.nes file format: Java parsing library

File extension

nes

KS implementation details

License: WTFPL

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

Usage

Runtime library

All parsing code for Java generated by Kaitai Struct depends on the Java runtime library. You have to install it before you can parse data.

The Java runtime library is published in the Maven Central Repository. Refer to the artifact page for instructions how to add it into your project with the build tool that you use.

Code

Parse a local file and get structure in memory:

Ines data = Ines.fromFile("path/to/local/file.nes");

Or parse structure from a byte array:

byte[] someArray = new byte[] { ... };
Ines data = new Ines(new ByteBufferKaitaiStream(someArray));

After that, one can get various attributes from the structure by invoking getter methods like:

data.header() // => get header

Java source code to parse .nes file format

Ines.java

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

import io.kaitai.struct.ByteBufferKaitaiStream;
import io.kaitai.struct.KaitaiStruct;
import io.kaitai.struct.KaitaiStream;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.Map;
import java.util.HashMap;


/**
 * @see <a href="https://wiki.nesdev.com/w/index.php/INES">Source</a>
 */
public class Ines extends KaitaiStruct {
    public static Ines fromFile(String fileName) throws IOException {
        return new Ines(new ByteBufferKaitaiStream(fileName));
    }

    public Ines(KaitaiStream _io) {
        this(_io, null, null);
    }

    public Ines(KaitaiStream _io, KaitaiStruct _parent) {
        this(_io, _parent, null);
    }

    public Ines(KaitaiStream _io, KaitaiStruct _parent, Ines _root) {
        super(_io);
        this._parent = _parent;
        this._root = _root == null ? this : _root;
        _read();
    }
    private void _read() {
        this._raw_header = this._io.readBytes(16);
        KaitaiStream _io__raw_header = new ByteBufferKaitaiStream(_raw_header);
        this.header = new Header(_io__raw_header, this, _root);
        if (header().f6().trainer()) {
            this.trainer = this._io.readBytes(512);
        }
        this.prgRom = this._io.readBytes((header().lenPrgRom() * 16384));
        this.chrRom = this._io.readBytes((header().lenChrRom() * 8192));
        if (header().f7().playchoice10()) {
            this.playchoice10 = new Playchoice10(this._io, this, _root);
        }
        if (!(_io().isEof())) {
            this.title = new String(this._io.readBytesFull(), Charset.forName("ASCII"));
        }
    }
    public static class Header extends KaitaiStruct {
        public static Header fromFile(String fileName) throws IOException {
            return new Header(new ByteBufferKaitaiStream(fileName));
        }

        public Header(KaitaiStream _io) {
            this(_io, null, null);
        }

        public Header(KaitaiStream _io, Ines _parent) {
            this(_io, _parent, null);
        }

        public Header(KaitaiStream _io, Ines _parent, Ines _root) {
            super(_io);
            this._parent = _parent;
            this._root = _root;
            _read();
        }
        private void _read() {
            this.magic = this._io.readBytes(4);
            if (!(Arrays.equals(magic(), new byte[] { 78, 69, 83, 26 }))) {
                throw new KaitaiStream.ValidationNotEqualError(new byte[] { 78, 69, 83, 26 }, magic(), _io(), "/types/header/seq/0");
            }
            this.lenPrgRom = this._io.readU1();
            this.lenChrRom = this._io.readU1();
            this._raw_f6 = this._io.readBytes(1);
            KaitaiStream _io__raw_f6 = new ByteBufferKaitaiStream(_raw_f6);
            this.f6 = new F6(_io__raw_f6, this, _root);
            this._raw_f7 = this._io.readBytes(1);
            KaitaiStream _io__raw_f7 = new ByteBufferKaitaiStream(_raw_f7);
            this.f7 = new F7(_io__raw_f7, this, _root);
            this.lenPrgRam = this._io.readU1();
            this._raw_f9 = this._io.readBytes(1);
            KaitaiStream _io__raw_f9 = new ByteBufferKaitaiStream(_raw_f9);
            this.f9 = new F9(_io__raw_f9, this, _root);
            this._raw_f10 = this._io.readBytes(1);
            KaitaiStream _io__raw_f10 = new ByteBufferKaitaiStream(_raw_f10);
            this.f10 = new F10(_io__raw_f10, this, _root);
            this.reserved = this._io.readBytes(5);
            if (!(Arrays.equals(reserved(), new byte[] { 0, 0, 0, 0, 0 }))) {
                throw new KaitaiStream.ValidationNotEqualError(new byte[] { 0, 0, 0, 0, 0 }, reserved(), _io(), "/types/header/seq/8");
            }
        }

