integer.js ➔ setLastByteMask_ - Code Metrics - Inspection of "Remove unnecessary property initialization in setU..." - rochars/byte-data - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( f2cb58...56e3cd )

by Rafael S.

created 2018-07-16 17:09 UTC

integer.js ➔ setLastByteMask_ A

↳ Parent: lib/integer.js

Complexity

Conditions	2
Paths	2

Size

Total Lines	5
Code Lines	3

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	2
eloc	3
c	1
b	0
f	0
nc	2
nop	0
dl	0
loc	5
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;
    /** @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) {
    /** @type {number} */
    let num = 0;
    /** @type {number} */
    let x = this.offset_ - 1;
    for (; x > 0; x--) {
      num = (bytes[x + i] << x * 8) | num;
    }
    num = (bytes[i] | num) >>> 0;
    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.
   */
  write(bytes, num, j=0) {
    bytes[j] = this.overflow_(num) & 255;
    j++;
    for (let i = 2; i <= this.offset_; i++, j++) {
      bytes[j] = Math.floor(num / Math.pow(2, ((i - 1) * 8))) & 255;
    }
    return j;
  }

  /**
   * 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
   */
  writeEsoteric_(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;
  }

  /**
   * Read a integer number from a byte buffer by turning int bytes
   * to a string of bits. Used for data with more than 32 bits.
   * @param {!Uint8Array} bytes An array of bytes.
   * @param {number=} i The index to read.
   * @return {number}
   * @private
   */
  readBits_(bytes, i=0) {
    /** @type {string} */
    let binary = '';
    for (let j = 0; j < this.offset_; j++) {
      /** @type {string} */
      let bits = bytes[i + j].toString(2);
      binary = new Array(9 - bits.length).join('0') + bits + binary;
    }
    return this.overflow_(this.sign_(parseInt(binary, 2)));
  }

  /**
   * 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);
    if ((this.realBits_ != this.bits_) || this.bits_ < 8 || this.bits_ > 32) {
      this.write = this.writeEsoteric_;
      this.read = this.readBits_;
    }
  }

  /**
   * 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			/** @type {number} */
66			let max = Math.pow(2, this.bits_);
67			if (signed) {
68			this.max_ = max / 2 -1;
69			this.min_ = -max / 2;
70			} else {
71			this.max_ = max - 1;
72			this.min_ = 0;
73			}
74			this.build_();
75			}
76
77			/**
78			* Read one integer number from a byte buffer.
79			* @param {!Uint8Array} bytes An array of bytes.
80			* @param {number=} i The index to read.
81			* @return {number}
82			*/
83			read(bytes, i=0) {
84			/** @type {number} */
85			let num = 0;
86			/** @type {number} */
87			let x = this.offset_ - 1;
88			for (; x > 0; x--) {
89			num = (bytes[x + i] << x * 8) \| num;
90			}
91			num = (bytes[i] \| num) >>> 0;
92			return this.overflow_(this.sign_(num));
93			}
94
95			/**
96			* Write one integer number to a byte buffer.
97			* @param {!Array<number>} bytes An array of bytes.
98			* @param {number} num The number.
99			* @param {number=} j The index being written in the byte buffer.
100			* @return {number} The next index to write on the byte buffer.
101			*/
102			write(bytes, num, j=0) {
103			bytes[j] = this.overflow_(num) & 255;
104			j++;
105			for (let i = 2; i <= this.offset_; i++, j++) {
106			bytes[j] = Math.floor(num / Math.pow(2, ((i - 1) * 8))) & 255;
107			}
108			return j;
109			}
110
111			/**
112			* Write one integer number to a byte buffer.
113			* @param {!Array<number>} bytes An array of bytes.
114			* @param {number} num The number.
115			* @param {number=} j The index being written in the byte buffer.
116			* @return {number} The next index to write on the byte buffer.
117			* @private
118			*/
119			writeEsoteric_(bytes, num, j=0) {
120			j = this.writeFirstByte_(bytes, this.overflow_(num), j);
121			for (let i = 2; i < this.offset_; i++, j++) {
122			bytes[j] = Math.floor(num / Math.pow(2, ((i - 1) * 8))) & 255;
123			}
124			if (this.bits_ > 8) {
125			bytes[j] = Math.floor(
126			num / Math.pow(2, ((this.offset_ - 1) * 8))) & this.lastByteMask_;
127			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...
128			}
129			return j;
130			}
131
132			/**
133			* Read a integer number from a byte buffer by turning int bytes
134			* to a string of bits. Used for data with more than 32 bits.
135			* @param {!Uint8Array} bytes An array of bytes.
136			* @param {number=} i The index to read.
137			* @return {number}
138			* @private
139			*/
140			readBits_(bytes, i=0) {
141			/** @type {string} */
142			let binary = '';
143			for (let j = 0; j < this.offset_; j++) {
144			/** @type {string} */
145			let bits = bytes[i + j].toString(2);
146			binary = new Array(9 - bits.length).join('0') + bits + binary;
147			}
148			return this.overflow_(this.sign_(parseInt(binary, 2)));
149			}
150
151			/**
152			* Build the type.
153			* @throws {Error} if the number of bits is smaller than 1 or greater than 64.
154			* @private
155			*/
156			build_() {
157			this.setRealBits_();
158			this.setLastByteMask_();
159			this.offset_ = this.bits_ < 8 ? 1 : Math.ceil(this.realBits_ / 8);
160			if ((this.realBits_ != this.bits_) \|\| this.bits_ < 8 \|\| this.bits_ > 32) {
161			this.write = this.writeEsoteric_;
162			this.read = this.readBits_;
163			}
164			}
165
166			/**
167			* Sign a number.
168			* @param {number} num The number.
169			* @return {number}
170			* @private
171			*/
172			sign_(num) {
173			if (num > this.max_) {
174			num -= (this.max_ * 2) + 2;
175			}
176			return num;
177			}
178
179			/**
180			* Trows error in case of underflow or overflow.
181			* @param {number} num The number.
182			* @return {number}
183			* @throws {Error} on overflow or underflow.
184			* @private
185			*/
186			overflow_(num) {
187			if (num > this.max_) {
188			throw new Error('Overflow.');
189			} else if (num < this.min_) {
190			throw new Error('Underflow.');
191			}
192			return num;
193			}
194
195			/**
196			* Set the practical bit number for data with bit count different
197			* from the standard types (8, 16, 32, 40, 48, 64).
198			* @private
199			*/
200			setRealBits_() {
201			this.realBits_ = ((this.bits_ - 1) \| 7) + 1;
202			}
203
204			/**
205			* Set the mask that should be used when writing the last byte.
206			* @private
207			*/
208			setLastByteMask_() {
209			/** @type {number} */
210			let r = 8 - (this.realBits_ - this.bits_);
211			this.lastByteMask_ = Math.pow(2, r > 0 ? r : 8) - 1;
212			}
213
214			/**
215			* Write the first byte of a integer number.
216			* @param {!Array<number>} bytes An array of bytes.
217			* @param {number} number The number.
218			* @param {number} j The index being written in the byte buffer.
219			* @return {number} The next index to write on the byte buffer.
220			* @private
221			*/
222			writeFirstByte_(bytes, number, j) {
223			if (this.bits_ < 8) {
224			bytes[j] = number < 0 ? number + Math.pow(2, this.bits_) : number;
225			} else {
226			bytes[j] = number & 255;
227			}
228			return j + 1;
229			}
230			}
231

rochars / byte-data

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integer.js ➔ setLastByteMask_ A

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