integer.js ➔ readBits_ - Code Metrics - Inspection of "Use the same methods to pack/unpack all integers" - rochars/byte-data - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( 56e3cd...262243 )

by Rafael S.

created 2018-07-16 17:10 UTC

integer.js ➔ readBits_ A

↳ Parent: lib/integer.js

Complexity

Conditions	2
Paths	2

Size

Total Lines	10
Code Lines	6

Duplication

Lines	0
Ratio	0 %

Importance

Changes	2
Bugs	0	Features	0

Metric	Value
cc	2
eloc	6
c	2
b	0
f	0
nc	2
nop	2
dl	0
loc	10
rs	10

/*
 * Copyright (c) 2017-2018 Rafael da Silva Rocha.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

/**
 * @fileoverview Pack and unpack two's complement ints and unsigned ints.
 * @see https://github.com/rochars/byte-data
 */

/**
 * A class to pack and unpack two's complement ints and unsigned ints.
 */
export default class Integer {

  /**
   * @param {number} bits Number of bits used by the data.
   * @param {boolean} signed True for signed types.
   * @throws {Error} if the number of bits is smaller than 1 or greater than 64.
   */
  constructor(bits, signed) {
    /**
     * The max number of bits used by the data.
     * @type {number}
     * @private
     */
    this.bits_ = bits;
    /**
     * The number of bytes used by the data.
     * @type {number}
     * @private
     */
    this.offset_ = 0;
    /**
     * The practical number of bits used by the data.
     * @type {number}
     * @private
     */
    this.realBits_ = this.bits_;
    /**
     * The mask to be used in the last byte.
     * @type {number}
     * @private
     */
    this.lastByteMask_ = 255;
    // Set the min and max values according to the number of bits
    /** @type {number} */
    let max = Math.pow(2, this.bits_);
    if (signed) {
      this.max_ = max / 2 -1;
      this.min_ = -max / 2;
    } else {
      this.max_ = max - 1;
      this.min_ = 0;
    }
    this.build_();
  }

  /**
   * Read one integer number from a byte buffer.
   * @param {!Uint8Array} bytes An array of bytes.
   * @param {number=} i The index to read.
   * @return {number}
   */
  read(bytes, i=0) {
    let num = 0;
    for(let x=0; x<this.offset_; x++) {
      num += bytes[i + x] * Math.pow(256, x);
    }
    return this.overflow_(this.sign_(num)); 
  }

  /**
   * Write one integer number to a byte buffer.
   * @param {!Array<number>} bytes An array of bytes.
   * @param {number} num The number.
   * @param {number=} j The index being written in the byte buffer.
   * @return {number} The next index to write on the byte buffer.
   * @private
   */
  write(bytes, num, j=0) {
    j = this.writeFirstByte_(bytes, this.overflow_(num), j);
    for (let i = 2; i < this.offset_; i++, j++) {
      bytes[j] = Math.floor(num / Math.pow(2, ((i - 1) * 8))) & 255;
    }
    if (this.bits_ > 8) {
      bytes[j] = Math.floor(
          num / Math.pow(2, ((this.offset_ - 1) * 8))) & this.lastByteMask_;
      j++;

    }
    return j;
  }

  /**
   * Build the type.
   * @throws {Error} if the number of bits is smaller than 1 or greater than 64.
   * @private
   */
  build_() {
    this.setRealBits_();
    this.setLastByteMask_();
    this.offset_ = this.bits_ < 8 ? 1 : Math.ceil(this.realBits_ / 8);
  }

  /**
   * Sign a number.
   * @param {number} num The number.
   * @return {number}
   * @private
   */
  sign_(num) {
    if (num > this.max_) {
      num -= (this.max_ * 2) + 2;
    }
    return num;
  }

  /**
   * Trows error in case of underflow or overflow.
   * @param {number} num The number.
   * @return {number}
   * @throws {Error} on overflow or underflow.
   * @private
   */
  overflow_(num) {
    if (num > this.max_) {
      throw new Error('Overflow.');
    } else if (num < this.min_) {
      throw new Error('Underflow.');
    }
    return num;
  }

  /**
   * Set the practical bit number for data with bit count different
   * from the standard types (8, 16, 32, 40, 48, 64).
   * @private
   */
  setRealBits_() {
    this.realBits_ = ((this.bits_ - 1) | 7) + 1;
  }

  /**
   * Set the mask that should be used when writing the last byte.
   * @private
   */
  setLastByteMask_() {
    /** @type {number} */
    let r = 8 - (this.realBits_ - this.bits_);
    this.lastByteMask_ = Math.pow(2, r > 0 ? r : 8) - 1;
  }

  /**
   * Write the first byte of a integer number.
   * @param {!Array<number>} bytes An array of bytes.
   * @param {number} number The number.
   * @param {number} j The index being written in the byte buffer.
   * @return {number} The next index to write on the byte buffer.
   * @private
   */
  writeFirstByte_(bytes, number, j) {
    if (this.bits_ < 8) {
      bytes[j] = number < 0 ? number + Math.pow(2, this.bits_) : number;
    } else {
      bytes[j] = number & 255;
    }
    return j + 1;
  }
}


