code_6502: JavaScript parsing library

This spec can be used to disassemble raw stream of 6502 CPU machine code into individual operations. Each operation includes an opcode and, optionally, an argument. Register arguments are part of the opcode enum.

KS implementation details

License: CC0-1.0

This page hosts a formal specification of code_6502 using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

JavaScript source code to parse code_6502

Code6502.js

// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

/**
 * This spec can be used to disassemble raw stream of 6502 CPU machine
 * code into individual operations. Each operation includes an opcode
 * and, optionally, an argument. Register arguments are part of the
 * `opcode` enum.
 */

var Code6502 = (function() {
  Code6502.Opcode = Object.freeze({
    BRK_IMPL: 0,
    ORA_X_IND: 1,
    ORA_ZPG: 5,
    ASL_ZPG: 6,
    PHP_IMPL: 8,
    ORA_IMM: 9,
    ASL_A: 10,
    ORA_ABS: 13,
    ASL_ABS: 14,
    BPL_REL: 16,
    ORA_IND_Y: 17,
    ORA_ZPG_X: 21,
    ASL_ZPG_X: 22,
    CLC_IMPL: 24,
    ORA_ABS_Y: 25,
    ORA_ABS_X: 29,
    ASL_ABS_X: 30,
    JSR_ABS: 32,
    AND_X_IND: 33,
    BIT_ZPG: 36,
    AND_ZPG: 37,
    ROL_ZPG: 38,
    PLP_IMPL: 40,
    AND_IMM: 41,
    ROL_A: 42,
    BIT_ABS: 44,
    AND_ABS: 45,
    ROL_ABS: 46,
    BMI_REL: 48,
    AND_IND_Y: 49,
    AND_ZPG_X: 53,
    ROL_ZPG_X: 54,
    SEC_IMPL: 56,
    AND_ABS_Y: 57,
    AND_ABS_X: 61,
    ROL_ABS_X: 62,
    RTI_IMPL: 64,
    EOR_X_IND: 65,
    EOR_ZPG: 69,
    LSR_ZPG: 70,
    PHA_IMPL: 72,
    EOR_IMM: 73,
    LSR_A: 74,
    JMP_ABS: 76,
    EOR_ABS: 77,
    LSR_ABS: 78,
    BVC_REL: 80,
    EOR_IND_Y: 81,
    EOR_ZPG_X: 85,
    LSR_ZPG_X: 86,
    CLI_IMPL: 88,
    EOR_ABS_Y: 89,
    EOR_ABS_X: 93,
    LSR_ABS_X: 94,
    RTS_IMPL: 96,
    ADC_X_IND: 97,
    ADC_ZPG: 101,
    ROR_ZPG: 102,
    PLA_IMPL: 104,
    ADC_IMM: 105,
    ROR_A: 106,
    JMP_IND: 108,
    ADC_ABS: 109,
    ROR_ABS: 110,
    BVS_REL: 112,
    ADC_IND_Y: 113,
    ADC_ZPG_X: 117,
    ROR_ZPG_X: 118,
    SEI_IMPL: 120,
    ADC_ABS_Y: 121,
    ADC_ABS_X: 125,
    ROR_ABS_X: 126,
    STA_X_IND: 129,
    STY_ZPG: 132,
    STA_ZPG: 133,
    STX_ZPG: 134,
    DEY_IMPL: 136,
    TXA_IMPL: 138,
    STY_ABS: 140,
    STA_ABS: 141,
    STX_ABS: 142,
    BCC_REL: 144,
    STA_IND_Y: 145,
    STY_ZPG_X: 148,
    STA_ZPG_X: 149,
    STX_ZPG_Y: 150,
    TYA_IMPL: 152,
    STA_ABS_Y: 153,
    TXS_IMPL: 154,
    STA_ABS_X: 157,
    LDY_IMM: 160,
    LDA_X_IND: 161,
    LDX_IMM: 162,
    LDY_ZPG: 164,
    LDA_ZPG: 165,
    LDX_ZPG: 166,
    TAY_IMPL: 168,
    LDA_IMM: 169,
    TAX_IMPL: 170,
    LDY_ABS: 172,
    LDA_ABS: 173,
    LDX_ABS: 174,
    BCS_REL: 176,
    LDA_IND_Y: 177,
    LDY_ZPG_X: 180,
    LDA_ZPG_X: 181,
    LDX_ZPG_Y: 182,
    CLV_IMPL: 184,
    LDA_ABS_Y: 185,
    TSX_IMPL: 186,
    LDY_ABS_X: 188,
    LDA_ABS_X: 189,
    LDX_ABS_Y: 190,
    CPY_IMM: 192,
    CMP_X_IND: 193,
    CPY_ZPG: 196,
    CMP_ZPG: 197,
    DEC_ZPG: 198,
    INY_IMPL: 200,
    CMP_IMM: 201,
    DEX_IMPL: 202,
    CPY_ABS: 204,
    CMP_ABS: 205,
    DEC_ABS: 206,
    BNE_REL: 208,
    CMP_IND_Y: 209,
    CMP_ZPG_X: 213,
    DEC_ZPG_X: 214,
    CLD_IMPL: 216,
    CMP_ABS_Y: 217,
    CMP_ABS_X: 221,
    DEC_ABS_X: 222,
    CPX_IMM: 224,
    SBC_X_IND: 225,
    CPX_ZPG: 228,
    SBC_ZPG: 229,
    INC_ZPG: 230,
    INX_IMPL: 232,
    SBC_IMM: 233,
    NOP_IMPL: 234,
    CPX_ABS: 236,
    SBC_ABS: 237,
    INC_ABS: 238,
    BEQ_REL: 240,
    SBC_IND_Y: 241,
    SBC_ZPG_X: 245,
    INC_ZPG_X: 246,
    SED_IMPL: 248,
    SBC_ABS_Y: 249,
    SBC_ABS_X: 253,
    INC_ABS_X: 254,

