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@ -14,470 +14,469 @@ 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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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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/**
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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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* @param {boolean} rtl Whether the stream reads bits from the byte starting
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* from bit 7 to 0 (true) or bit 0 to 7 (false).
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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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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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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.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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* byte0 byte1 byte2 byte3
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* 7......0 | 7......0 | 7......0 | 7......0
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*
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* The bit pointer starts at bit0 of byte0 and moves left until it reaches
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* bit7 of byte0, then jumps to bit0 of byte1, etc.
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* @param {number} n The number of bits to peek.
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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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if (n <= 0 || typeof n != typeof 1) {
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return 0;
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}
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var movePointers = movePointers || false,
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bytePtr = this.bytePtr,
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bitPtr = this.bitPtr,
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result = 0,
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bitsIn = 0,
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bytes = this.bytes;
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// keep going until we have no more bits left to peek at
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// TODO: Consider putting all bits from bytes we will need into a variable and then
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// shifting/masking it to just extract the bits we want.
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// This could be considerably faster when reading more than 3 or 4 bits at a time.
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while (n > 0) {
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if (bytePtr >= bytes.length) {
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throw "Error! Overflowed the bit stream! n=" + n + ", bytePtr=" + bytePtr + ", bytes.length=" +
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bytes.length + ", bitPtr=" + bitPtr;
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return -1;
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}
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var numBitsLeftInThisByte = (8 - bitPtr);
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if (n >= numBitsLeftInThisByte) {
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var mask = (BITMASK[numBitsLeftInThisByte] << bitPtr);
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result |= (((bytes[bytePtr] & mask) >> bitPtr) << bitsIn);
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bytePtr++;
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bitPtr = 0;
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bitsIn += numBitsLeftInThisByte;
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n -= numBitsLeftInThisByte;
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}
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else {
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var mask = (BITMASK[n] << bitPtr);
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result |= (((bytes[bytePtr] & mask) >> bitPtr) << bitsIn);
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bitPtr += n;
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bitsIn += n;
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n = 0;
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}
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}
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if (movePointers) {
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this.bitPtr = bitPtr;
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this.bytePtr = bytePtr;
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}
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return result;
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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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* The bit pointer starts at bit7 of byte0 and moves right until it reaches
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* bit0 of byte0, then goes to bit7 of byte1, etc.
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* @param {number} n The number of bits to peek.
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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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if (n <= 0 || typeof n != typeof 1) {
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return 0;
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}
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var movePointers = movePointers || false,
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bytePtr = this.bytePtr,
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bitPtr = this.bitPtr,
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result = 0,
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bytes = this.bytes;
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// keep going until we have no more bits left to peek at
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// TODO: Consider putting all bits from bytes we will need into a variable and then
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// shifting/masking it to just extract the bits we want.
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// This could be considerably faster when reading more than 3 or 4 bits at a time.
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while (n > 0) {
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if (bytePtr >= bytes.length) {
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throw "Error! Overflowed the bit stream! n=" + n + ", bytePtr=" + bytePtr + ", bytes.length=" +
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bytes.length + ", bitPtr=" + bitPtr;
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return -1;
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}
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var numBitsLeftInThisByte = (8 - bitPtr);
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if (n >= numBitsLeftInThisByte) {
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result <<= numBitsLeftInThisByte;
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result |= (BITMASK[numBitsLeftInThisByte] & bytes[bytePtr]);
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bytePtr++;
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bitPtr = 0;
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n -= numBitsLeftInThisByte;
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}
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else {
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result <<= n;
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result |= ((bytes[bytePtr] & (BITMASK[n] << (8 - n - bitPtr))) >> (8 - n - bitPtr));
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bitPtr += n;
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n = 0;
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}
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}
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if (movePointers) {
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this.bitPtr = bitPtr;
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this.bytePtr = bytePtr;
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}
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return result;
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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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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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* 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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return this.peekBits(n, true);
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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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* @param {number} n The number of bytes to peek.
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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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if (n <= 0 || typeof n != typeof 1) {
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return 0;
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}
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// from http://tools.ietf.org/html/rfc1951#page-11
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// "Any bits of input up to the next byte boundary are ignored."
