Merge remote-tracking branch 'Comic/comic_server'
# Conflicts: # cps/helper.py # cps/static/js/archive.js # cps/static/js/io.js # cps/static/js/kthoom.js # cps/static/js/unrar.js # cps/static/js/untar.js # cps/static/js/unzip.js # cps/templates/config_edit.html # cps/templates/detail.html # cps/templates/readcbr.html # cps/templates/stats.html # cps/ub.py # cps/web.py # optional-requirements.txtpull/598/merge
OzzieIsaacs
6 years ago
commit
3f35200a0b
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/*
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* bytestream.js
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*
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* Provides readers for byte streams.
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*
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* Licensed under the MIT License
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*
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* Copyright(c) 2011 Google Inc.
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* Copyright(c) 2011 antimatter15
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*/
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var bitjs = bitjs || {};
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bitjs.io = bitjs.io || {};
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/**
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* This object allows you to peek and consume bytes as numbers and strings out
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* of a stream. More bytes can be pushed into the back of the stream via the
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* push() method.
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*/
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bitjs.io.ByteStream = class {
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/**
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* @param {ArrayBuffer} ab The ArrayBuffer object.
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* @param {number=} opt_offset The offset into the ArrayBuffer
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* @param {number=} opt_length The length of this BitStream
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*/
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constructor(ab, opt_offset, opt_length) {
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if (!(ab instanceof ArrayBuffer)) {
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throw 'Error! BitArray constructed with an invalid ArrayBuffer object';
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}
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const offset = opt_offset || 0;
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const length = opt_length || ab.byteLength;
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/**
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* The current page of bytes in the stream.
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* @type {Uint8Array}
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* @private
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*/
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this.bytes = new Uint8Array(ab, offset, length);
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/**
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* The next pages of bytes in the stream.
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* @type {Array<Uint8Array>}
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* @private
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*/
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this.pages_ = [];
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/**
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* The byte in the current page that we will read next.
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* @type {Number}
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* @private
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*/
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this.ptr = 0;
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/**
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* An ever-increasing number.
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* @type {Number}
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* @private
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*/
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this.bytesRead_ = 0;
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}
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/**
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* Returns how many bytes have been read in the stream since the beginning of time.
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*/
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getNumBytesRead() {
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return this.bytesRead_;
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}
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/**
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* Returns how many bytes are currently in the stream left to be read.
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*/
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getNumBytesLeft() {
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const bytesInCurrentPage = (this.bytes.byteLength - this.ptr);
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return this.pages_.reduce((acc, arr) => acc + arr.length, bytesInCurrentPage);
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}
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/**
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* Move the pointer ahead n bytes. If the pointer is at the end of the current array
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* of bytes and we have another page of bytes, point at the new page. This is a private
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* method, no validation is done.
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* @param {number} n Number of bytes to increment.
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* @private
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*/
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movePointer_(n) {
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this.ptr += n;
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this.bytesRead_ += n;
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while (this.ptr >= this.bytes.length && this.pages_.length > 0) {
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this.ptr -= this.bytes.length;
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this.bytes = this.pages_.shift();
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}
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}
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/**
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* Peeks at the next n bytes as an unsigned number but does not advance the
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* pointer.
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* @param {number} n The number of bytes to peek at. Must be a positive integer.
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* @return {number} The n bytes interpreted as an unsigned number.
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*/
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peekNumber(n) {
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const num = parseInt(n, 10);
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if (n !== num || num < 0) {
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throw 'Error! Called peekNumber() with a non-positive integer';
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} else if (num === 0) {
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return 0;
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}
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if (n > 4) {
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throw 'Error! Called peekNumber(' + n +
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') but this method can only reliably read numbers up to 4 bytes long';
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}
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if (this.getNumBytesLeft() < num) {
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throw 'Error! Overflowed the byte stream while peekNumber()! n=' + num +
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', ptr=' + this.ptr + ', bytes.length=' + this.getNumBytesLeft();
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}
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let result = 0;
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let curPage = this.bytes;
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let pageIndex = 0;
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let ptr = this.ptr;
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for (let i = 0; i < num; ++i) {
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result |= (curPage[ptr++] << (i * 8));
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if (ptr >= curPage.length) {
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curPage = this.pages_[pageIndex++];
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ptr = 0;
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}
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}
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return result;
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}
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/**
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* Returns the next n bytes as an unsigned number (or -1 on error)
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* and advances the stream pointer n bytes.
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* @param {number} n The number of bytes to read. Must be a positive integer.
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* @return {number} The n bytes interpreted as an unsigned number.
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*/
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readNumber(n) {
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const num = this.peekNumber(n);
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this.movePointer_(n);
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return num;
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}
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/**
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* Returns the next n bytes as a signed number but does not advance the
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* pointer.
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* @param {number} n The number of bytes to read. Must be a positive integer.
