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Add deflator helper class for deflating data
Wraps pako's deflate for easier usage.
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79
kasmweb/core/deflator.js
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79
kasmweb/core/deflator.js
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/*
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* noVNC: HTML5 VNC client
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* Copyright (C) 2020 The noVNC Authors
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* Licensed under MPL 2.0 (see LICENSE.txt)
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*
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* See README.md for usage and integration instructions.
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*/
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import { deflateInit, deflate } from "../vendor/pako/lib/zlib/deflate.js";
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import { Z_FULL_FLUSH } from "../vendor/pako/lib/zlib/deflate.js";
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import ZStream from "../vendor/pako/lib/zlib/zstream.js";
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export default class Deflator {
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constructor() {
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this.strm = new ZStream();
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this.chunkSize = 1024 * 10 * 10;
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this.outputBuffer = new Uint8Array(this.chunkSize);
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this.windowBits = 5;
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deflateInit(this.strm, this.windowBits);
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}
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deflate(inData) {
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this.strm.input = inData;
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this.strm.avail_in = this.strm.input.length;
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this.strm.next_in = 0;
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this.strm.output = this.outputBuffer;
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this.strm.avail_out = this.chunkSize;
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this.strm.next_out = 0;
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let lastRet = deflate(this.strm, Z_FULL_FLUSH);
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let outData = new Uint8Array(this.strm.output.buffer, 0, this.strm.next_out);
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if (lastRet < 0) {
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throw new Error("zlib deflate failed");
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}
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if (this.strm.avail_in > 0) {
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// Read chunks until done
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let chunks = [outData];
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let totalLen = outData.length;
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do {
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this.strm.output = new Uint8Array(this.chunkSize);
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this.strm.next_out = 0;
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this.strm.avail_out = this.chunkSize;
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lastRet = deflate(this.strm, Z_FULL_FLUSH);
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if (lastRet < 0) {
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throw new Error("zlib deflate failed");
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}
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let chunk = new Uint8Array(this.strm.output.buffer, 0, this.strm.next_out);
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totalLen += chunk.length;
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chunks.push(chunk);
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} while (this.strm.avail_in > 0);
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// Combine chunks into a single data
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let newData = new Uint8Array(totalLen);
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let offset = 0;
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for (let i = 0; i < chunks.length; i++) {
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newData.set(chunks[i], offset);
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offset += chunks[i].length;
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}
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outData = newData;
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}
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this.strm.input = null;
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this.strm.avail_in = 0;
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this.strm.next_in = 0;
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return outData;
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}
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}
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kasmweb/tests/test.deflator.js
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kasmweb/tests/test.deflator.js
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/* eslint-disable no-console */
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const expect = chai.expect;
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import { inflateInit, inflate } from "../vendor/pako/lib/zlib/inflate.js";
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import ZStream from "../vendor/pako/lib/zlib/zstream.js";
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import Deflator from "../core/deflator.js";
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function _inflator(compText, expected) {
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let strm = new ZStream();
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let chunkSize = 1024 * 10 * 10;
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strm.output = new Uint8Array(chunkSize);
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inflateInit(strm, 5);
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if (expected > chunkSize) {
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chunkSize = expected;
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strm.output = new Uint8Array(chunkSize);
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}
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strm.input = compText;
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strm.avail_in = strm.input.length;
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strm.next_in = 0;
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strm.next_out = 0;
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strm.avail_out = expected.length;
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let ret = inflate(strm, 0);
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// Check that return code is not an error
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expect(ret).to.be.greaterThan(-1);
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return new Uint8Array(strm.output.buffer, 0, strm.next_out);
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}
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describe('Deflate data', function () {
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it('should be able to deflate messages', function () {
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let deflator = new Deflator();
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let text = "123asdf";
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let preText = new Uint8Array(text.length);
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for (let i = 0; i < preText.length; i++) {
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preText[i] = text.charCodeAt(i);
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}
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let compText = deflator.deflate(preText);
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let inflatedText = _inflator(compText, text.length);
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expect(inflatedText).to.array.equal(preText);
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});