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while (this.bitPtr != 0) {
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this.readBits(1);
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}
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var movePointers = movePointers || false;
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var bytePtr = this.bytePtr,
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bitPtr = this.bitPtr;
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var result = this.bytes.subarray(bytePtr, bytePtr + n);
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if (movePointers) {
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this.bytePtr += n;
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}
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return result;
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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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return this.peekBytes(n, true);
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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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* @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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* @constructor
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*/
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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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* 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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// 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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var result = 0;
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// read from last byte to first byte and roll them in
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var curByte = this.ptr + n - 1;
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while (curByte >= this.ptr) {
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result <<= 8;
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result |= this.bytes[curByte];
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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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* 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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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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* 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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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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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.
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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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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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* 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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if (n <= 0 || typeof n != typeof 1) {
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return null;
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}
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var result = this.bytes.subarray(this.ptr, this.ptr + n);
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if (movePointers) {
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this.ptr += n;
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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.
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* @return {Uint8Array} The subarray.
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*/
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|
bitjs.io.ByteStream.prototype.readBytes = function(n) {
|
|
|
|
|
return this.peekBytes(n, true);
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Peeks at the next n bytes as a string but does not advance the pointer.
|
|
|
|
|
* @param {number} n The number of bytes to peek at.
|
|
|
|
|
* @return {string} The next n bytes as a string.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.peekString = function(n) {
|
|
|
|
|
if (n <= 0 || typeof n != typeof 1) {
|
|
|
|
|
return "";
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var result = "";
|
|
|
|
|
for (var p = this.ptr, end = this.ptr + n; p < end; ++p) {
|
|
|
|
|
result += String.fromCharCode(this.bytes[p]);
|
|
|
|
|
}
|
|
|
|
|
return result;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Returns the next n bytes as an ASCII string and advances the stream pointer
|
|
|
|
|
* n bytes.
|
|
|
|
|
* @param {number} n The number of bytes to read.
|
|
|
|
|
* @return {string} The next n bytes as a string.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.readString = function(n) {
|
|
|
|
|
var strToReturn = this.peekString(n);
|
|
|
|
|
this.ptr += n;
|
|
|
|
|
return strToReturn;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* A write-only Byte buffer which uses a Uint8 Typed Array as a backing store.
|
|
|
|
|
* @param {number} numBytes The number of bytes to allocate.
|
|
|
|
|
* @constructor
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer = function(numBytes) {
|
|
|
|
|
if (typeof numBytes != typeof 1 || numBytes <= 0) {
|
|
|
|
|
throw "Error! ByteBuffer initialized with '" + numBytes + "'";
|
|
|
|
|
}
|
|
|
|
|
this.data = new Uint8Array(numBytes);
|
|
|
|
|
this.ptr = 0;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* @param {number} b The byte to insert.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.insertByte = function(b) {
|
|
|
|
|
// TODO: throw if byte is invalid?
|
|
|
|
|
this.data[this.ptr++] = b;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* @param {Array.<number>|Uint8Array|Int8Array} bytes The bytes to insert.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.insertBytes = function(bytes) {
|
|
|
|
|
// TODO: throw if bytes is invalid?
|
|
|
|
|
this.data.set(bytes, this.ptr);
|
|
|
|
|
this.ptr += bytes.length;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Writes an unsigned number into the next n bytes. If the number is too large
|
|
|
|
|
* to fit into n bytes or is negative, an error is thrown.
|
|
|
|
|
* @param {number} num The unsigned number to write.
|
|
|
|
|
* @param {number} numBytes The number of bytes to write the number into.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.writeNumber = function(num, numBytes) {
|
|
|
|
|
if (numBytes < 1) {
|
|
|
|
|
throw 'Trying to write into too few bytes: ' + numBytes;
|
|
|
|
|
}
|
|
|
|
|
if (num < 0) {
|
|
|
|
|
throw 'Trying to write a negative number (' + num +
|
|
|
|
|
') as an unsigned number to an ArrayBuffer';
|
|
|
|
|
}
|
|
|
|
|
if (num > (Math.pow(2, numBytes * 8) - 1)) {
|
|
|
|
|
throw 'Trying to write ' + num + ' into only ' + numBytes + ' bytes';
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// Roll 8-bits at a time into an array of bytes.