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* @return {number} The bytes interpreted as a signed number.
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*/
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peekSignedNumber(n) {
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let num = this.peekNumber(n);
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const HALF = Math.pow(2, (n * 8) - 1);
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const FULL = HALF * 2;
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if (num >= HALF) num -= FULL;
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return num;
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}
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/**
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* Returns the next n bytes as a signed number and advances the stream pointer.
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* @param {number} n The number of bytes to read. Must be a positive integer.
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* @return {number} The bytes interpreted as a signed number.
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*/
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readSignedNumber(n) {
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const num = this.peekSignedNumber(n);
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this.movePointer_(n);
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return num;
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}
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/**
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* This returns n bytes as a sub-array, advancing the pointer if movePointers
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* is true.
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* @param {number} n The number of bytes to read. Must be a positive integer.
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* @param {boolean} movePointers Whether to move the pointers.
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* @return {Uint8Array} The subarray.
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*/
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peekBytes(n, movePointers) {
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const num = parseInt(n, 10);
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if (n !== num || num < 0) {
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throw 'Error! Called peekBytes() with a non-positive integer';
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} else if (num === 0) {
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return new Uint8Array();
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}
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const totalBytesLeft = this.getNumBytesLeft();
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if (num > totalBytesLeft) {
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throw 'Error! Overflowed the byte stream during peekBytes! n=' + num +
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', ptr=' + this.ptr + ', bytes.length=' + this.getNumBytesLeft();
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}
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const result = new Uint8Array(num);
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let curPage = this.bytes;
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let ptr = this.ptr;
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let bytesLeftToCopy = num;
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let pageIndex = 0;
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while (bytesLeftToCopy > 0) {
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const bytesLeftInPage = curPage.length - ptr;
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const sourceLength = Math.min(bytesLeftToCopy, bytesLeftInPage);
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result.set(curPage.subarray(ptr, ptr + sourceLength), num - bytesLeftToCopy);
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ptr += sourceLength;
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if (ptr >= curPage.length) {
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curPage = this.pages_[pageIndex++];
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ptr = 0;
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}
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bytesLeftToCopy -= sourceLength;
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}
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if (movePointers) {
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this.movePointer_(num);
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}
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return result;
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}
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/**
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* Reads the next n bytes as a sub-array.
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* @param {number} n The number of bytes to read. Must be a positive integer.
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* @return {Uint8Array} The subarray.
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*/
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readBytes(n) {
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return this.peekBytes(n, true);
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}
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/**
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* Peeks at the next n bytes as an ASCII string but does not advance the pointer.
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* @param {number} n The number of bytes to peek at. Must be a positive integer.
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* @return {string} The next n bytes as a string.
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*/
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peekString(n) {
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const num = parseInt(n, 10);
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if (n !== num || num < 0) {
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throw 'Error! Called peekString() with a non-positive integer';
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} else if (num === 0) {
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return '';
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}
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const totalBytesLeft = this.getNumBytesLeft();
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if (num > totalBytesLeft) {
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throw 'Error! Overflowed the byte stream while peekString()! n=' + num +
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', ptr=' + this.ptr + ', bytes.length=' + this.getNumBytesLeft();
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}
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let result = new Array(num);
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let curPage = this.bytes;
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let pageIndex = 0;
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let ptr = this.ptr;
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for (let i = 0; i < num; ++i) {
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result[i] = String.fromCharCode(curPage[ptr++]);
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if (ptr >= curPage.length) {
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curPage = this.pages_[pageIndex++];
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ptr = 0;
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}
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}
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return result.join('');
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}
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/**
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* Returns the next n bytes as an ASCII string and advances the stream pointer
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* n bytes.
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* @param {number} n The number of bytes to read. Must be a positive integer.
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* @return {string} The next n bytes as a string.
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*/
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readString(n) {
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const strToReturn = this.peekString(n);
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this.movePointer_(n);
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return strToReturn;
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}
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/**
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* Feeds more bytes into the back of the stream.
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* @param {ArrayBuffer} ab
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*/
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push(ab) {
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if (!(ab instanceof ArrayBuffer)) {
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throw 'Error! ByteStream.push() called with an invalid ArrayBuffer object';
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}
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this.pages_.push(new Uint8Array(ab));
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// If the pointer is at the end of the current page of bytes, this will advance
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// to the next page.
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this.movePointer_(0);
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}
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/**
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* Creates a new ByteStream from this ByteStream that can be read / peeked.
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* @return {bitjs.io.ByteStream} A clone of this ByteStream.
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*/
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tee() {
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const clone = new bitjs.io.ByteStream(this.bytes.buffer);
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clone.bytes = this.bytes;
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clone.ptr = this.ptr;
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clone.pages_ = this.pages_.slice();
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clone.bytesRead_ = this.bytesRead_;
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return clone;
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}
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}
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