/** * Pure-JS implementation of WebTV's LZPF compression * * This is a port of my Lzpf compression code from my ROMFS Python tool * Originally reverse engineered from the box * * By: Eric MacDonald (eMac) */ class WTVLzpf { // Note: currentlty doesn't offer streaming support but this is good enough to meet perf demands at the scale we're at. current_length = 0 current_literal = 0 flag_table = new Uint16Array(0x1000) compressed_data = [] nomatchEncode = [ [0x0000, 0x10], [0x0001, 0x10], [0x0002, 0x10], [0x0003, 0x10], [0x0004, 0x10], [0x009A, 0x0F], [0x0005, 0x10], [0x009C, 0x0F], [0x009E, 0x0F], [0x3400, 0x06], [0x7000, 0x05], [0x00A0, 0x0F], [0x0006, 0x10], [0x0380, 0x09], [0x0007, 0x10], [0x0008, 0x10], [0x0009, 0x10], [0x000A, 0x10], [0x000B, 0x10], [0x000C, 0x10], [0x000D, 0x10], [0x000E, 0x10], [0x000F, 0x10], [0x00A2, 0x0F], [0x0010, 0x10], [0x0011, 0x10], [0x0012, 0x10], [0x0013, 0x10], [0x0014, 0x10], [0x0015, 0x10], [0x0016, 0x10], [0x0017, 0x10], [0xE000, 0x04], [0x0200, 0x0A], [0x7800, 0x05], [0x0400, 0x09], [0x00B0, 0x0E], [0x0018, 0x10], [0x0120, 0x0B], [0x0480, 0x09], [0x0140, 0x0B], [0x0160, 0x0B], [0x0240, 0x0A], [0x00B8, 0x0D], [0x1400, 0x07], [0x1600, 0x07], [0x3800, 0x06], [0x8000, 0x05], [0x0A00, 0x08], [0x1800, 0x07], [0x0B00, 0x08], [0x0500, 0x09], [0x0C00, 0x08], [0x0580, 0x09], [0x0600, 0x09], [0x0680, 0x09], [0x0700, 0x09], [0x0780, 0x09], [0x0D00, 0x08], [0x0180, 0x0B], [0x8800, 0x05], [0x3C00, 0x06], [0x9000, 0x05], [0x0280, 0x0A], [0x00B4, 0x0E], [0x4000, 0x06], [0x1A00, 0x07], [0x1C00, 0x07], [0x1E00, 0x07], [0x4400, 0x06], [0x2000, 0x07], [0x2200, 0x07], [0x2400, 0x07], [0x4800, 0x06], [0x01A0, 0x0B], [0x02C0, 0x0A], [0x2600, 0x07], [0x0E00, 0x08], [0x4C00, 0x06], [0x5000, 0x06], [0x2800, 0x07], [0x00C0, 0x0C], [0x5400, 0x06], [0x2A00, 0x07], [0x9800, 0x05], [0x0800, 0x09], [0x0880, 0x09], [0x0F00, 0x08], [0x00D0, 0x0C], [0x0300, 0x0A], [0x0900, 0x09], [0x0019, 0x10], [0x001A, 0x10], [0x001B, 0x10], [0x001C, 0x10], [0x1000, 0x08], [0x001D, 0x10], [0xA000, 0x05], [0x2C00, 0x07], [0x5800, 0x06], [0x5C00, 0x06], [0xF000, 0x04], [0x2E00, 0x07], [0x3000, 0x07], [0x6000, 0x06], [0xA800, 0x05], [0x01C0, 0x0B], [0x1100, 0x08], [0x6400, 0x06], [0x6800, 0x06], [0xB000, 0x05], [0xB800, 0x05], [0xC000, 0x05], [0x01E0, 0x0B], [0xC800, 0x05], [0xD000, 0x05], [0xD800, 0x05], [0x3200, 0x07], [0x1200, 0x08], [0x6C00, 0x06], [0x0980, 0x09], [0x1300, 0x08], [0x0340, 0x0A], [0x00E0, 0x0C], [0x00F0, 0x0C], [0x0100, 0x0C], [0x0110, 0x0C], [0x001E, 0x10], [0x001F, 0x10], [0x0020, 0x10], [0x0021, 0x10], [0x0022, 0x10], [0x0023, 0x10], [0x0024, 0x10], [0x0025, 0x10], [0x0026, 0x10], [0x0027, 0x10], [0x0028, 0x10], [0x0029, 0x10], [0x002A, 0x10], [0x002B, 0x10], [0x002C, 0x10], [0x002D, 0x10], [0x002E, 0x10], [0x002F, 0x10], [0x00A4, 0x0F], [0x00A6, 0x0F], [0x00A8, 