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Push — master ( 567ae9...db344a )
by Rafael S.
01:53
created

integer.js ➔ setUp   A

Complexity

Conditions 4
Paths 8

Size

Total Lines 21
Code Lines 12

Duplication

Lines 0
Ratio 0 %

Importance

Changes 0
Metric Value
cc 4
eloc 12
nc 8
nop 1
dl 0
loc 21
rs 9.8
c 0
b 0
f 0
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/*
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 * Copyright (c) 2017-2018 Rafael da Silva Rocha.
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 *
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 * Permission is hereby granted, free of charge, to any person obtaining
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 * a copy of this software and associated documentation files (the
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 * "Software"), to deal in the Software without restriction, including
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 * without limitation the rights to use, copy, modify, merge, publish,
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 * distribute, sublicense, and/or sell copies of the Software, and to
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 * permit persons to whom the Software is furnished to do so, subject to
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 * the following conditions:
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 *
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 * The above copyright notice and this permission notice shall be
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 * included in all copies or substantial portions of the Software.
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 *
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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 *
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 */
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/**
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 * @fileoverview Pack and unpack two's complement ints and unsigned ints.
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 * @see https://github.com/rochars/byte-data
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 */
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/**
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 * A class to pack and unpack two's complement ints and unsigned ints.
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 */
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export default class Integer {
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  constructor() {
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    /**
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     * @type {number}
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     */
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    this.offset = 0;
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    /**
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     * @type {number}
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     */
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    this.realOffset_ = 0;
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    /**
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     * @type {number}
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     * @private
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     */
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    this.bits_ = 0;
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    /**
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     * @type {number}
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     * @private
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     */
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    this.lastByteMask_ = 0;
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    /**
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     * @type {number}
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     * @private
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     */
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    this.max_ = 0;
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    /**
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     * @type {number}
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     * @private
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     */
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    this.min_ = 0;
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  }
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  /**
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   * Set up the object to start serializing/deserializing a data type..
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   * @param {!Object} theType The type definition.
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   */
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  setUp(theType) {
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    /**
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     * The max number of bits used by the data.
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     * @type {number}
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     * @private
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     */
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    this.bits_ = theType.bits;
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    // Set the min and max values according to the number of bits
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    /** @type {number} */
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    let max = Math.pow(2, this.bits_);
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    if (theType.signed) {
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      this.max_ = max / 2 -1;
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      this.min_ = -max / 2;
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    } else {
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      this.max_ = max - 1;
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      this.min_ = 0;
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    }
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    this.setLastByteMask_();
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    this.offset = this.bits_ < 8 ? 1 : Math.ceil(this.bits_ / 8);
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    this.realOffset_ = this.bits_ === 64 ? 4 : this.offset;
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  }
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  /**
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   * Read one integer number from a byte buffer.
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   * @param {!Uint8Array} bytes An array of bytes.
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   * @param {number=} i The index to read.
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   * @return {number}
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   */
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  read(bytes, i=0) {
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    let num = 0;
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    for(let x=0; x<this.realOffset_; x++) {
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      num += bytes[i + x] * Math.pow(256, x);
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    }
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    return this.overflow_(this.sign_(num)); 
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  }
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  /**
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   * Write one integer number to a byte buffer.
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   * @param {!Uint8Array} bytes An array of bytes.
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   * @param {number} num The number.
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   * @param {number=} j The index being written in the byte buffer.
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   * @return {number} The next index to write on the byte buffer.
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   * @private
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   */
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  write(bytes, num, j=0) {
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    j = this.writeFirstByte_(bytes, this.overflow_(num), j);
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    for (let i = 2, len = this.realOffset_; i < len; i++, j++) {
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      bytes[j] = Math.floor(num / Math.pow(2, ((i - 1) * 8))) & 255;
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    }
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    if (this.bits_ > 8) {
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      bytes[j] = Math.floor(
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          num / Math.pow(2, ((this.realOffset_ - 1) * 8))) & this.lastByteMask_;
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      j++;
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Complexity Coding Style introduced by Rafael Rocha
You seem to be assigning a new value to the loop variable j here. Please check if this was indeed your intention. Even if it was, consider using another kind of loop instead.
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    }
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    return j;
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  }
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  /**
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   * Sign a number.
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   * @param {number} num The number.
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   * @return {number}
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   * @private
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   */
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  sign_(num) {
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    if (num > this.max_) {
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      num -= (this.max_ * 2) + 2;
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    }
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    return num;
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  }
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  /**
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   * Trows error in case of underflow or overflow.
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   * @param {number} num The number.
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   * @return {number}
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   * @throws {Error} on overflow or underflow.
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   * @private
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   */
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  overflow_(num) {
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    if (num > this.max_) {
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      throw new Error('Overflow.');
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    } else if (num < this.min_) {
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      throw new Error('Underflow.');
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    }
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    return num;
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  }
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  /**
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   * Set the mask that should be used when writing the last byte.
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   * @private
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   */
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  setLastByteMask_() {
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    /** @type {number} */
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    let r = 8 - ((((this.bits_ - 1) | 7) + 1) - this.bits_);
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    this.lastByteMask_ = Math.pow(2, r > 0 ? r : 8) - 1;
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  }
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  /**
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   * Write the first byte of a integer number.
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   * @param {!Uint8Array} bytes An array of bytes.
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   * @param {number} number The number.
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   * @param {number} j The index being written in the byte buffer.
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   * @return {number} The next index to write on the byte buffer.
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   * @private
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   */
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  writeFirstByte_(bytes, number, j) {
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    if (this.bits_ < 8) {
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      bytes[j] = number < 0 ? number + Math.pow(2, this.bits_) : number;
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    } else {
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      bytes[j] = number & 255;
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    }
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    return j + 1;
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  }
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}
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