zlib.js

var zlib = function (Worker, fromCharCode) {
    "use strict";
    var osList = ["FAT", "Amiga", "VMS", "Unix", "VM/CMS", "Atari TOS", "HPFS", "Macintosh", "Z-System", "CP/M", "TOPS-20",
        "NTFS", "QDOS", "Acorn RISCOS"];

    var jsPath = (jsPath = (jsPath = document.getElementsByTagName('script'))[jsPath.length - 1].src).substr(0, jsPath
            .lastIndexOf('/') + 1);

    var crc_table = Array(256);

    for (var i = 0; i < 256; i++) {
        var c = i;
        for (var j = 0; j < 8; j++) {
            var cr = c & 1;
            c = c >> 1 & 0x7FFFFFFF;
            if (cr) {
                c ^= 0xedb88320;
            }
        }
        crc_table[i] = c;
    }

    function WorkerFactory(filename) {
        var jobs = {}, getWorker = function () {
            var worker = new Worker(jsPath + filename);
            worker.addEventListener('message', function (e) {
                var ret = e.data, id = ret.id, cb = jobs[id];
                delete jobs[id];
                cb[0](ret.buffer);
            });
            getWorker = function () {
                return worker;
            };
            return worker;
        };
        return function (buffer) {
            var args = Array.prototype.slice.call(arguments);
            return new Promise(function (resolve, reject) {
                var id = uuid();
                jobs[id] = arguments;
                getWorker().postMessage({id: id, args: args}, [buffer]);
            });
        };
    }

    var zlib = {
        uuid: uuid,
        crc32: function crc32(buffer, i, end, crc) {
            for (; i < end; i++) {
                crc = crc_table[crc & 0xFF ^ buffer[i]] ^ (crc >> 8 & 0xFFFFFF);
            }
            return crc;
        },
        utf8_encode: function (str) {
            var buffer = new DataView(new ArrayBuffer(str.length * 3 + 1)), length = 0;
            for (var i = 0; i < str.length; i++) {
                var char = str.charCodeAt(i);
                if (char < 0x80) {
                    buffer.setUint8(length++, char);
                } else if (char < 0x800) {
                    buffer.setUint16(length, 0xC080 | (char & 0x7C0) << 2 | char & 0x3F);
                    length += 2;
                } else {
                    buffer.setUint32(length, (0xE08080 | (char & 0xF000) << 4 | (char & 0xFC0) << 2 | char & 0x3F) << 8);
                    length += 3;
                }
            }
            return buffer.buffer.slice(0, length);
        },
        utf8_decode: function utf8_decode(buffer) {
            var str = '', array = new Uint8Array(buffer);
            for (var idx = 0, len = array.length; idx < len;) {
                var ch = array[idx++];
                if (ch > 0x7F) {
                    if (ch > 0xDF) {// 1110 xxxx; 10xx xxxx; 10xx xxxx
                        ch = (ch & 0xF) << 12 | (array[idx++] & 0x3F) << 6 | array[idx++] & 0x3F;
                    } else { // 110x xxxx; 10xx xxxx
                        ch = (ch & 0x1F) << 6 | array[idx++] & 0x3F;
                    }
                }// 0xxx xxxx
                str += fromCharCode(ch);
            }
            return str;
        },
        deflate: WorkerFactory('deflate.js'),
        /**
         * @param {ArrayBuffer} buffer
         * @param {boolean} [headless]
         * @param {boolean} [offset]
         * @returns {Promise.<ArrayBuffer>}
         */
        inflate: WorkerFactory('inflate.js'),
        gzip: function (buffer, level, cb) {
            var originLen = buffer.byteLength, crc = zlib.crc32(buffer);
            zlib.deflate(buffer, level, function (buffer) {
                var byteLength = buffer.byteLength;
                var ret = new ArrayBuffer(byteLength + 18);// TODO
                var view = new DataView(ret);
                view.setUint32(0, 0x1F8B0800);
                view.setUint32(4, Date.now() / 1000, true);
                view.setUint16(8, 0x00FF);
                new Uint8Array(ret).set(new Uint8Array(buffer), 10);
                view.setUint32(byteLength + 10, crc);// TODO: crc32
                view.setUint32(byteLength + 14, originLen, true);
                cb(ret);
            });
        },
        gunzip: function (buffer, cb) {
            var data = new DataView(buffer);
            if ((data.getUint32(0) | 31) != 0x1F8B081F)
                throw "wrong gzip magic";
            var flags = data.getUint8(3);
            var ret = {
                mtime: new Date(data.getUint32(4, true) * 1000),
                os: osList[data.getUint8(9)]
            };
            var currPos = 10;
            if (flags & 4) {// extra
                var extraLen = data.getUint16(10);
                // TODO: read extra info
                currPos += extraLen + 2;
            }
            if (flags & 8) {// fileName
                var idx = Array.prototype.indexOf.call(new Uint8Array(buffer, currPos), 0);
                ret.fileName = fromCharCode.apply(null, new Uint8Array(buffer, currPos, idx));
                currPos += idx + 1;
            }
            if (flags & 16) { // comment
                var idx = Array.prototype.indexOf.call(new Uint8Array(buffer, currPos), 0);
                ret.comment = fromCharCode.apply(null, new Uint8Array(buffer, currPos, idx));
                currPos += idx + 1;
            }
            if (flags & 2) {
                // TODO: header CRC16
                currPos += 2;
            }
            zlib.inflate(buffer, true, function (buffer) {
                ret.buffer = buffer;
                cb(ret);
            }, currPos);
            // TODO: CRC32
        }
    };
    return zlib;
    function uuid() {
        return (Date.now() * (Math.random() + 0.5)).toString(36);
    }
}(Worker, String.fromCharCode);