0x0F], [0x0030, 0x10], [0x0031, 0x10], [0x0032, 0x10], [0x0033, 0x10], [0x0034, 0x10], [0x0035, 0x10], [0x0036, 0x10], [0x0037, 0x10], [0x0038, 0x10], [0x0039, 0x10], [0x003A, 0x10], [0x003B, 0x10], [0x003C, 0x10], [0x003D, 0x10], [0x003E, 0x10], [0x003F, 0x10], [0x0040, 0x10], [0x0041, 0x10], [0x0042, 0x10], [0x0043, 0x10], [0x0044, 0x10], [0x0045, 0x10], [0x0046, 0x10], [0x0047, 0x10], [0x0048, 0x10], [0x0049, 0x10], [0x004A, 0x10], [0x004B, 0x10], [0x004C, 0x10], [0x004D, 0x10], [0x004E, 0x10], [0x004F, 0x10], [0x0050, 0x10], [0x0051, 0x10], [0x0052, 0x10], [0x0053, 0x10], [0x0054, 0x10], [0x0055, 0x10], [0x0056, 0x10], [0x0057, 0x10], [0x0058, 0x10], [0x0059, 0x10], [0x005A, 0x10], [0x005B, 0x10], [0x005C, 0x10], [0x005D, 0x10], [0x005E, 0x10], [0x005F, 0x10], [0x0060, 0x10], [0x0061, 0x10], [0x0062, 0x10], [0x00AA, 0x0F], [0x0063, 0x10], [0x0064, 0x10], [0x0065, 0x10], [0x0066, 0x10], [0x0067, 0x10], [0x0068, 0x10], [0x0069, 0x10], [0x006A, 0x10], [0x006B, 0x10], [0x006C, 0x10], [0x006D, 0x10], [0x006E, 0x10], [0x006F, 0x10], [0x0070, 0x10], [0x0071, 0x10], [0x0072, 0x10], [0x0073, 0x10], [0x0074, 0x10], [0x0075, 0x10], [0x0076, 0x10], [0x0077, 0x10], [0x0078, 0x10], [0x0079, 0x10], [0x007A, 0x10], [0x007B, 0x10], [0x007C, 0x10], [0x007D, 0x10], [0x007E, 0x10], [0x007F, 0x10], [0x0080, 0x10], [0x0081, 0x10], [0x0082, 0x10], [0x0083, 0x10], [0x0084, 0x10], [0x0085, 0x10], [0x0086, 0x10], [0x0087, 0x10], [0x0088, 0x10], [0x0089, 0x10], [0x008A, 0x10], [0x008B, 0x10], [0x008C, 0x10], [0x008D, 0x10], [0x00AC, 0x0F], [0x008E, 0x10], [0x008F, 0x10], [0x0090, 0x10], [0x0091, 0x10], [0x0092, 0x10], [0x0093, 0x10], [0x00AE, 0x0F], [0x0094, 0x10], [0x0095, 0x10], [0x0096, 0x10], [0x0097, 0x10], [0x0098, 0x10], [0x0099, 0x10] ]; matchEncode = [ [0x80000000, 0x01], [0x80000000, 0x03], [0xA0000000, 0x03], [0xC0000000, 0x03], [0xE0000000, 0x06], [0xE4000000, 0x06], [0xE8000000, 0x06], [0xEC000000, 0x06], [0xF0000000, 0x06], [0xF4000000, 0x06], [0xF8000000, 0x06], [0xFC000000, 0x0B], [0xFC200000, 0x0B], [0xFC400000, 0x0B], [0xFC600000, 0x0B], [0xFC800000, 0x0B], [0xFCA00000, 0x0B], [0xFCC00000, 0x0B], [0xFCE00000, 0x0B], [0xFD000000, 0x0B], [0xFD200000, 0x0B], [0xFD400000, 0x0B], [0xFD600000, 0x0B], [0xFD800000, 0x0B], [0xFDA00000, 0x0B], [0xFDC00000, 0x0B], [0xFDE00000, 0x0B], [0xFE000000, 0x0B], [0xFE200000, 0x0B], [0xFE400000, 0x0B], [0xFE600000, 0x0B], [0xFE800000, 0x0B], [0xFEA00000, 0x0B], [0xFEC00000, 0x0B], [0xFEE00000, 0x0B], [0xFF000000, 0x0B], [0xFF200000, 0x0B], [0xFF400000, 0x0B], [0xFF600000, 0x0B], [0xFF800000, 0x0B], [0xFFA00000, 0x0B], [0xFFC00000, 0x0B], [0xFFE00000, 0x13], [0xFFE02000, 0x13], [0xFFE04000, 0x13], [0xFFE06000, 0x13], [0xFFE08000, 0x13], [0xFFE0A000, 0x13], [0xFFE0C000, 0x13], [0xFFE0E000, 0x13], [0xFFE10000, 0x13], [0xFFE12000, 0x13], [0xFFE14000, 0x13], [0xFFE16000, 