        /**
         * @see <a href="https://wiki.nesdev.com/w/index.php/INES#Flags_6">Source</a>
         */
        public static class F6 extends KaitaiStruct {
            public static F6 fromFile(String fileName) throws IOException {
                return new F6(new ByteBufferKaitaiStream(fileName));
            }

            public enum Mirroring {
                HORIZONTAL(0),
                VERTICAL(1);

                private final long id;
                Mirroring(long id) { this.id = id; }
                public long id() { return id; }
                private static final Map<Long, Mirroring> byId = new HashMap<Long, Mirroring>(2);
                static {
                    for (Mirroring e : Mirroring.values())
                        byId.put(e.id(), e);
                }
                public static Mirroring byId(long id) { return byId.get(id); }
            }

            public F6(KaitaiStream _io) {
                this(_io, null, null);
            }

            public F6(KaitaiStream _io, Ines.Header _parent) {
                this(_io, _parent, null);
            }

            public F6(KaitaiStream _io, Ines.Header _parent, Ines _root) {
                super(_io);
                this._parent = _parent;
                this._root = _root;
                _read();
            }
            private void _read() {
                this.lowerMapper = this._io.readBitsIntBe(4);
                this.fourScreen = this._io.readBitsIntBe(1) != 0;
                this.trainer = this._io.readBitsIntBe(1) != 0;
                this.hasBatteryRam = this._io.readBitsIntBe(1) != 0;
                this.mirroring = Mirroring.byId(this._io.readBitsIntBe(1));
            }
            private long lowerMapper;
            private boolean fourScreen;
            private boolean trainer;
            private boolean hasBatteryRam;
            private Mirroring mirroring;
            private Ines _root;
            private Ines.Header _parent;

            /**
             * Lower nibble of mapper number
             */
            public long lowerMapper() { return lowerMapper; }

            /**
             * Ignore mirroring control or above mirroring bit; instead provide four-screen VRAM
             */
            public boolean fourScreen() { return fourScreen; }

            /**
             * 512-byte trainer at $7000-$71FF (stored before PRG data)
             */
            public boolean trainer() { return trainer; }

            /**
             * If on the cartridge contains battery-backed PRG RAM ($6000-7FFF) or other persistent memory
             */
            public boolean hasBatteryRam() { return hasBatteryRam; }

            /**
             * if 0, horizontal arrangement. if 1, vertical arrangement
             */
            public Mirroring mirroring() { return mirroring; }
            public Ines _root() { return _root; }
            public Ines.Header _parent() { return _parent; }
        }

        /**
         * @see <a href="https://wiki.nesdev.com/w/index.php/INES#Flags_7">Source</a>
         */
        public static class F7 extends KaitaiStruct {
            public static F7 fromFile(String fileName) throws IOException {
                return new F7(new ByteBufferKaitaiStream(fileName));
            }

            public F7(KaitaiStream _io) {
                this(_io, null, null);
            }

            public F7(KaitaiStream _io, Ines.Header _parent) {
                this(_io, _parent, null);
            }

            public F7(KaitaiStream _io, Ines.Header _parent, Ines _root) {
                super(_io);
                this._parent = _parent;
                this._root = _root;
                _read();
            }
            private void _read() {
                this.upperMapper = this._io.readBitsIntBe(4);
                this.format = this._io.readBitsIntBe(2);
                this.playchoice10 = this._io.readBitsIntBe(1) != 0;
                this.vsUnisystem = this._io.readBitsIntBe(1) != 0;
            }
            private long upperMapper;
            private long format;
            private boolean playchoice10;
            private boolean vsUnisystem;
            private Ines _root;
            private Ines.Header _parent;

            /**
             * Upper nibble of mapper number
             */
            public long upperMapper() { return upperMapper; }

            /**
             * If equal to 2, flags 8-15 are in NES 2.0 format
             */
            public long format() { return format; }

            /**
             * Determines if it made for a Nintendo PlayChoice-10 or not
             */
            public boolean playchoice10() { return playchoice10; }

            /**
             * Determines if it is made for a Nintendo VS Unisystem or not
             */
            public boolean vsUnisystem() { return vsUnisystem; }
            public Ines _root() { return _root; }
            public Ines.Header _parent() { return _parent; }
        }

