lkarch.org/tools/microsoft-flight-simulator/bzip2.js

/*
  bzip2.js - a small bzip2 decompression implementation

  Copyright 2011 by antimatter15 (antimatter15@gmail.com)

  Based on micro-bunzip by Rob Landley (rob@landley.net).
  Copyright (c) 2011 by antimatter15 (antimatter15@gmail.com).
  Permission is hereby granted, free of charge, to any person obtaining a
  copy of this software and associated documentation files (the "Software"),
  to deal in the Software without restriction, including without limitation
  the rights to use, copy, modify, merge, publish, distribute, sublicense,
  and/or sell copies of the Software, and to permit persons to whom the
  Software is furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included
  in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH
  THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

let bzip2 = {};

bzip2.crcTable =
    [
        0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
        0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
        0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
        0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
        0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
        0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
        0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
        0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
        0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
        0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
        0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
        0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
        0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
        0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
        0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
        0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
        0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
        0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
        0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
        0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
        0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
        0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
        0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
        0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
        0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
        0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
        0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
        0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
        0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
        0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
        0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
        0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
        0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
        0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
        0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
        0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
        0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
        0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
        0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
        0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
        0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
        0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
        0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
        0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
        0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
        0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
        0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
        0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
        0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
        0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
        0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
        0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
        0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
        0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
        0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
        0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
        0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
        0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
        0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
        0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
        0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
        0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
        0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
        0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
    ];

bzip2.array = function(bytes) {
    var bit = 0, byte = 0;
    var BITMASK = [0, 0x01, 0x03, 0x07, 0x0F, 0x1F, 0x3F, 0x7F, 0xFF ];
    return function(n) {
        var result = 0;
        while(n > 0) {
            var left = 8 - bit;
            if (n >= left) {
                result <<= left;
                result |= (BITMASK[left] & bytes[byte++]);
                bit = 0;
                n -= left;
            } else {
                result <<= n;
                result |= ((bytes[byte] & (BITMASK[n] << (8 - n - bit))) >> (8 - n - bit));
                bit += n;
                n = 0;
            }
        }
        return result;
    }
}

bzip2.IsBZIP2 = function(buffer) {
    if ((buffer[0] == 0x42) && (buffer[1] == 0x5A) && (buffer[2] == 0x68)) return true;
    return false;
}


bzip2.simple = function(srcbuffer, stream) {
    var bits = bzip2.array(srcbuffer);
    var size = bzip2.header(bits);
    var ret = false;
    var bufsize = 100000 * size;
    var buf = new Int32Array(bufsize);

    this.byteCount = new Int32Array(256);
    this.symToByte = new Uint8Array(256);
    this.mtfSymbol = new Int32Array(256);
    this.selectors = new Uint8Array(0x8000);

    do {
        ret = bzip2.decompress(bits, stream, buf, bufsize);
    } while(!ret);
}

bzip2.header = function(bits) {
    if (bits(8*3) !== 4348520) console.log("No magic number found");
    const i = bits(8) - 48;
    if (i < 1 || i > 9) console.log("Not a BZIP archive");
    return i;
};


//takes a function for reading the block data (starting with 0x314159265359)
//a block size (0-9) (optional, defaults to 9)
//a length at which to stop decompressing and return the output
bzip2.decompress = function(bits, stream, buf, bufsize) {
    let limit;
    let base;
    let uc;
    let k;
    let j;
    const MAX_HUFCODE_BITS = 20;
    const MAX_SYMBOLS = 258;
    const SYMBOL_RUNA = 0;
    const SYMBOL_RUNB = 1;
    const GROUP_SIZE = 50;
    let crc = 0 ^ (-1);

    var h = '';
    let i = 0;
    for(; i < 6; i++) h += bits(8).toString(16);
    if (h == "177245385090") return true; //last block
    if (h != "314159265359") console.log("eek not valid bzip data");
    let crcblock = bits(32) | 0; // CRC code
    if (bits(1)) console.log("unsupported obsolete version");
    let origPtr = bits(24);
    if (origPtr > bufsize) console.log("Initial position larger than buffer size");
    let t = bits(16);
    let symTotal = 0;
    for (i = 0; i < 16; i++) {
        if (t & (1 << (15 - i))) {
            k = bits(16);
            for(j = 0; j < 16; j++) {
                if (k & (1 << (15 - j))) {
                    this.symToByte[symTotal++] = (16 * i) + j;
                }
            }
        }
    }

    let groupCount = bits(3);
    if (groupCount < 2 || groupCount > 6) console.log("another error");
    let nSelectors = bits(15);
    if (nSelectors == 0) console.log("meh");
    for(i = 0; i < groupCount; i++) this.mtfSymbol[i] = i;

    for(i = 0; i < nSelectors; i++) {
        for(j = 0; bits(1); j++) if (j >= groupCount) console.log("whoops another error");
        uc = this.mtfSymbol[j];
        for(k = j-1; k>=0; k--) {
            this.mtfSymbol[k+1] = this.mtfSymbol[k];
        }
        this.mtfSymbol[0] = uc;
        this.selectors[i] = uc;
    }

    let symCount = symTotal + 2;
    let groups = [];
    let length = new Uint8Array(MAX_SYMBOLS),
        temp = new Uint8Array(MAX_HUFCODE_BITS + 1);