    0: "BRK_IMPL",
    1: "ORA_X_IND",
    5: "ORA_ZPG",
    6: "ASL_ZPG",
    8: "PHP_IMPL",
    9: "ORA_IMM",
    10: "ASL_A",
    13: "ORA_ABS",
    14: "ASL_ABS",
    16: "BPL_REL",
    17: "ORA_IND_Y",
    21: "ORA_ZPG_X",
    22: "ASL_ZPG_X",
    24: "CLC_IMPL",
    25: "ORA_ABS_Y",
    29: "ORA_ABS_X",
    30: "ASL_ABS_X",
    32: "JSR_ABS",
    33: "AND_X_IND",
    36: "BIT_ZPG",
    37: "AND_ZPG",
    38: "ROL_ZPG",
    40: "PLP_IMPL",
    41: "AND_IMM",
    42: "ROL_A",
    44: "BIT_ABS",
    45: "AND_ABS",
    46: "ROL_ABS",
    48: "BMI_REL",
    49: "AND_IND_Y",
    53: "AND_ZPG_X",
    54: "ROL_ZPG_X",
    56: "SEC_IMPL",
    57: "AND_ABS_Y",
    61: "AND_ABS_X",
    62: "ROL_ABS_X",
    64: "RTI_IMPL",
    65: "EOR_X_IND",
    69: "EOR_ZPG",
    70: "LSR_ZPG",
    72: "PHA_IMPL",
    73: "EOR_IMM",
    74: "LSR_A",
    76: "JMP_ABS",
    77: "EOR_ABS",
    78: "LSR_ABS",
    80: "BVC_REL",
    81: "EOR_IND_Y",
    85: "EOR_ZPG_X",
    86: "LSR_ZPG_X",
    88: "CLI_IMPL",
    89: "EOR_ABS_Y",
    93: "EOR_ABS_X",
    94: "LSR_ABS_X",
    96: "RTS_IMPL",
    97: "ADC_X_IND",
    101: "ADC_ZPG",
    102: "ROR_ZPG",
    104: "PLA_IMPL",
    105: "ADC_IMM",
    106: "ROR_A",
    108: "JMP_IND",
    109: "ADC_ABS",
    110: "ROR_ABS",
    112: "BVS_REL",
    113: "ADC_IND_Y",
    117: "ADC_ZPG_X",
    118: "ROR_ZPG_X",
    120: "SEI_IMPL",
    121: "ADC_ABS_Y",
    125: "ADC_ABS_X",
    126: "ROR_ABS_X",
    129: "STA_X_IND",
    132: "STY_ZPG",
    133: "STA_ZPG",
    134: "STX_ZPG",
    136: "DEY_IMPL",
    138: "TXA_IMPL",
    140: "STY_ABS",
    141: "STA_ABS",
    142: "STX_ABS",
    144: "BCC_REL",
    145: "STA_IND_Y",
    148: "STY_ZPG_X",
    149: "STA_ZPG_X",
    150: "STX_ZPG_Y",
    152: "TYA_IMPL",
    153: "STA_ABS_Y",
    154: "TXS_IMPL",
    157: "STA_ABS_X",
    160: "LDY_IMM",
    161: "LDA_X_IND",
    162: "LDX_IMM",
    164: "LDY_ZPG",
    165: "LDA_ZPG",
    166: "LDX_ZPG",
    168: "TAY_IMPL",
    169: "LDA_IMM",
    170: "TAX_IMPL",
    172: "LDY_ABS",
    173: "LDA_ABS",
    174: "LDX_ABS",
    176: "BCS_REL",
    177: "LDA_IND_Y",
    180: "LDY_ZPG_X",
    181: "LDA_ZPG_X",
    182: "LDX_ZPG_Y",
    184: "CLV_IMPL",
    185: "LDA_ABS_Y",
    186: "TSX_IMPL",
    188: "LDY_ABS_X",
    189: "LDA_ABS_X",
    190: "LDX_ABS_Y",
    192: "CPY_IMM",
    193: "CMP_X_IND",
    196: "CPY_ZPG",
    197: "CMP_ZPG",
    198: "DEC_ZPG",
    200: "INY_IMPL",
    201: "CMP_IMM",
    202: "DEX_IMPL",
    204: "CPY_ABS",
    205: "CMP_ABS",
    206: "DEC_ABS",
    208: "BNE_REL",
    209: "CMP_IND_Y",
    213: "CMP_ZPG_X",
    214: "DEC_ZPG_X",
    216: "CLD_IMPL",
    217: "CMP_ABS_Y",
    221: "CMP_ABS_X",
    222: "DEC_ABS_X",
    224: "CPX_IMM",
    225: "SBC_X_IND",
    228: "CPX_ZPG",
    229: "SBC_ZPG",
    230: "INC_ZPG",
    232: "INX_IMPL",
    233: "SBC_IMM",
    234: "NOP_IMPL",
    236: "CPX_ABS",
    237: "SBC_ABS",
    238: "INC_ABS",
    240: "BEQ_REL",
    241: "SBC_IND_Y",
    245: "SBC_ZPG_X",
    246: "INC_ZPG_X",
    248: "SED_IMPL",
    249: "SBC_ABS_Y",
    253: "SBC_ABS_X",
    254: "INC_ABS_X",
  });