|
|
|
|
|
var bytes = [];
|
|
|
|
|
while (numBytes-- > 0) {
|
|
|
|
|
var eightBits = num & 255;
|
|
|
|
|
bytes.push(eightBits);
|
|
|
|
|
num >>= 8;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
this.insertBytes(bytes);
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Writes a signed number into the next n bytes. If the number is too large
|
|
|
|
|
* to fit into n bytes, an error is thrown.
|
|
|
|
|
* @param {number} num The signed number to write.
|
|
|
|
|
* @param {number} numBytes The number of bytes to write the number into.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.writeSignedNumber = function(num, numBytes) {
|
|
|
|
|
if (numBytes < 1) {
|
|
|
|
|
throw 'Trying to write into too few bytes: ' + numBytes;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var HALF = Math.pow(2, (numBytes * 8) - 1);
|
|
|
|
|
if (num >= HALF || num < -HALF) {
|
|
|
|
|
throw 'Trying to write ' + num + ' into only ' + numBytes + ' bytes';
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// Roll 8-bits at a time into an array of bytes.
|
|
|
|
|
var bytes = [];
|
|
|
|
|
while (numBytes-- > 0) {
|
|
|
|
|
var eightBits = num & 255;
|
|
|
|
|
bytes.push(eightBits);
|
|
|
|
|
num >>= 8;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
this.insertBytes(bytes);
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* @param {string} str The ASCII string to write.
|
|
|
|
|
*/
|
|
|
|
|
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) {
|
|
|
|
|
throw 'Trying to write a non-ASCII string!';
|
|
|
|
|
}
|
|
|
|
|
this.insertByte(curByte);
|
|
|
|
|
}
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
// mask for getting the Nth bit (zero-based)
|
|
|
|
|
bitjs.BIT = [ 0x01, 0x02, 0x04, 0x08,
|
|
|
|
|
0x10, 0x20, 0x40, 0x80,
|
|
|
|
|
0x100, 0x200, 0x400, 0x800,
|
|
|
|
|
0x1000, 0x2000, 0x4000, 0x8000];
|
|
|
|
|
|
|
|
|
|
// mask for getting N number of bits (0-8)
|
|
|
|
|
var BITMASK = [0, 0x01, 0x03, 0x07, 0x0F, 0x1F, 0x3F, 0x7F, 0xFF ];
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* This bit stream peeks and consumes bits out of a binary stream.
|
|
|
|
|
*
|
|
|
|
|
* @param {ArrayBuffer} ab An ArrayBuffer object or a Uint8Array.
|
|
|
|
|
* @param {boolean} rtl Whether the stream reads bits from the byte starting
|
|
|
|
|
* from bit 7 to 0 (true) or bit 0 to 7 (false).
|
|
|
|
|
* @param {Number} opt_offset The offset into the ArrayBuffer
|
|
|
|
|
* @param {Number} opt_length The length of this BitStream
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.BitStream = function(ab, rtl, opt_offset, opt_length) {
|
|
|
|
|
if (!ab || !ab.toString || ab.toString() !== "[object ArrayBuffer]") {
|
|
|
|
|
throw "Error! BitArray constructed with an invalid ArrayBuffer object";
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var offset = opt_offset || 0;
|
|
|
|
|
var length = opt_length || ab.byteLength;
|
|
|
|
|
this.bytes = new Uint8Array(ab, offset, length);
|
|
|
|
|
this.bytePtr = 0; // tracks which byte we are on
|
|
|
|
|
this.bitPtr = 0; // tracks which bit we are on (can have values 0 through 7)
|
|
|
|
|
this.peekBits = rtl ? this.peekBits_rtl : this.peekBits_ltr;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* byte0 byte1 byte2 byte3
|
|
|
|
|
* 7......0 | 7......0 | 7......0 | 7......0
|
|
|
|
|
*
|
|
|
|
|
* The bit pointer starts at bit0 of byte0 and moves left until it reaches
|
|
|
|
|
* bit7 of byte0, then jumps to bit0 of byte1, etc.
|
|
|
|
|
* @param {number} n The number of bits to peek.
|
|
|
|
|
* @param {boolean=} movePointers Whether to move the pointer, defaults false.