    let hufGroup;

    for(j = 0; j < groupCount; j++) {
        t = bits(5); //lengths
        for(i = 0; i < symCount; i++) {
            while(true){
                if (t < 1 || t > MAX_HUFCODE_BITS) console.log("I gave up a while ago on writing error messages");
                if (!bits(1)) break;
                if (!bits(1)) t++;
                else t--;
            }
            length[i] = t;
        }
        let minLen, maxLen;
        minLen = maxLen = length[0];
        for(i = 1; i < symCount; i++) {
            if (length[i] > maxLen) maxLen = length[i];
            else if (length[i] < minLen) minLen = length[i];
        }
        hufGroup = groups[j] = {};
        hufGroup.permute = new Int32Array(MAX_SYMBOLS);
        hufGroup.limit = new Int32Array(MAX_HUFCODE_BITS + 1);
        hufGroup.base = new Int32Array(MAX_HUFCODE_BITS + 1);

        hufGroup.minLen = minLen;
        hufGroup.maxLen = maxLen;
        base = hufGroup.base.subarray(1);
        limit = hufGroup.limit.subarray(1);
        let pp = 0;
        for(i = minLen; i <= maxLen; i++)
            for(t = 0; t < symCount; t++)
                if (length[t] == i) hufGroup.permute[pp++] = t;
        for(i = minLen; i <= maxLen; i++) temp[i] = limit[i] = 0;
        for(i = 0; i < symCount; i++) temp[length[i]]++;
        pp = t = 0;
        for(i = minLen; i < maxLen; i++) {
            pp += temp[i];
            limit[i] = pp - 1;
            pp <<= 1;
            base[i+1] = pp - (t += temp[i]);
        }
        limit[maxLen] = pp + temp[maxLen] - 1;
        base[minLen] = 0;
    }

    for(i = 0; i < 256; i++) {
        this.mtfSymbol[i] = i;
        this.byteCount[i] = 0;
    }
    let runPos;
    let count;
    let selector;
    runPos = count = symCount = selector = 0;
    while(true) {
        if (!(symCount--)) {
            symCount = GROUP_SIZE - 1;
            if (selector >= nSelectors) console.log("meow i'm a kitty, that's an error");
            hufGroup = groups[this.selectors[selector++]];
            base = hufGroup.base.subarray(1);
            limit = hufGroup.limit.subarray(1);
        }
        i = hufGroup.minLen;
        j = bits(i);
        while(true) {
            if (i > hufGroup.maxLen) console.log("rawr i'm a dinosaur");
            if (j <= limit[i]) break;
            i++;
            j = (j << 1) | bits(1);
        }
        j -= base[i];
        if (j < 0 || j >= MAX_SYMBOLS) console.log("moo i'm a cow");
        let nextSym = hufGroup.permute[j];
        if (nextSym == SYMBOL_RUNA || nextSym == SYMBOL_RUNB) {
            if (!runPos){
                runPos = 1;
                t = 0;
            }
            if (nextSym == SYMBOL_RUNA) t += runPos;
            else t += 2 * runPos;
            runPos <<= 1;
            continue;
        }
        if (runPos) {
            runPos = 0;
            if (count + t >= bufsize) console.log("Boom.");
            uc = this.symToByte[this.mtfSymbol[0]];
            this.byteCount[uc] += t;
            while(t--) buf[count++] = uc;
        }
        if (nextSym > symTotal) break;
        if (count >= bufsize) console.log("I can't think of anything. Error");
        i = nextSym - 1;
        uc = this.mtfSymbol[i];
        for(k = i-1; k>=0; k--) {
            this.mtfSymbol[k+1] = this.mtfSymbol[k];
        }
        this.mtfSymbol[0] = uc
        uc = this.symToByte[uc];
        this.byteCount[uc]++;
        buf[count++] = uc;
    }
    if (origPtr < 0 || origPtr >= count) console.log("I'm a monkey and I'm throwing something at someone, namely you");
    j = 0;
    for(i = 0; i < 256; i++) {
        k = j + this.byteCount[i];
        this.byteCount[i] = j;
        j = k;
    }
    for(i = 0; i < count; i++) {
        uc = buf[i] & 0xff;
        buf[this.byteCount[uc]] |= (i << 8);
        this.byteCount[uc]++;
    }
    let pos = 0, current = 0, run = 0;
    if (count) {
        pos = buf[origPtr];
        current = (pos & 0xff);
        pos >>= 8;
        run = -1;
    }
    let copies, previous, outbyte;
    while(count) {
        count--;
        previous = current;
        pos = buf[pos];
        current = pos & 0xff;
        pos >>= 8;
        if (run++ == 3) {
            copies = current;
            outbyte = previous;
            current = -1;
        } else {
            copies = 1;
            outbyte = current;
        }
        while(copies--) {
            crc = ((crc << 8) ^ this.crcTable[((crc>>24) ^ outbyte) & 0xFF])&0xFFFFFFFF; // crc32
            stream(outbyte);
        }
        if (current != previous) run = 0;
    }

    crc = (crc ^ (-1)) >>> 0;
    if ((crc|0) != (crcblock|0)) console.log("Error in bzip2: crc32 do not match");
    return false;
}