1			/*
2			* Copyright (c) 2017-2018 Rafael da Silva Rocha.
3			*
4			* Permission is hereby granted, free of charge, to any person obtaining
5			* a copy of this software and associated documentation files (the
6			* "Software"), to deal in the Software without restriction, including
7			* without limitation the rights to use, copy, modify, merge, publish,
8			* distribute, sublicense, and/or sell copies of the Software, and to
9			* permit persons to whom the Software is furnished to do so, subject to
10			* the following conditions:
11			*
12			* The above copyright notice and this permission notice shall be
13			* included in all copies or substantial portions of the Software.
14			*
15			* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16			* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17			* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18			* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
19			* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
20			* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
21			* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
22			*
23			*/
24
25			/**
26			* @fileoverview Pack and unpack two's complement ints and unsigned ints.
27			* @see https://github.com/rochars/byte-data
28			*/
29
30			/**
31			* A class to pack and unpack two's complement ints and unsigned ints.
32			*/
33			export default class Integer {
34
35			/**
36			* @param {number} bits Number of bits used by the data.
37			* @param {boolean} signed True for signed types.
38			* @throws {Error} if the number of bits is smaller than 1 or greater than 64.
39			*/
40			constructor(bits, signed) {
41			/**
42			* The max number of bits used by the data.
43			* @type {number}
44			* @private
45			*/
46			this.bits_ = bits;
47			/**
48			* The number of bytes used by the data.
49			* @type {number}
50			* @private
51			*/
52			this.offset_ = 0;
53			/**
54			* The practical number of bits used by the data.
55			* @type {number}
56			* @private
57			*/
58			this.realBits_ = this.bits_;
59			/**
60			* The mask to be used in the last byte.
61			* @type {number}
62			* @private
63			*/
64			this.lastByteMask_ = 255;
65			// Set the min and max values according to the number of bits
66			/** @type {number} */
67			let max = Math.pow(2, this.bits_);
68			if (signed) {
69			this.max_ = max / 2 -1;
70			this.min_ = -max / 2;
71			} else {
72			this.max_ = max - 1;
73			this.min_ = 0;
74			}
75			this.build_();
76			}
77
78			/**
79			* Read one integer number from a byte buffer.
80			* @param {!Uint8Array} bytes An array of bytes.
81			* @param {number=} i The index to read.
82			* @return {number}
83			*/
84			read(bytes, i=0) {
85			let num = 0;
86			for(let x=0; x<this.offset_; x++) {
87			num += bytes[i + x] * Math.pow(256, x);
88			}
89			return this.overflow_(this.sign_(num));
90			}
91
92			/**
93			* Write one integer number to a byte buffer.
94			* @param {!Array<number>} bytes An array of bytes.
95			* @param {number} num The number.
96			* @param {number=} j The index being written in the byte buffer.
97			* @return {number} The next index to write on the byte buffer.
98			* @private
99			*/
100			write(bytes, num, j=0) {
101			j = this.writeFirstByte_(bytes, this.overflow_(num), j);
102			for (let i = 2; i < this.offset_; i++, j++) {
103			bytes[j] = Math.floor(num / Math.pow(2, ((i - 1) * 8))) & 255;
104			}
105			if (this.bits_ > 8) {
106			bytes[j] = Math.floor(
107			num / Math.pow(2, ((this.offset_ - 1) * 8))) & this.lastByteMask_;
108			j++;
			0 ignored issues – show Complexity Coding Style introduced 2018-07-16 17:11 UTC by Report Bug Copy Issue Report 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. Loading history...
109			}
110			return j;
111			}
112
113			/**
114			* Build the type.
115			* @throws {Error} if the number of bits is smaller than 1 or greater than 64.
116			* @private
117			*/
118			build_() {
119			this.setRealBits_();
120			this.setLastByteMask_();
121			this.offset_ = this.bits_ < 8 ? 1 : Math.ceil(this.realBits_ / 8);
122			}
123
124			/**
125			* Sign a number.
126			* @param {number} num The number.
127			* @return {number}
128			* @private
129			*/
130			sign_(num) {
131			if (num > this.max_) {
132			num -= (this.max_ * 2) + 2;
133			}
134			return num;
135			}
136
137			/**
138			* Trows error in case of underflow or overflow.
139			* @param {number} num The number.
140			* @return {number}
141			* @throws {Error} on overflow or underflow.
142			* @private
143			*/
144			overflow_(num) {
145			if (num > this.max_) {
146			throw new Error('Overflow.');
147			} else if (num < this.min_) {
148			throw new Error('Underflow.');
149			}
150			return num;
151			}
152
153			/**
154			* Set the practical bit number for data with bit count different
155			* from the standard types (8, 16, 32, 40, 48, 64).
156			* @private
157			*/
158			setRealBits_() {
159			this.realBits_ = ((this.bits_ - 1) \| 7) + 1;
160			}
161
162			/**
163			* Set the mask that should be used when writing the last byte.
164			* @private
165			*/
166			setLastByteMask_() {
167			/** @type {number} */
168			let r = 8 - (this.realBits_ - this.bits_);
169			this.lastByteMask_ = Math.pow(2, r > 0 ? r : 8) - 1;
170			}
171
172			/**
173			* Write the first byte of a integer number.
174			* @param {!Array<number>} bytes An array of bytes.
175			* @param {number} number The number.
176			* @param {number} j The index being written in the byte buffer.
177			* @return {number} The next index to write on the byte buffer.
178			* @private
179			*/
180			writeFirstByte_(bytes, number, j) {
181			if (this.bits_ < 8) {
182			bytes[j] = number < 0 ? number + Math.pow(2, this.bits_) : number;
183			} else {
184			bytes[j] = number & 255;
185			}
186			return j + 1;
187			}
188			}
189

rochars / byte-data

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integer.js ➔ readBits_ A

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