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@ -14,17 +14,17 @@ bitjs.io = bitjs.io || {};
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(function() {
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// mask for getting the Nth bit (zero-based)
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bitjs.BIT = [ 0x01, 0x02, 0x04, 0x08,
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// mask for getting the Nth bit (zero-based)
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bitjs.BIT = [ 0x01, 0x02, 0x04, 0x08,
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0x10, 0x20, 0x40, 0x80,
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0x100, 0x200, 0x400, 0x800,
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0x1000, 0x2000, 0x4000, 0x8000];
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// mask for getting N number of bits (0-8)
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var BITMASK = [0, 0x01, 0x03, 0x07, 0x0F, 0x1F, 0x3F, 0x7F, 0xFF ];
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// mask for getting N number of bits (0-8)
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var BITMASK = [0, 0x01, 0x03, 0x07, 0x0F, 0x1F, 0x3F, 0x7F, 0xFF ];
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/**
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/**
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* This bit stream peeks and consumes bits out of a binary stream.
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*
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* @param {ArrayBuffer} ab An ArrayBuffer object or a Uint8Array.
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@ -33,7 +33,7 @@ var BITMASK = [0, 0x01, 0x03, 0x07, 0x0F, 0x1F, 0x3F, 0x7F, 0xFF ];
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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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bitjs.io.BitStream = function(ab, rtl, opt_offset, opt_length) {
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bitjs.io.BitStream = function(ab, rtl, opt_offset, opt_length) {
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if (!ab || !ab.toString || ab.toString() !== "[object ArrayBuffer]") {
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throw "Error! BitArray constructed with an invalid ArrayBuffer object";
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}
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@ -44,10 +44,10 @@ bitjs.io.BitStream = function(ab, rtl, opt_offset, opt_length) {
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this.bytePtr = 0; // tracks which byte we are on
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this.bitPtr = 0; // tracks which bit we are on (can have values 0 through 7)
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this.peekBits = rtl ? this.peekBits_rtl : this.peekBits_ltr;
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};
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};
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/**
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/**
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* byte0 byte1 byte2 byte3
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* 7......0 | 7......0 | 7......0 | 7......0
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*
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@ -57,7 +57,7 @@ bitjs.io.BitStream = function(ab, rtl, opt_offset, opt_length) {
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* @param {boolean=} movePointers Whether to move the pointer, defaults false.
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* @return {number} The peeked bits, as an unsigned number.
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*/
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bitjs.io.BitStream.prototype.peekBits_ltr = function(n, movePointers) {
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bitjs.io.BitStream.prototype.peekBits_ltr = function(n, movePointers) {
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if (n <= 0 || typeof n != typeof 1) {
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return 0;
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}
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@ -106,10 +106,10 @@ bitjs.io.BitStream.prototype.peekBits_ltr = function(n, movePointers) {
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}
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return result;
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};
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};
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/**
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/**
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* byte0 byte1 byte2 byte3
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* 7......0 | 7......0 | 7......0 | 7......0
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*
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@ -119,7 +119,7 @@ bitjs.io.BitStream.prototype.peekBits_ltr = function(n, movePointers) {
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* @param {boolean=} movePointers Whether to move the pointer, defaults false.
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* @return {number} The peeked bits, as an unsigned number.
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*/
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bitjs.io.BitStream.prototype.peekBits_rtl = function(n, movePointers) {
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bitjs.io.BitStream.prototype.peekBits_rtl = function(n, movePointers) {
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if (n <= 0 || typeof n != typeof 1) {
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return 0;
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}
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@ -165,30 +165,30 @@ bitjs.io.BitStream.prototype.peekBits_rtl = function(n, movePointers) {
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}
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return result;
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};
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};
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/**
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/**
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* Some voodoo magic.
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*/
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bitjs.io.BitStream.prototype.getBits = function() {
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bitjs.io.BitStream.prototype.getBits = function() {
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return (((((this.bytes[this.bytePtr] & 0xff) << 16) +
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((this.bytes[this.bytePtr+1] & 0xff) << 8) +
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((this.bytes[this.bytePtr+2] & 0xff))) >>> (8-this.bitPtr)) & 0xffff);
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};
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};
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/**
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/**
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* Reads n bits out of the stream, consuming them (moving the bit pointer).
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* @param {number} n The number of bits to read.
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* @return {number} The read bits, as an unsigned number.