        /**
         * @see <a href="https://wiki.nesdev.com/w/index.php/INES#Flags_9">Source</a>
         */
        public static class F9 extends KaitaiStruct {
            public static F9 fromFile(String fileName) throws IOException {
                return new F9(new ByteBufferKaitaiStream(fileName));
            }

            public enum TvSystem {
                NTSC(0),
                PAL(1);

                private final long id;
                TvSystem(long id) { this.id = id; }
                public long id() { return id; }
                private static final Map<Long, TvSystem> byId = new HashMap<Long, TvSystem>(2);
                static {
                    for (TvSystem e : TvSystem.values())
                        byId.put(e.id(), e);
                }
                public static TvSystem byId(long id) { return byId.get(id); }
            }

            public F9(KaitaiStream _io) {
                this(_io, null, null);
            }

            public F9(KaitaiStream _io, Ines.Header _parent) {
                this(_io, _parent, null);
            }

            public F9(KaitaiStream _io, Ines.Header _parent, Ines _root) {
                super(_io);
                this._parent = _parent;
                this._root = _root;
                _read();
            }
            private void _read() {
                this.reserved = this._io.readBitsIntBe(7);
                this.tvSystem = TvSystem.byId(this._io.readBitsIntBe(1));
            }
            private long reserved;
            private TvSystem tvSystem;
            private Ines _root;
            private Ines.Header _parent;
            public long reserved() { return reserved; }

            /**
             * if 0, NTSC. If 1, PAL.
             */
            public TvSystem tvSystem() { return tvSystem; }
            public Ines _root() { return _root; }
            public Ines.Header _parent() { return _parent; }
        }

        /**
         * @see <a href="https://wiki.nesdev.com/w/index.php/INES#Flags_10">Source</a>
         */
        public static class F10 extends KaitaiStruct {
            public static F10 fromFile(String fileName) throws IOException {
                return new F10(new ByteBufferKaitaiStream(fileName));
            }

            public enum TvSystem {
                NTSC(0),
                DUAL1(1),
                PAL(2),
                DUAL2(3);

                private final long id;
                TvSystem(long id) { this.id = id; }
                public long id() { return id; }
                private static final Map<Long, TvSystem> byId = new HashMap<Long, TvSystem>(4);
                static {
                    for (TvSystem e : TvSystem.values())
                        byId.put(e.id(), e);
                }
                public static TvSystem byId(long id) { return byId.get(id); }
            }

            public F10(KaitaiStream _io) {
                this(_io, null, null);
            }

            public F10(KaitaiStream _io, Ines.Header _parent) {
                this(_io, _parent, null);
            }

            public F10(KaitaiStream _io, Ines.Header _parent, Ines _root) {
                super(_io);
                this._parent = _parent;
                this._root = _root;
                _read();
            }
            private void _read() {
                this.reserved1 = this._io.readBitsIntBe(2);
                this.busConflict = this._io.readBitsIntBe(1) != 0;
                this.prgRam = this._io.readBitsIntBe(1) != 0;
                this.reserved2 = this._io.readBitsIntBe(2);
                this.tvSystem = TvSystem.byId(this._io.readBitsIntBe(2));
            }
            private long reserved1;
            private boolean busConflict;
            private boolean prgRam;
            private long reserved2;
            private TvSystem tvSystem;
            private Ines _root;
            private Ines.Header _parent;
            public long reserved1() { return reserved1; }

            /**
             * If 0, no bus conflicts. If 1, bus conflicts.
             */
            public boolean busConflict() { return busConflict; }

            /**
             * If 0, PRG ram is present. If 1, not present.
             */
            public boolean prgRam() { return prgRam; }
            public long reserved2() { return reserved2; }

            /**
             * if 0, NTSC. If 2, PAL. If 1 or 3, dual compatible.
             */
            public TvSystem tvSystem() { return tvSystem; }
            public Ines _root() { return _root; }
            public Ines.Header _parent() { return _parent; }
        }
        private Integer mapper;