|
|
|
|
|
* @return {number} The peeked bits, as an unsigned number.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.BitStream.prototype.peekBits_ltr = function(n, movePointers) {
|
|
|
|
|
if (n <= 0 || typeof n != typeof 1) {
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var movePointers = movePointers || false,
|
|
|
|
|
bytePtr = this.bytePtr,
|
|
|
|
|
bitPtr = this.bitPtr,
|
|
|
|
|
result = 0,
|
|
|
|
|
bitsIn = 0,
|
|
|
|
|
bytes = this.bytes;
|
|
|
|
|
|
|
|
|
|
// keep going until we have no more bits left to peek at
|
|
|
|
|
// TODO: Consider putting all bits from bytes we will need into a variable and then
|
|
|
|
|
// shifting/masking it to just extract the bits we want.
|
|
|
|
|
// This could be considerably faster when reading more than 3 or 4 bits at a time.
|
|
|
|
|
while (n > 0) {
|
|
|
|
|
if (bytePtr >= bytes.length) {
|
|
|
|
|
throw "Error! Overflowed the bit stream! n=" + n + ", bytePtr=" + bytePtr + ", bytes.length=" +
|
|
|
|
|
bytes.length + ", bitPtr=" + bitPtr;
|
|
|
|
|
return -1;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var numBitsLeftInThisByte = (8 - bitPtr);
|
|
|
|
|
if (n >= numBitsLeftInThisByte) {
|
|
|
|
|
var mask = (BITMASK[numBitsLeftInThisByte] << bitPtr);
|
|
|
|
|
result |= (((bytes[bytePtr] & mask) >> bitPtr) << bitsIn);
|
|
|
|
|
|
|
|
|
|
bytePtr++;
|
|
|
|
|
bitPtr = 0;
|
|
|
|
|
bitsIn += numBitsLeftInThisByte;
|
|
|
|
|
n -= numBitsLeftInThisByte;
|
|
|
|
|
}
|
|
|
|
|
else {
|
|
|
|
|
var mask = (BITMASK[n] << bitPtr);
|
|
|
|
|
result |= (((bytes[bytePtr] & mask) >> bitPtr) << bitsIn);
|
|
|
|
|
|
|
|
|
|
bitPtr += n;
|
|
|
|
|
bitsIn += n;
|
|
|
|
|
n = 0;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
if (movePointers) {
|
|
|
|
|
this.bitPtr = bitPtr;
|
|
|
|
|
this.bytePtr = bytePtr;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return result;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* byte0 byte1 byte2 byte3
|
|
|
|
|
* 7......0 | 7......0 | 7......0 | 7......0
|
|
|
|
|
*
|
|
|
|
|
* The bit pointer starts at bit7 of byte0 and moves right until it reaches
|
|
|
|
|
* bit0 of byte0, then goes to bit7 of byte1, etc.
|
|
|
|
|
* @param {number} n The number of bits to peek.
|
|
|
|
|
* @param {boolean=} movePointers Whether to move the pointer, defaults false.
|
|
|
|
|
* @return {number} The peeked bits, as an unsigned number.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.BitStream.prototype.peekBits_rtl = function(n, movePointers) {
|
|
|
|
|
if (n <= 0 || typeof n != typeof 1) {
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var movePointers = movePointers || false,
|
|
|
|
|
bytePtr = this.bytePtr,
|
|
|
|
|
bitPtr = this.bitPtr,
|
|
|
|
|
result = 0,
|
|
|
|
|
bytes = this.bytes;
|
|
|
|
|
|
|
|
|
|
// keep going until we have no more bits left to peek at
|
|
|
|
|
// TODO: Consider putting all bits from bytes we will need into a variable and then
|
|
|
|
|
// shifting/masking it to just extract the bits we want.
|
|
|
|
|
// This could be considerably faster when reading more than 3 or 4 bits at a time.