0x13], [0xFFE18000, 0x13], [0xFFE1A000, 0x13], [0xFFE1C000, 0x13], [0xFFE1E000, 0x13], [0xFFE20000, 0x13], [0xFFE22000, 0x13], [0xFFE24000, 0x13], [0xFFE26000, 0x13], [0xFFE28000, 0x13], [0xFFE2A000, 0x13], [0xFFE2C000, 0x13], [0xFFE2E000, 0x13], [0xFFE30000, 0x13], [0xFFE32000, 0x13], [0xFFE34000, 0x13], [0xFFE36000, 0x13], [0xFFE38000, 0x13], [0xFFE3A000, 0x13], [0xFFE3C000, 0x13], [0xFFE3E000, 0x13], [0xFFE40000, 0x13], [0xFFE42000, 0x13], [0xFFE44000, 0x13], [0xFFE46000, 0x13], [0xFFE48000, 0x13], [0xFFE4A000, 0x13], [0xFFE4C000, 0x13], [0xFFE4E000, 0x13], [0xFFE50000, 0x13], [0xFFE52000, 0x13], [0xFFE54000, 0x13], [0xFFE56000, 0x13], [0xFFE58000, 0x13], [0xFFE5A000, 0x13], [0xFFE5C000, 0x13], [0xFFE5E000, 0x13], [0xFFE60000, 0x13], [0xFFE62000, 0x13], [0xFFE64000, 0x13], [0xFFE66000, 0x13], [0xFFE68000, 0x13], [0xFFE6A000, 0x13], [0xFFE6C000, 0x13], [0xFFE6E000, 0x13], [0xFFE70000, 0x13], [0xFFE72000, 0x13], [0xFFE74000, 0x13], [0xFFE76000, 0x13], [0xFFE78000, 0x13], [0xFFE7A000, 0x13], [0xFFE7C000, 0x13], [0xFFE7E000, 0x13], [0xFFE80000, 0x13], [0xFFE82000, 0x13], [0xFFE84000, 0x13], [0xFFE86000, 0x13], [0xFFE88000, 0x13], [0xFFE8A000, 0x13], [0xFFE8C000, 0x13], [0xFFE8E000, 0x13], [0xFFE90000, 0x13], [0xFFE92000, 0x13], [0xFFE94000, 0x13], [0xFFE96000, 0x13], [0xFFE98000, 0x13], [0xFFE9A000, 0x13], [0xFFE9C000, 0x13], [0xFFE9E000, 0x13], [0xFFEA0000, 0x13], [0xFFEA2000, 0x13], [0xFFEA4000, 0x13], [0xFFEA6000, 0x13], [0xFFEA8000, 0x13], [0xFFEAA000, 0x13], [0xFFEAC000, 0x13], [0xFFEAE000, 0x13], [0xFFEB0000, 0x13], [0xFFEB2000, 0x13], [0xFFEB4000, 0x13], [0xFFEB6000, 0x13], [0xFFEB8000, 0x13], [0xFFEBA000, 0x13], [0xFFEBC000, 0x13], [0xFFEBE000, 0x13], [0xFFEC0000, 0x13], [0xFFEC2000, 0x13], [0xFFEC4000, 0x13], [0xFFEC6000, 0x13], [0xFFEC8000, 0x13], [0xFFECA000, 0x13], [0xFFECC000, 0x13], [0xFFECE000, 0x13], [0xFFED0000, 0x13], [0xFFED2000, 0x13], [0xFFED4000, 0x13], [0xFFED6000, 0x13], [0xFFED8000, 0x13], [0xFFEDA000, 0x13], [0xFFEDC000, 0x13], [0xFFEDE000, 0x13], [0xFFEE0000, 0x13], [0xFFEE2000, 0x13], [0xFFEE4000, 0x13], [0xFFEE6000, 0x13], [0xFFEE8000, 0x13], [0xFFEEA000, 0x13], [0xFFEEC000, 0x13], [0xFFEEE000, 0x13], [0xFFEF0000, 0x13], [0xFFEF2000, 0x13], [0xFFEF4000, 0x13], [0xFFEF6000, 0x13], [0xFFEF8000, 0x13], [0xFFEFA000, 0x13], [0xFFEFC000, 0x13], [0xFFEFE000, 0x13], [0xFFF00000, 0x13], [0xFFF02000, 0x13], [0xFFF04000, 0x13], [0xFFF06000, 0x13], [0xFFF08000, 0x13], [0xFFF0A000, 0x13], [0xFFF0C000, 0x13], [0xFFF0E000, 0x13], [0xFFF10000, 0x13], [0xFFF12000, 0x13], [0xFFF14000, 0x13], [0xFFF16000, 0x13], [0xFFF18000, 0x13], [0xFFF1A000, 0x13], [0xFFF1C000, 0x13], [0xFFF1E000, 0x13], [0xFFF20000, 0x13], [0xFFF22000, 0x13], [0xFFF24000, 0x13], [0xFFF26000, 0x13], [0xFFF28000, 0x13], [0xFFF2A000, 0x13], [0xFFF2C000, 0x13], [0xFFF2E000, 0x13], [0xFFF30000, 