        /**
         * @see <a href="https://wiki.nesdev.com/w/index.php/Mapper">Source</a>
         */
        public Integer mapper() {
            if (this.mapper != null)
                return this.mapper;
            int _tmp = (int) ((f6().lowerMapper() | (f7().upperMapper() << 4)));
            this.mapper = _tmp;
            return this.mapper;
        }
        private byte[] magic;
        private int lenPrgRom;
        private int lenChrRom;
        private F6 f6;
        private F7 f7;
        private int lenPrgRam;
        private F9 f9;
        private F10 f10;
        private byte[] reserved;
        private Ines _root;
        private Ines _parent;
        private byte[] _raw_f6;
        private byte[] _raw_f7;
        private byte[] _raw_f9;
        private byte[] _raw_f10;
        public byte[] magic() { return magic; }

        /**
         * Size of PRG ROM in 16 KB units
         */
        public int lenPrgRom() { return lenPrgRom; }

        /**
         * Size of CHR ROM in 8 KB units (Value 0 means the board uses CHR RAM)
         */
        public int lenChrRom() { return lenChrRom; }
        public F6 f6() { return f6; }
        public F7 f7() { return f7; }

        /**
         * Size of PRG RAM in 8 KB units (Value 0 infers 8 KB for compatibility; see PRG RAM circuit on nesdev.com)
         */
        public int lenPrgRam() { return lenPrgRam; }
        public F9 f9() { return f9; }

        /**
         * this one is unofficial
         */
        public F10 f10() { return f10; }
        public byte[] reserved() { return reserved; }
        public Ines _root() { return _root; }
        public Ines _parent() { return _parent; }
        public byte[] _raw_f6() { return _raw_f6; }
        public byte[] _raw_f7() { return _raw_f7; }
        public byte[] _raw_f9() { return _raw_f9; }
        public byte[] _raw_f10() { return _raw_f10; }
    }

    /**
     * @see <a href="http://wiki.nesdev.com/w/index.php/PC10_ROM-Images">Source</a>
     */
    public static class Playchoice10 extends KaitaiStruct {
        public static Playchoice10 fromFile(String fileName) throws IOException {
            return new Playchoice10(new ByteBufferKaitaiStream(fileName));
        }

        public Playchoice10(KaitaiStream _io) {
            this(_io, null, null);
        }

        public Playchoice10(KaitaiStream _io, Ines _parent) {
            this(_io, _parent, null);
        }

        public Playchoice10(KaitaiStream _io, Ines _parent, Ines _root) {
            super(_io);
            this._parent = _parent;
            this._root = _root;
            _read();
        }
        private void _read() {
            this.instRom = this._io.readBytes(8192);
            this.prom = new Prom(this._io, this, _root);
        }
        public static class Prom extends KaitaiStruct {
            public static Prom fromFile(String fileName) throws IOException {
                return new Prom(new ByteBufferKaitaiStream(fileName));
            }

            public Prom(KaitaiStream _io) {
                this(_io, null, null);
            }

            public Prom(KaitaiStream _io, Ines.Playchoice10 _parent) {
                this(_io, _parent, null);
            }

            public Prom(KaitaiStream _io, Ines.Playchoice10 _parent, Ines _root) {
                super(_io);
                this._parent = _parent;
                this._root = _root;
                _read();
            }
            private void _read() {
                this.data = this._io.readBytes(16);
                this.counterOut = this._io.readBytes(16);
            }
            private byte[] data;
            private byte[] counterOut;
            private Ines _root;
            private Ines.Playchoice10 _parent;
            public byte[] data() { return data; }
            public byte[] counterOut() { return counterOut; }
            public Ines _root() { return _root; }
            public Ines.Playchoice10 _parent() { return _parent; }
        }
        private byte[] instRom;
        private Prom prom;
        private Ines _root;
        private Ines _parent;
        public byte[] instRom() { return instRom; }
        public Prom prom() { return prom; }
        public Ines _root() { return _root; }
        public Ines _parent() { return _parent; }
    }
    private Header header;
    private byte[] trainer;
    private byte[] prgRom;
    private byte[] chrRom;
    private Playchoice10 playchoice10;
    private String title;
    private Ines _root;
    private KaitaiStruct _parent;
    private byte[] _raw_header;
    public Header header() { return header; }
    public byte[] trainer() { return trainer; }
    public byte[] prgRom() { return prgRom; }
    public byte[] chrRom() { return chrRom; }
    public Playchoice10 playchoice10() { return playchoice10; }
    public String title() { return title; }
    public Ines _root() { return _root; }
    public KaitaiStruct _parent() { return _parent; }
    public byte[] _raw_header() { return _raw_header; }
}