropageX, 2, 4},
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0x4D: OpType{0x4D, eor, absolute, 3, 4},
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0x5D: OpType{0x5D, eor, absoluteX, 3, 4},
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0x59: OpType{0x59, eor, absoluteY, 3, 4},
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0x41: OpType{0x41, eor, indirectX, 2, 6},
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0x51: OpType{0x51, eor, indirectY, 2, 5},
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0xE6: OpType{0xE6, inc, zeropage, 2, 5},
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0xF6: OpType{0xF6, inc, zeropageX, 2, 6},
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0xEE: OpType{0xEE, inc, absolute, 3, 6},
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0xFE: OpType{0xFE, inc, absoluteX, 3, 7},
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0xE8: OpType{0xE8, inx, implied, 1, 2},
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0xC8: OpType{0xC8, iny, implied, 1, 2},
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0x4C: OpType{0x4C, jmp, absolute, 3, 3},
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0x6C: OpType{0x6C, jmp, indirect, 3, 5},
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0x20: OpType{0x20, jsr, absolute, 3, 6},
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0xA9: OpType{0xA9, lda, immediate, 2, 2},
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0xA5: OpType{0xA5, lda, zeropage, 2, 3},
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0xB5: OpType{0xB5, lda, zeropageX, 2, 4},
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0xAD: OpType{0xAD, lda, absolute, 3, 4},
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0xBD: OpType{0xBD, lda, absoluteX, 3, 4},
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0xB9: OpType{0xB9, lda, absoluteY, 3, 4},
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0xA1: OpType{0xA1, lda, indirectX, 2, 6},
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0xB1: OpType{0xB1, lda, indirectY, 2, 5},
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0xA2: OpType{0xA2, ldx, immediate, 2, 2},
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0xA6: OpType{0xA6, ldx, zeropage, 2, 3},
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0xB6: OpType{0xB6, ldx, zeropageY, 2, 4},
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0xAE: OpType{0xAE, ldx, absolute, 3, 4},
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0xBE: OpType{0xBE, ldx, absoluteY, 3, 4},
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0xA0: OpType{0xA0, ldy, immediate, 2, 2},
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0xA4: OpType{0xA4, ldy, zeropage, 2, 3},
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0xB4: OpType{0xB4, ldy, zeropageX, 2, 4},
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0xAC: OpType{0xAC, ldy, absolute, 3, 4},
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0xBC: OpType{0xBC, ldy, absoluteX, 3, 4},
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0x4A: OpType{0x4A, lsr, accumulator, 1, 2},
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0x46: OpType{0x46, lsr, zeropage, 2, 5},
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0x56: OpType{0x56, lsr, zeropageX, 2, 6},
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0x4E: OpType{0x4E, lsr, absolute, 3, 6},
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0x5E: OpType{0x5E, lsr, absoluteX, 3, 7},
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0xEA: OpType{0xEA, nop, implied, 1, 2},
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0x09: OpType{0x09, ora, immediate, 2, 2},
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0x05: OpType{0x05, ora, zeropage, 2, 3},
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0x15: OpType{0x15, ora, zeropageX, 2, 4},
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0x0D: OpType{0x0D, ora, absolute, 3, 4},
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0x1D: OpType{0x1D, ora, absoluteX, 3, 4},
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0x19: OpType{0x19, ora, absoluteY, 3, 4},
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0x01: OpType{0x01, ora, indirectX, 2, 6},
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0x11: OpType{0x11, ora, indirectY, 2, 5},
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0x48: OpType{0x48, pha, implied, 1, 3},
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0x08: OpType{0x08, php, implied, 1, 3},
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0x68: OpType{0x68, pla, implied, 1, 4},
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0x28: OpType{0x28, php, implied, 1, 4},
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0x2A: OpType{0x2A, rol, accumulator, 1, 2},
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0x26: OpType{0x26, rol, zeropage, 2, 5},
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0x36: OpType{0x36, rol, zeropageX, 2, 6},
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0x2E: OpType{0x2E, rol, absolute, 3, 6},
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0x3E: OpType{0x3E, rol, absoluteX, 3, 7},
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0x6A: OpType{0x6A, ror, accumulator, 1, 2},
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0x66: OpType{0x66, ror, zeropage, 2, 5},
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0x76: OpType{0x76, ror, zeropageX, 2, 6},
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0x6E: OpType{0x6E, ror, absolute, 3, 6},
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0x7E: OpType{0x7E, ror, absoluteX, 3, 7},
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0x40: OpType{0x40, rti, implied, 1, 6},
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0x60: OpType{0x60, rts, implied, 1, 6},
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0xE9: OpType{0xE9, sbc, immediate, 2, 2},
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0xE5: OpType{0xE5, sbc, zeropage, 2, 3},
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0xF5: OpType{0xF5, sbc, zeropageX, 2, 4},
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0xED: OpType{0xED, sbc, absolute, 3, 4},
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0xFD: OpType{0xFD, sbc, absoluteX, 3, 4},
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0xF9: OpType{0xF9, sbc, absoluteY, 3, 4},
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0xE1: OpType{0xE1, sbc, indirectX, 2, 6},
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0xF1: OpType{0xF1, sbc, indirectY, 2, 5},
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0x38: OpType{0x38, sec, implied, 1, 2},
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0xF8: OpType{0xF8, sed, implied, 1, 2},
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0x78: OpType{0x78, sei, implied, 1, 2},
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0x85: OpType{0x85, sta, zeropage, 2, 3},
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0x95: OpType{0x95, sta, zeropageX, 2, 4},
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0x8D: OpType{0x8D, sta, absolute, 3, 4},
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0x9D: OpType{0x9D, sta, absoluteX, 3, 5},
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0x99: OpType{0x99, sta, absoluteY, 3, 5},
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0x81: OpType{0x81, sta, indirectX, 2, 6},
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0x91: OpType{0x91, sta, indirectY, 2, 6},
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0x86: OpType{0x86, stx, zeropage, 2, 3},
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0x96: OpType{0x96, stx, zeropageY, 2, 4},
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0x8E: OpType{0x8E, stx, absolute, 3, 4},
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0x84: OpType{0x84, sty, zeropage, 2, 3},
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0x94: OpType{0x94, sty, zeropageX, 2, 4},
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0x8C: OpType{0x8C, sty, absolute, 3, 4},
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0xAA: OpType{0xAA, tax, implied, 1, 2},
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0xA8: OpType{0xA8, tay, implied, 1, 2},
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0xBA: OpType{0xBA, tsx, implied, 1, 2},
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0x8A: OpType{0x8A, txa, implied, 1, 2},
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0x9A: OpType{0x9A, txs, implied, 1, 2},
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0x98: OpType{0x98, tya, implied, 1, 2},
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0xFF: OpType{0xFF, _end, implied, 1, 1},
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}
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