76 lines
2.2 KiB
JavaScript
76 lines
2.2 KiB
JavaScript
"use strict";
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/**
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* Copyright (c) 2015, Yaacov Zamir <kobi.zamir@gmail.com>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/**
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* Adds Bit Operations to Buffer
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*/
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var addBufferBitOp = function() {
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/**
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* Add set one bit in a Buffer prototype.
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*
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* @param {boolean} value, new state of bit.
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* @param {number} bit, The bit offset.
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* @param {number} offset, the byte offset.
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*/
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Buffer.prototype.writeBit = function(value, bit, offset) {
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var byteOffset = parseInt(bit / 8 + offset);
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var bitOffset = bit % 8;
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var bitMask = 0x1 << bitOffset;
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// get byte from buffer
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var byte = this.readUInt8(byteOffset);
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// set bit on / off
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if (value) {
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byte |= bitMask;
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} else {
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byte &= ~bitMask;
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}
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// set byte to buffer
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this.writeUInt8(byte, byteOffset);
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};
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/**
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* Add get one bit in a Buffer prototype.
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*
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* @param {boolean} bit, The bit offset.
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* @param {number} offset, the byte offset.
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*
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* @return {boolean} the state of the bit.
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*/
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Buffer.prototype.readBit = function(bit, offset) {
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var byteOffset = parseInt(bit / 8 + offset);
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var bitOffset = bit % 8;
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var bitMask = 0x1 << bitOffset;
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// get byte from buffer
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var byte = this.readUInt8(byteOffset);
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// check bit state
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return (byte & bitMask) === bitMask;
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};
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};
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/**
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* Buffer Bit operations.
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*
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* @type {addBufferBitOp}
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*/
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module.exports = addBufferBitOp;
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