|
|
|
|
|
while (n > 0) {
|
|
|
|
|
|
|
|
|
|
if (bytePtr >= bytes.length) {
|
|
|
|
|
throw "Error! Overflowed the bit stream! n=" + n + ", bytePtr=" + bytePtr + ", bytes.length=" +
|
|
|
|
|
bytes.length + ", bitPtr=" + bitPtr;
|
|
|
|
|
return -1;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var numBitsLeftInThisByte = (8 - bitPtr);
|
|
|
|
|
if (n >= numBitsLeftInThisByte) {
|
|
|
|
|
result <<= numBitsLeftInThisByte;
|
|
|
|
|
result |= (BITMASK[numBitsLeftInThisByte] & bytes[bytePtr]);
|
|
|
|
|
bytePtr++;
|
|
|
|
|
bitPtr = 0;
|
|
|
|
|
n -= numBitsLeftInThisByte;
|
|
|
|
|
}
|
|
|
|
|
else {
|
|
|
|
|
result <<= n;
|
|
|
|
|
result |= ((bytes[bytePtr] & (BITMASK[n] << (8 - n - bitPtr))) >> (8 - n - bitPtr));
|
|
|
|
|
|
|
|
|
|
bitPtr += n;
|
|
|
|
|
n = 0;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
if (movePointers) {
|
|
|
|
|
this.bitPtr = bitPtr;
|
|
|
|
|
this.bytePtr = bytePtr;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return result;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Some voodoo magic.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.BitStream.prototype.getBits = function() {
|
|
|
|
|
return (((((this.bytes[this.bytePtr] & 0xff) << 16) +
|
|
|
|
|
((this.bytes[this.bytePtr+1] & 0xff) << 8) +
|
|
|
|
|
((this.bytes[this.bytePtr+2] & 0xff))) >>> (8-this.bitPtr)) & 0xffff);
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Reads n bits out of the stream, consuming them (moving the bit pointer).
|
|
|
|
|
* @param {number} n The number of bits to read.
|
|
|
|
|
* @return {number} The read bits, as an unsigned number.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.BitStream.prototype.readBits = function(n) {
|
|
|
|
|
return this.peekBits(n, true);
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* This returns n bytes as a sub-array, advancing the pointer if movePointers
|
|
|
|
|
* is true. Only use this for uncompressed blocks as this throws away remaining
|
|
|
|
|
* bits in the current byte.
|
|
|
|
|
* @param {number} n The number of bytes to peek.
|
|
|
|
|
* @param {boolean=} movePointers Whether to move the pointer, defaults false.
|
|
|
|
|
* @return {Uint8Array} The subarray.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.BitStream.prototype.peekBytes = function(n, movePointers) {
|
|
|
|
|
if (n <= 0 || typeof n != typeof 1) {
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// from http://tools.ietf.org/html/rfc1951#page-11
|
|
|
|
|
// "Any bits of input up to the next byte boundary are ignored."
|
|
|
|
|
while (this.bitPtr != 0) {
|
|
|
|
|
this.readBits(1);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var movePointers = movePointers || false;
|
|
|
|
|
var bytePtr = this.bytePtr,
|
|
|
|
|
bitPtr = this.bitPtr;
|
|
|
|
|
|
|
|
|
|
var result = this.bytes.subarray(bytePtr, bytePtr + n);
|
|
|
|
|
|
|
|
|
|
if (movePointers) {
|
|
|
|
|
this.bytePtr += n;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return result;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* @param {number} n The number of bytes to read.
|
|
|
|
|
* @return {Uint8Array} The subarray.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.BitStream.prototype.readBytes = function(n) {
|
|
|
|
|
return this.peekBytes(n, true);
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* This object allows you to peek and consume bytes as numbers and strings
|
|
|
|
|
* out of an ArrayBuffer. In this buffer, everything must be byte-aligned.
|
|
|
|
|
*
|
|
|
|
|
* @param {ArrayBuffer} ab The ArrayBuffer object.
|
|
|
|
|
* @param {number=} opt_offset The offset into the ArrayBuffer
|
|
|
|
|
* @param {number=} opt_length The length of this BitStream
|
|
|
|
|
* @constructor
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream = function(ab, opt_offset, opt_length) {
|
|
|
|
|
var offset = opt_offset || 0;
|
|
|
|
|
var length = opt_length || ab.byteLength;
|
|
|
|
|
this.bytes = new Uint8Array(ab, offset, length);
|
|
|
|
|
this.ptr = 0;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Peeks at the next n bytes as an unsigned number but does not advance the
|
|
|
|
|
* pointer
|
|
|
|
|
* TODO: This apparently cannot read more than 4 bytes as a number?
