Passed
Push — master ( 0d02ce...fc63cf )
by Rafael S.
01:35
created

helpers.js ➔ bytesToBase   A

Complexity

Conditions 3
Paths 3

Size

Total Lines 11

Duplication

Lines 0
Ratio 0 %

Importance

Changes 1
Bugs 0 Features 0
Metric Value
cc 3
c 1
b 0
f 0
nc 3
nop 3
dl 0
loc 11
rs 9.4285
1
/*
2
 * helpers: functions to work with bytes and byte arrays.
3
 * Copyright (c) 2017 Rafael da Silva Rocha.
4
 * https://github.com/rochars/byte-data
5
 */
6
7
const endianness = require("endianness");
8
const bitDepths = require("../src/bit-depth.js");
9
10
/**
11
 * Padding for binary strings.
12
 * @param {!Array<string>} bytes The bytes as binary strings.
13
 * @param {number} base The base.
14
 * @param {number} index The byte to pad.
15
 */
16
function padding(bytes, base, index) {
17
    bytes[index] = bytePadding(bytes[index], base);
18
}
19
20
/**
21
 * Padding with 0s for byte strings.
22
 * @param {string} theByte The byte as a binary or hex string.
23
 * @param {number} base The base.
24
 * @returns {string} The padded byte.
25
 */
26
function bytePadding(theByte, base) {
27
    let offset = theByte.length + 1;
28
    if (base == 2) {
29
        offset = 8;
30
    } else if (base == 16) {
31
        offset = 2;
32
    }
33
    return lPadZeros(theByte, offset);
34
}
35
36
/**
37
 * Fix the size of nibbles.
38
 * @param {!Array<string>} nibbles The nibble as a binary or hex string.
39
 * @param {number} base The base.
40
 * @param {number} index The nibble offset.
41
 */
42
function paddingNibble(nibbles, base, index) {
43
    if (base == 2 && nibbles[index].length < 4) {
44
        nibbles[index] = 
45
            new Array((5 - nibbles[index].length)).join("0")  + nibbles[index];
46
    }
47
}   
48
49
/**
50
 * Fix the size of crumbs.
51
 * @param {!Array<string>} crumbs The nibble as a binary or hex string.
52
 * @param {number} base The base.
53
 * @param {number} index The nibble offset.
54
 */
55
function paddingCrumb(crumbs, base, index) {
56
    if ((base == 2 || base == 16) && crumbs[index].length < 2) {
57
        crumbs[index] = '0' + crumbs[index];
58
    }
59
}   
60
61
/**
62
 * Pad a string with zeros to the left.
63
 * TODO: This should support both arrays and strings.
64
 * @param {string} value The string (representing a binary or hex value).
65
 * @param {number} numZeros the max number of zeros.
66
 *      For 1 binary byte string it should be 8.
67
 */
68
function lPadZeros(value, numZeros) {
69
    while (value.length < numZeros) {
70
        value = '0' + value;
71
    }
72
    return value;
73
}
74
75
/**
76
 * Swap the endianness to big endian.
77
 * @param {!Array<number>} bytes The values.
78
 * @param {boolean} isBigEndian True if the bytes should be big endian.
79
 * @param {number} bitDepth The bitDepth of the data.
80
 */
81
function makeBigEndian(bytes, isBigEndian, bitDepth) {
82
    if (isBigEndian) {
83
        endianness(bytes, bitDepths.BitDepthOffsets[bitDepth]);
84
    }
85
}
86
87
/**
88
 * Turn bytes to base 2, 10 or 16.
89
 * @param {!Array<string>|!Array<number>} bytes The bytes.
90
 * @param {number} base The base.
91
 * @param {Function} padFunction The function to use for padding.
92
 */
93
function bytesToBase(bytes, base, padFunction=padding) {
94
    if (base != 10) {
95
        let i = 0;
96
        let len = bytes.length;
97
        while (i < len) {
98
            bytes[i] = bytes[i].toString(base);
99
            padFunction(bytes, base, i);
100
            i++;
101
        }
102
    }
103
}
104
105
/**
106
 * Turn the output to the correct base.
107
 * @param {!Array<number>} bytes The bytes.
108
 * @param {number} bitDepth The bit depth of the data.
109
 * @param {number} base The desired base for the output data.
110
 */
111
function outputToBase(bytes, bitDepth, base) {
112
    if (bitDepth == 4) {
113
        bytesToBase(bytes, base, paddingNibble);
114
    } else if (bitDepth == 2) {
115
        bytesToBase(bytes, base, paddingCrumb);
116
    } else if(bitDepth == 1) {
117
        bytesToBase(bytes, base, function(){});
118
    }else {
119
        bytesToBase(bytes, base);
120
    }
121
}
122
123
/**
124
 * Turn a unsigned number to a signed number.
125
 * @param {number} num The number.
126
 * @param {number} maxValue The max range for the number bit depth.
127
 */
128
function signed(num, maxValue) {
129
    if (num > parseInt(maxValue / 2, 10) - 1) {
130
        num -= maxValue;
131
    }
132
    return num;
133
}
134
135
/**
136
 * Fix the endianness of float16 bytes (r/w is always big-endian).
137
 * @param {!Array<number>|Uint8Array} bytes The bytes.
138
 * @param {Object} options The type.
139
 */
140
function fixFloat16Endianness(bytes, options) {
141
    if (options.float && options.bits == 16) {
142
        endianness(bytes, 2);
143
    }
144
}
145
146
/**
147
 * Get the full type spec for the reading/writing.
148
 * @param {Object} atype One of the available types.
149
 * @param {number} base The base of the input.
150
 * @param {boolean} single True if its a single value, false for array.
151
 * @return {Object}
152
 */
153
function getType(atype, base, single) {
154
    let theType = Object.assign({}, atype);
155
    theType.base = base;
156
    theType.single = single;
157
    if (theType.bits == 64) {
158
        theType.float = true;
159
    }
160
    if (theType.float) {
161
        theType.signed = true;
162
    }
163
    return theType;
164
}
165
166
/**
167
 * Make a single value an array in case it is not.
168
 * If the value is a string it stays a string.
169
 * @param {!Array<number>|number|string} values The value or values.
170
 * @return {!Array<number>|string}
171
 */
172
function turnToArray(values) {
173
    if (!Array.isArray(values) && typeof values != "string") {
174
        values = [values];
175
    }
176
    return values;
177
}
178
179
180
module.exports.makeBigEndian = makeBigEndian;
181
module.exports.bytesToBase = bytesToBase;
182
module.exports.outputToBase = outputToBase;
183
module.exports.signed = signed;
184
module.exports.padding = padding;
185
module.exports.paddingNibble = paddingNibble;
186
module.exports.paddingCrumb = paddingCrumb;
187
module.exports.bytePadding = bytePadding;
188
module.exports.lPadZeros = lPadZeros;
189
module.exports.fixFloat16Endianness = fixFloat16Endianness;
190
module.exports.getType = getType;
191
module.exports.turnToArray = turnToArray;
192