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*/
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bitjs.io.BitStream.prototype.readBits = function(n) {
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bitjs.io.BitStream.prototype.readBits = function(n) {
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return this.peekBits(n, true);
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};
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};
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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. Only use this for uncompressed blocks as this throws away remaining
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* bits in the current byte.
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@ -196,7 +196,7 @@ bitjs.io.BitStream.prototype.readBits = function(n) {
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* @param {boolean=} movePointers Whether to move the pointer, defaults false.
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* @return {Uint8Array} The subarray.
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*/
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bitjs.io.BitStream.prototype.peekBytes = function(n, movePointers) {
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bitjs.io.BitStream.prototype.peekBytes = function(n, movePointers) {
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if (n <= 0 || typeof n != typeof 1) {
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return 0;
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}
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@ -218,19 +218,19 @@ bitjs.io.BitStream.prototype.peekBytes = function(n, movePointers) {
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}
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return result;
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};
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};
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/**
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/**
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* @param {number} n The number of bytes to read.
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* @return {Uint8Array} The subarray.
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*/
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bitjs.io.BitStream.prototype.readBytes = function(n) {
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bitjs.io.BitStream.prototype.readBytes = function(n) {
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return this.peekBytes(n, true);
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};
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};
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/**
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/**
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* This object allows you to peek and consume bytes as numbers and strings
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* out of an ArrayBuffer. In this buffer, everything must be byte-aligned.
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*
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@ -239,22 +239,22 @@ bitjs.io.BitStream.prototype.readBytes = function(n) {
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* @param {number=} opt_length The length of this BitStream
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* @constructor
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*/
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bitjs.io.ByteStream = function(ab, opt_offset, opt_length) {
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bitjs.io.ByteStream = function(ab, opt_offset, opt_length) {
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var offset = opt_offset || 0;
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var length = opt_length || ab.byteLength;
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this.bytes = new Uint8Array(ab, offset, length);
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this.ptr = 0;
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};
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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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* TODO: This apparently cannot read more than 4 bytes as a number?
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* @param {number} n The number of bytes to peek at.
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* @return {number} The n bytes interpreted as an unsigned number.
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*/
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bitjs.io.ByteStream.prototype.peekNumber = function(n) {
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bitjs.io.ByteStream.prototype.peekNumber = function(n) {
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// TODO: return error if n would go past the end of the stream?
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if (n <= 0 || typeof n != typeof 1)
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return -1;
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@ -268,29 +268,29 @@ bitjs.io.ByteStream.prototype.peekNumber = function(n) {
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--curByte;
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}
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return result;
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};
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};
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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.
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* @return {number} The n bytes interpreted as an unsigned number.
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*/
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bitjs.io.ByteStream.prototype.readNumber = function(n) {
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bitjs.io.ByteStream.prototype.readNumber = function(n) {
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var num = this.peekNumber( n );
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this.ptr += n;
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return num;
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};
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};
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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.
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* @return {number} The bytes interpreted as a signed number.
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*/
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bitjs.io.ByteStream.prototype.peekSignedNumber = function(n) {
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bitjs.io.ByteStream.prototype.peekSignedNumber = function(n) {
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var num = this.peekNumber(n);
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var HALF = Math.pow(2, (n * 8) - 1);
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var FULL = HALF * 2;
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@ -298,29 +298,29 @@ bitjs.io.ByteStream.prototype.peekSignedNumber = function(n) {
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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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/**
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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.
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* @return {number} The bytes interpreted as a signed number.
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*/
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bitjs.io.ByteStream.prototype.readSignedNumber = function(n) {
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bitjs.io.ByteStream.prototype.readSignedNumber = function(n) {
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var num = this.peekSignedNumber(n);
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this.ptr += n;
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return num;
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};
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};
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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.
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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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bitjs.io.ByteStream.prototype.peekBytes = function(n, movePointers) {
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bitjs.io.ByteStream.prototype.peekBytes = function(n, movePointers) {
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if (n <= 0 || typeof n != typeof 1) {
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return null;
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}
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@ -332,25 +332,25 @@ bitjs.io.ByteStream.prototype.peekBytes = function(n, movePointers) {
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}
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return result;
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};
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};
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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.
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* @return {Uint8Array} The subarray.
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*/
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bitjs.io.ByteStream.prototype.readBytes = function(n) {
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bitjs.io.ByteStream.prototype.readBytes = function(n) {
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return this.peekBytes(n, true);
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};
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};
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/**
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/**
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* Peeks at the next n bytes as a string but does not advance the pointer.
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* @param {number} n The number of bytes to peek at.
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* @return {string} The next n bytes as a string.