|
|
|
|
|
* @param {number} n The number of bytes to peek at.
|
|
|
|
|
* @return {number} The n bytes interpreted as an unsigned number.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.peekNumber = function(n) {
|
|
|
|
|
// TODO: return error if n would go past the end of the stream?
|
|
|
|
|
if (n <= 0 || typeof n != typeof 1)
|
|
|
|
|
return -1;
|
|
|
|
|
|
|
|
|
|
var result = 0;
|
|
|
|
|
// read from last byte to first byte and roll them in
|
|
|
|
|
var curByte = this.ptr + n - 1;
|
|
|
|
|
while (curByte >= this.ptr) {
|
|
|
|
|
result <<= 8;
|
|
|
|
|
result |= this.bytes[curByte];
|
|
|
|
|
--curByte;
|
|
|
|
|
}
|
|
|
|
|
return result;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Returns the next n bytes as an unsigned number (or -1 on error)
|
|
|
|
|
* and advances the stream pointer n bytes.
|
|
|
|
|
* @param {number} n The number of bytes to read.
|
|
|
|
|
* @return {number} The n bytes interpreted as an unsigned number.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.readNumber = function(n) {
|
|
|
|
|
var num = this.peekNumber( n );
|
|
|
|
|
this.ptr += n;
|
|
|
|
|
return num;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Returns the next n bytes as a signed number but does not advance the
|
|
|
|
|
* pointer.
|
|
|
|
|
* @param {number} n The number of bytes to read.
|
|
|
|
|
* @return {number} The bytes interpreted as a signed number.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.peekSignedNumber = function(n) {
|
|
|
|
|
var num = this.peekNumber(n);
|
|
|
|
|
var HALF = Math.pow(2, (n * 8) - 1);
|
|
|
|
|
var FULL = HALF * 2;
|
|
|
|
|
|
|
|
|
|
if (num >= HALF) num -= FULL;
|
|
|
|
|
|
|
|
|
|
return num;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Returns the next n bytes as a signed number and advances the stream pointer.
|
|
|
|
|
* @param {number} n The number of bytes to read.
|
|
|
|
|
* @return {number} The bytes interpreted as a signed number.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.readSignedNumber = function(n) {
|
|
|
|
|
var num = this.peekSignedNumber(n);
|
|
|
|
|
this.ptr += n;
|
|
|
|
|
return num;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* This returns n bytes as a sub-array, advancing the pointer if movePointers
|
|
|
|
|
* is true.
|
|
|
|
|
* @param {number} n The number of bytes to read.
|
|
|
|
|
* @param {boolean} movePointers Whether to move the pointers.
|
|
|
|
|
* @return {Uint8Array} The subarray.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.peekBytes = function(n, movePointers) {
|
|
|
|
|
if (n <= 0 || typeof n != typeof 1) {
|
|
|
|
|
return null;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var result = this.bytes.subarray(this.ptr, this.ptr + n);
|
|
|
|
|
|
|
|
|
|
if (movePointers) {
|
|
|
|
|
this.ptr += n;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return result;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Reads the next n bytes as a sub-array.
|
|
|
|
|
* @param {number} n The number of bytes to read.
|
|
|
|
|
* @return {Uint8Array} The subarray.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.readBytes = function(n) {
|
|
|
|
|
return this.peekBytes(n, true);
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Peeks at the next n bytes as a string but does not advance the pointer.
|
|
|
|
|
* @param {number} n The number of bytes to peek at.
|
|
|
|
|
* @return {string} The next n bytes as a string.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.peekString = function(n) {
|
|
|
|
|
if (n <= 0 || typeof n != typeof 1) {
|
|
|
|
|
return "";
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var result = "";
|
|
|
|
|
for (var p = this.ptr, end = this.ptr + n; p < end; ++p) {
|
|
|
|
|
result += String.fromCharCode(this.bytes[p]);
|
|
|
|
|
}
|
|
|
|
|
return result;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Returns the next n bytes as an ASCII string and advances the stream pointer
|
|
|
|
|
* n bytes.
|
|
|
|
|
* @param {number} n The number of bytes to read.