0x13], [0xFFF32000, 0x13], [0xFFF34000, 0x13], [0xFFF36000, 0x13], [0xFFF38000, 0x13], [0xFFF3A000, 0x13], [0xFFF3C000, 0x13], [0xFFF3E000, 0x13], [0xFFF40000, 0x13], [0xFFF42000, 0x13], [0xFFF44000, 0x13], [0xFFF46000, 0x13], [0xFFF48000, 0x13], [0xFFF4A000, 0x13], [0xFFF4C000, 0x13], [0xFFF4E000, 0x13], [0xFFF50000, 0x13], [0xFFF52000, 0x13], [0xFFF54000, 0x13], [0xFFF56000, 0x13], [0xFFF58000, 0x13], [0xFFF5A000, 0x13], [0xFFF5C000, 0x13], [0xFFF5E000, 0x13], [0xFFF60000, 0x13], [0xFFF62000, 0x13], [0xFFF64000, 0x13], [0xFFF66000, 0x13], [0xFFF68000, 0x13], [0xFFF6A000, 0x13], [0xFFF6C000, 0x13], [0xFFF6E000, 0x13], [0xFFF70000, 0x13], [0xFFF72000, 0x13], [0xFFF74000, 0x13], [0xFFF76000, 0x13], [0xFFF78000, 0x13], [0xFFF7A000, 0x13], [0xFFF7C000, 0x13], [0xFFF7E000, 0x13], [0xFFF80000, 0x13], [0xFFF82000, 0x13], [0xFFF84000, 0x13], [0xFFF86000, 0x13], [0xFFF88000, 0x13], [0xFFF8A000, 0x13], [0xFFF8C000, 0x13], [0xFFF8E000, 0x13], [0xFFF90000, 0x13], [0xFFF92000, 0x13], [0xFFF94000, 0x13], [0xFFF96000, 0x13], [0xFFF98000, 0x13], [0xFFF9A000, 0x13], [0xFFF9C000, 0x13], [0xFFF9E000, 0x13], [0xFFFA0000, 0x13], [0xFFFA2000, 0x13], [0xFFFA4000, 0x13], [0xFFFA6000, 0x13], [0xFFFA8000, 0x13], [0xFFFAA000, 0x13], [0xFFFAC000, 0x13], [0xFFFAE000, 0x13], [0xFFFB0000, 0x13], [0xFFFB2000, 0x13], [0xFFFB4000, 0x13], [0xFFFB6000, 0x13], [0xFFFB8000, 0x13], [0xFFFBA000, 0x13], [0xFFFBC000, 0x13], [0xFFFBE000, 0x13], [0xFFFC0000, 0x13], [0xFFFC2000, 0x13], [0xFFFC4000, 0x13], [0xFFFC6000, 0x13], [0xFFFC8000, 0x13], [0xFFFCA000, 0x13], [0xFFFCC000, 0x13], [0xFFFCE000, 0x13], [0xFFFD0000, 0x13], [0xFFFD2000, 0x13], [0xFFFD4000, 0x13], [0xFFFD6000, 0x13], [0xFFFD8000, 0x13], [0xFFFDA000, 0x13], [0xFFFDC000, 0x13], [0xFFFDE000, 0x13], [0xFFFE0000, 0x13], [0xFFFE2000, 0x13], [0xFFFE4000, 0x13], [0xFFFE6000, 0x13], [0xFFFE8000, 0x13], [0xFFFEA000, 0x13], [0xFFFEC000, 0x13], [0xFFFEE000, 0x13], [0xFFFF0000, 0x13], [0xFFFF2000, 0x13], [0xFFFF4000, 0x13], [0xFFFF6000, 0x13], [0xFFFF8000, 0x13], [0xFFFFA000, 0x13], [0xFFFFC000, 0x13], [0xFFFFE000, 0x13], [0x00000000, 0x00], [0x00000000, 0x00] ]; /** * Initialize the Lzpf class. * * @returns {undefined} */ constructor() { this.clear(); } /** * Sets starting values for the compression algorithm. * * @returns {undefined} */ clear() { this.current_length = 0; this.current_literal = 0; this.flag_table.fill(0xFFFF, 0, 0x1000); this.compressed_data = []; } /** * Encodes a literal onto the compressed byte array. * * @param code_length {Number} bit length of the code * @param code {Number} code to be encoded * * @returns {undefined} */ EncodeLiteral(code_length, code) { // Using >>> to stick with unsigned integers without making a mess with casting. this.current_literal |= code >>> (this.current_length & 0x1F); this.current_length += code_length; while (this.current_length > 7) { //console.log("add", this.current_literal >>> 0, code >>> 0, byte, type) this.compressed_data.push((this.current_literal >>> 0x18) & 0xFF); this.current_length -= 8; this.current_literal = (this.current_literal << 8) & 0xFFFFFFFF; } } /** * Compress data using WebTV's Lzpf compression algorithm and adds the footer to the end. * * @param uncompressed_data {String} data to compress * * @returns {Buffer} Lzpf compression data */ Compress(uncompressed_data) { this.clear(); if (uncompressed_data.words) { uncompressed_data = new Buffer.from(this.wordArrayToUint8Array(uncompressed_data)); } else { uncompressed_data = new Buffer.from(uncompressed_data); } var uncompressed_len = uncompressed_data.length; var i = 0; var sum = 0; var working_data = 0; var flag = 0xFFFF; var flags_index = 0; var match_index = 0; var type_index = 0; while(i < uncompressed_len) { var code_length = -1; var code = -1; var byte = uncompressed_data.readUInt8(i); if(match_index > 0) { if (byte != uncompressed_data.readUInt8(flag) || match_index > 0x0127) { code_length = this.matchEncode[match_index][1]; code = this.matchEncode[match_index][0]; match_index = 0; type_index = 3; } else { match_index++; flag++; sum = (sum + byte) & 0xFFFF; working_data = ((working_data * 0x0100) + byte) & 0xFFFFFFFF; i++; } } else { flag = 0xFFFF; if (i >= 3) { flags_index = (working_data >>> 0x0B ^ working_data) & 0x0FFF; flag = this.flag_table[flags_index]; this.flag_table[flags_index] = i; } else { type_index++; } if (flag == 0xFFFF) { code_length = this.nomatchEncode[byte][1]; code = this.nomatchEncode[byte][0] << 0x10; } else if (byte == uncompressed_data.readUInt8(flag)) { match_index = 1; flag++; type_index = 4; } else { code_length = this.nomatchEncode[byte][1] + 1; code = this.nomatchEncode[byte][0] << 0x0F; } sum = (sum + byte) & 0xFFFF; working_data = ((working_data * 0x0100) + byte) & 0xFFFFFFFF; i++; } if (code_length > 0) { this.EncodeLiteral(code_length, code); } } // Finish up. This would normally be in an Lzpf_Finish method. if(type_index == 2) { this.EncodeLiteral(0x10, 0x00990000); } else if(type_index >= 3) { if(type_index == 4) { code_length = this.matchEncode[match_index][1]; code = this.matchEncode[match_index][0]; this.EncodeLiteral(code_length, code); } flags_index = (working_data >>> 0x0B ^ working_data) & 0x0FFF; if (flags_index == 0xFFFF) { this.EncodeLiteral(0x10, 0x00990000); } else { this.EncodeLiteral(0x11, 0x004c8000); } } // Below is just metadata. The compressed block is complete. // Encode checksum this.EncodeLiteral(0x08, (sum << 0x10) & 0xFFFFFFFF); this.EncodeLiteral(0x08, (sum << 0x18) & 0xFFFFFFFF); // End this.compressed_data.push(this.current_literal >>> 0x18); this.compressed_data.push(0x20); return new Buffer.from(this.compressed_data); } } module.exports = WTVLzpf;