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*/
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bitjs.io.ByteStream.prototype.peekString = function(n) {
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bitjs.io.ByteStream.prototype.peekString = function(n) {
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if (n <= 0 || typeof n != typeof 1) {
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return "";
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}
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@ -360,62 +360,62 @@ bitjs.io.ByteStream.prototype.peekString = function(n) {
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result += String.fromCharCode(this.bytes[p]);
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}
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return result;
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};
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};
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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.
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* @return {string} The next n bytes as a string.
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*/
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bitjs.io.ByteStream.prototype.readString = function(n) {
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bitjs.io.ByteStream.prototype.readString = function(n) {
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var strToReturn = this.peekString(n);
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this.ptr += n;
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return strToReturn;
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};
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};
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/**
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/**
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* A write-only Byte buffer which uses a Uint8 Typed Array as a backing store.
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* @param {number} numBytes The number of bytes to allocate.
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* @constructor
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*/
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bitjs.io.ByteBuffer = function(numBytes) {
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bitjs.io.ByteBuffer = function(numBytes) {
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if (typeof numBytes != typeof 1 || numBytes <= 0) {
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throw "Error! ByteBuffer initialized with '" + numBytes + "'";
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}
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this.data = new Uint8Array(numBytes);
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this.ptr = 0;
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};
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};
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/**
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/**
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* @param {number} b The byte to insert.
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*/
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bitjs.io.ByteBuffer.prototype.insertByte = function(b) {
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bitjs.io.ByteBuffer.prototype.insertByte = function(b) {
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// TODO: throw if byte is invalid?
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this.data[this.ptr++] = b;
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};
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};
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/**
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/**
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* @param {Array.<number>|Uint8Array|Int8Array} bytes The bytes to insert.
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*/
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bitjs.io.ByteBuffer.prototype.insertBytes = function(bytes) {
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bitjs.io.ByteBuffer.prototype.insertBytes = function(bytes) {
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// TODO: throw if bytes is invalid?
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this.data.set(bytes, this.ptr);
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this.ptr += bytes.length;
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};
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};
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/**
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/**
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* Writes an unsigned number into the next n bytes. If the number is too large
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* to fit into n bytes or is negative, an error is thrown.
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* @param {number} num The unsigned number to write.
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* @param {number} numBytes The number of bytes to write the number into.
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*/
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bitjs.io.ByteBuffer.prototype.writeNumber = function(num, numBytes) {
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bitjs.io.ByteBuffer.prototype.writeNumber = function(num, numBytes) {
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if (numBytes < 1) {
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throw 'Trying to write into too few bytes: ' + numBytes;
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}
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@ -436,16 +436,16 @@ bitjs.io.ByteBuffer.prototype.writeNumber = function(num, numBytes) {
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}
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this.insertBytes(bytes);
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};
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};
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|
/**
|
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|
|
/**
|
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|
* Writes a signed number into the next n bytes. If the number is too large
|
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|
* to fit into n bytes, an error is thrown.
|
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|
|
* @param {number} num The signed number to write.
|
|
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|
|
* @param {number} numBytes The number of bytes to write the number into.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.writeSignedNumber = function(num, numBytes) {
|
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|
|
|
bitjs.io.ByteBuffer.prototype.writeSignedNumber = function(num, numBytes) {
|
|
|
|
|
if (numBytes < 1) {
|
|
|
|
|
throw 'Trying to write into too few bytes: ' + numBytes;
|
|
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|
|
}
|
|
|
|
@ -464,13 +464,13 @@ bitjs.io.ByteBuffer.prototype.writeSignedNumber = function(num, numBytes) {
|
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|
|
}
|
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|
|
|
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|
|
this.insertBytes(bytes);
|
|
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|
|
};
|
|
|
|
|
};
|
|
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|
|
/**
|
|
|
|
|
/**
|
|
|
|
|
* @param {string} str The ASCII string to write.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.writeASCIIString = function(str) {
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.writeASCIIString = function(str) {
|
|
|
|
|
for (var i = 0; i < str.length; ++i) {
|
|
|
|
|
var curByte = str.charCodeAt(i);
|
|
|
|
|
if (curByte < 0 || curByte > 255) {
|
|
|
|
@ -478,6 +478,5 @@ bitjs.io.ByteBuffer.prototype.writeASCIIString = function(str) {
|
|
|
|
|
}
|
|
|
|
|
this.insertByte(curByte);
|
|
|
|
|
}
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
};
|
|
|
|
|
})();
|
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|