|
|
|
|
|
* @return {string} The next n bytes as a string.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteStream.prototype.readString = function(n) {
|
|
|
|
|
var strToReturn = this.peekString(n);
|
|
|
|
|
this.ptr += n;
|
|
|
|
|
return strToReturn;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* A write-only Byte buffer which uses a Uint8 Typed Array as a backing store.
|
|
|
|
|
* @param {number} numBytes The number of bytes to allocate.
|
|
|
|
|
* @constructor
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer = function(numBytes) {
|
|
|
|
|
if (typeof numBytes != typeof 1 || numBytes <= 0) {
|
|
|
|
|
throw "Error! ByteBuffer initialized with '" + numBytes + "'";
|
|
|
|
|
}
|
|
|
|
|
this.data = new Uint8Array(numBytes);
|
|
|
|
|
this.ptr = 0;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* @param {number} b The byte to insert.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.insertByte = function(b) {
|
|
|
|
|
// TODO: throw if byte is invalid?
|
|
|
|
|
this.data[this.ptr++] = b;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* @param {Array.<number>|Uint8Array|Int8Array} bytes The bytes to insert.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.insertBytes = function(bytes) {
|
|
|
|
|
// TODO: throw if bytes is invalid?
|
|
|
|
|
this.data.set(bytes, this.ptr);
|
|
|
|
|
this.ptr += bytes.length;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Writes an unsigned number into the next n bytes. If the number is too large
|
|
|
|
|
* to fit into n bytes or is negative, an error is thrown.
|
|
|
|
|
* @param {number} num The unsigned number to write.
|
|
|
|
|
* @param {number} numBytes The number of bytes to write the number into.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.writeNumber = function(num, numBytes) {
|
|
|
|
|
if (numBytes < 1) {
|
|
|
|
|
throw 'Trying to write into too few bytes: ' + numBytes;
|
|
|
|
|
}
|
|
|
|
|
if (num < 0) {
|
|
|
|
|
throw 'Trying to write a negative number (' + num +
|
|
|
|
|
') as an unsigned number to an ArrayBuffer';
|
|
|
|
|
}
|
|
|
|
|
if (num > (Math.pow(2, numBytes * 8) - 1)) {
|
|
|
|
|
throw 'Trying to write ' + num + ' into only ' + numBytes + ' bytes';
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// Roll 8-bits at a time into an array of bytes.
|
|
|
|
|
var bytes = [];
|
|
|
|
|
while (numBytes-- > 0) {
|
|
|
|
|
var eightBits = num & 255;
|
|
|
|
|
bytes.push(eightBits);
|
|
|
|
|
num >>= 8;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
this.insertBytes(bytes);
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Writes a signed number into the next n bytes. If the number is too large
|
|
|
|
|
* to fit into n bytes, an error is thrown.
|
|
|
|
|
* @param {number} num The signed number to write.
|
|
|
|
|
* @param {number} numBytes The number of bytes to write the number into.
|
|
|
|
|
*/
|
|
|
|
|
bitjs.io.ByteBuffer.prototype.writeSignedNumber = function(num, numBytes) {
|
|
|
|
|
if (numBytes < 1) {
|
|
|
|
|
throw 'Trying to write into too few bytes: ' + numBytes;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
var HALF = Math.pow(2, (numBytes * 8) - 1);
|
|
|
|
|
if (num >= HALF || num < -HALF) {
|
|
|
|
|
throw 'Trying to write ' + num + ' into only ' + numBytes + ' bytes';
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// Roll 8-bits at a time into an array of bytes.
|
|
|
|
|
var bytes = [];
|
|
|
|
|
while (numBytes-- > 0) {
|
|
|
|
|
var eightBits = num & 255;
|
|
|
|
|
bytes.push(eightBits);
|
|
|
|
|
num >>= 8;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
this.insertBytes(bytes);
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* @param {string} str The ASCII string to write.
|
|
|
|
|
*/
|
|
|
|
|
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) {
|
|
|
|
|
throw 'Trying to write a non-ASCII string!';
|
|
|
|
|
}
|
|
|
|
|
this.insertByte(curByte);
|
|
|
|
|
}
|
|
|
|
|
};
|
|
|
|
|
})();
|
|
|
|
|
|
OzzieIsaacs
7 years ago