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it('should be able to deflate large messages', function () {
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let deflator = new Deflator();
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/* Generate a big string with random characters. Used because
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repetition of letters might be deflated more effectively than
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random ones. */
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let text = "";
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let characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
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for (let i = 0; i < 300000; i++) {
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text += characters.charAt(Math.floor(Math.random() * characters.length));
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}
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let preText = new Uint8Array(text.length);
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for (let i = 0; i < preText.length; i++) {
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preText[i] = text.charCodeAt(i);
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}
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let compText = deflator.deflate(preText);
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//Check that the compressed size is expected size
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expect(compText.length).to.be.greaterThan((1024 * 10 * 10) * 2);
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let inflatedText = _inflator(compText, text.length);
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expect(inflatedText).to.array.equal(preText);
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});
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});
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60
kasmweb/vendor/pako/lib/zlib/deflate.js
vendored
60
kasmweb/vendor/pako/lib/zlib/deflate.js
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/* Allowed flush values; see deflate() and inflate() below for details */
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/* Allowed flush values; see deflate() and inflate() below for details */
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var Z_NO_FLUSH = 0;
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export const Z_NO_FLUSH = 0;
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var Z_PARTIAL_FLUSH = 1;
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export const Z_PARTIAL_FLUSH = 1;
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//var Z_SYNC_FLUSH = 2;
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//export const Z_SYNC_FLUSH = 2;
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var Z_FULL_FLUSH = 3;
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export const Z_FULL_FLUSH = 3;
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var Z_FINISH = 4;
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export const Z_FINISH = 4;
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var Z_BLOCK = 5;
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export const Z_BLOCK = 5;
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//var Z_TREES = 6;
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//export const Z_TREES = 6;
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/* Return codes for the compression/decompression functions. Negative values
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/* Return codes for the compression/decompression functions. Negative values
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* are errors, positive values are used for special but normal events.
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* are errors, positive values are used for special but normal events.
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*/
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*/
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var Z_OK = 0;
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export const Z_OK = 0;
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var Z_STREAM_END = 1;
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export const Z_STREAM_END = 1;
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//var Z_NEED_DICT = 2;
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//export const Z_NEED_DICT = 2;
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//var Z_ERRNO = -1;
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//export const Z_ERRNO = -1;
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var Z_STREAM_ERROR = -2;
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export const Z_STREAM_ERROR = -2;
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var Z_DATA_ERROR = -3;
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export const Z_DATA_ERROR = -3;
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//var Z_MEM_ERROR = -4;
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//export const Z_MEM_ERROR = -4;
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var Z_BUF_ERROR = -5;
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export const Z_BUF_ERROR = -5;
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//var Z_VERSION_ERROR = -6;
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//export const Z_VERSION_ERROR = -6;
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/* compression levels */
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/* compression levels */
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//var Z_NO_COMPRESSION = 0;
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//export const Z_NO_COMPRESSION = 0;
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//var Z_BEST_SPEED = 1;
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//export const Z_BEST_SPEED = 1;
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//var Z_BEST_COMPRESSION = 9;
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//export const Z_BEST_COMPRESSION = 9;
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var Z_DEFAULT_COMPRESSION = -1;
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export const Z_DEFAULT_COMPRESSION = -1;
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var Z_FILTERED = 1;
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export const Z_FILTERED = 1;
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var Z_HUFFMAN_ONLY = 2;
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export const Z_HUFFMAN_ONLY = 2;
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var Z_RLE = 3;
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export const Z_RLE = 3;
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var Z_FIXED = 4;
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export const Z_FIXED = 4;
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var Z_DEFAULT_STRATEGY = 0;
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export const Z_DEFAULT_STRATEGY = 0;
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/* Possible values of the data_type field (though see inflate()) */
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/* Possible values of the data_type field (though see inflate()) */
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//var Z_BINARY = 0;
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//export const Z_BINARY = 0;
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//var Z_TEXT = 1;
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//export const Z_TEXT = 1;
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//var Z_ASCII = 1; // = Z_TEXT
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//export const Z_ASCII = 1; // = Z_TEXT
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var Z_UNKNOWN = 2;
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export const Z_UNKNOWN = 2;
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/* The deflate compression method */
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/* The deflate compression method */
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var Z_DEFLATED = 8;
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export const Z_DEFLATED = 8;
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/*============================================================================*/
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/*============================================================================*/
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