  function Code6502(_io, _parent, _root) {
    this._io = _io;
    this._parent = _parent;
    this._root = _root || this;

    this._read();
  }
  Code6502.prototype._read = function() {
    this.operations = [];
    var i = 0;
    while (!this._io.isEof()) {
      this.operations.push(new Operation(this._io, this, this._root));
      i++;
    }
  }

  var Operation = Code6502.Operation = (function() {
    function Operation(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    Operation.prototype._read = function() {
      this.code = this._io.readU1();
      switch (this.code) {
      case Code6502.Opcode.LSR_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.AND_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.BIT_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ASL_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ROR_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.STY_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ORA_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.EOR_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.EOR_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.EOR_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ORA_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ADC_ABS_Y:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.STY_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.EOR_IND_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ROL_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.EOR_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.BMI_REL:
        this.args = this._io.readS1();
        break;
      case Code6502.Opcode.INC_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.CPY_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.JSR_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.AND_ABS_Y:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.CMP_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.SBC_IND_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.AND_X_IND:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.BVC_REL:
        this.args = this._io.readS1();
        break;
      case Code6502.Opcode.ORA_X_IND:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ORA_ABS_Y:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.LSR_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.LDX_ZPG_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ROL_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ADC_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.STY_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ORA_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDY_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ADC_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.SBC_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDX_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.BEQ_REL:
        this.args = this._io.readS1();
        break;
      case Code6502.Opcode.SBC_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.LDX_ABS_Y:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ORA_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.BCS_REL:
        this.args = this._io.readS1();
        break;
      case Code6502.Opcode.SBC_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.STA_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.BCC_REL:
        this.args = this._io.readS1();
        break;
      case Code6502.Opcode.AND_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDY_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ADC_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.BNE_REL:
        this.args = this._io.readS1();
        break;
      case Code6502.Opcode.EOR_ABS_Y:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.CPY_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.STX_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.LDY_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDA_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.CMP_ABS_Y:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.LSR_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.EOR_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.CMP_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.INC_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.STA_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.STA_X_IND:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.CMP_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.EOR_X_IND:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.CMP_IND_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.CMP_X_IND:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ASL_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.DEC_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.SBC_ABS_Y:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.STX_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDA_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.AND_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.SBC_X_IND:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDA_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.JMP_IND:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.STA_ABS_Y:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ASL_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.CMP_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDX_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ADC_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ROR_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.AND_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.STA_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ADC_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.BIT_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.DEC_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.STX_ZPG_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDA_ABS_Y:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.LDA_X_IND:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.CPY_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ORA_IND_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ASL_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.AND_IND_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.STA_IND_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ROR_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.LDX_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.AND_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.CPX_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.BVS_REL:
        this.args = this._io.readS1();
        break;
      case Code6502.Opcode.LDY_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.INC_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.SBC_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ROL_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.SBC_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ADC_X_IND:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.STA_ABS_X:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.CPX_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.CMP_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.LDA_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ROL_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.INC_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDA_IMM:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.DEC_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.ADC_IND_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDA_IND_Y:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.BPL_REL:
        this.args = this._io.readS1();
        break;
      case Code6502.Opcode.LSR_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.JMP_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.DEC_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ORA_ABS:
        this.args = this._io.readU2le();
        break;
      case Code6502.Opcode.ROR_ZPG:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.LDY_ZPG_X:
        this.args = this._io.readU1();
        break;
      case Code6502.Opcode.CPX_ZPG:
        this.args = this._io.readU1();
        break;
      }
    }

    return Operation;
  })();

  return Code6502;
})();

// Export for amd environments
if (typeof define === 'function' && define.amd) {
  define('Code6502', [], function() {
    return Code6502;
  });
}

// Export for CommonJS
if (typeof module === 'object' && module && module.exports) {
  module.exports = Code6502;
}