Package Exports

byte-data

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Readme

byte-data

Bytes to and from numbers and strings.
Copyright (c) 2017 Rafael da Silva Rocha.
https://github.com/rochars/byte-data

Install

npm install byte-data

For Node.js and the browser.

Arguments can be Array, Uint8Array and Buffer objects.

byte-data functions always return regular arrays.

Bytes can be represented as numbers or as hex and binary strings both in the input and the output. Decimal is assumed by default in both cases.

Support:

booleans
crumbs (2-bit, signed/unsigned)
nibbles (4-bit, signed/unsigned)
8-bit int (signed/unsigned)
16-bit int (signed/unsigned)
24-bit int (signed/unsigned)
32-bit int (signed/unsigned)
32-bit float
40-bit ints (signed/unsigned)
48-bit int (signed/unsigned)
64-bit double
Strings

Example

intTo4Bytes([-2147483648, 2147483647]);
// returns [0,0,0,128,255,255,255,127]

intFrom4Bytes([0,0,0,128,255,255,255,127]);
// returns [-2147483648, 2147483647]

Use

let byteData = require('byte-data');

/**
 * numbers to bytes, all:
 * @param {!Array<number>} numbers The numbers.
 * @param {number} base Base 2, 10 or 16. If ommited defaults to 10.
 * @param {boolean} bigEndian If the bytes are big endian. Defaults to false.
 * @return {!Array<number>} the bytes.
 */
bytes = byteData.doubleTo8Bytes(numbers);
bytes = byteData.intTo6Bytes(numbers);
bytes = byteData.intTo5Bytes(numbers);
bytes = byteData.floatTo4Bytes(numbers);
bytes = byteData.intTo4Bytes(numbers);
bytes = byteData.intTo3Bytes(numbers);
bytes = byteData.intTo2Bytes(numbers);
bytes = byteData.intTo1Byte(numbers);

/**
 * numbers from bytes, all:
 * @param {!Array<number>|Uint8Array} bytes An array of bytes.
 * @param {number} base Base 2, 10 or 16. If ommited defaults to 10.
 * @param {boolean} bigEndian If the bytes are big endian. Defaults to false.
 * @return {!Array<number>} The numbers.
 */
numbers = byteData.doubleFrom8Bytes(bytes);
numbers = byteData.doubleFrom8Bytes(bytes);
numbers = byteData.intFrom6Bytes(bytes);
numbers = byteData.uIntFrom6Bytes(bytes);
numbers = byteData.intFrom5Bytes(bytes);
numbers = byteData.uIntFrom5Bytes(bytes);
numbers = byteData.intFrom4Bytes(bytes);
numbers = byteData.uIntFrom4Bytes(bytes);
numbers = byteData.intFrom3Bytes(bytes);
numbers = byteData.uIntFrom3Bytes(bytes);
numbers = byteData.intFrom2Bytes(bytes);
numbers = byteData.uIntFrom2Bytes(bytes);
numbers = byteData.intFrom1Byte(bytes);
numbers = byteData.uIntFrom1Byte(bytes);

// Booleans, crumbs and nibbles
numbers = byteData.intFromNibble(bytes);
numbers = byteData.uIntFromNibble(bytes);
numbers = byteData.intFromCrumb(bytes);
numbers = byteData.uIntFromCrumb(bytes);
numbers = byteData.fromBoolean(bytes);
bytes = byteData.intToNibble(numbers);
bytes = byteData.toCrumb(numbers);
bytes = byteData.toBoolean(numbers);

// strings
bytes = byteData.stringToBytes(string);
string = byteData.stringFromBytes(bytes);

// look for some string and return the start offset
// of its first occurrence in the buffer 
index = byteData.findString(bytes, "chunk");

Bytes are returned in base 10 by default.

byteData.intTo4Bytes([-2147483648]);
// returns [0, 0, 0, 128]

To get hex values:

byteData.intTo4Bytes([-2147483648], 16)
//["00", "00","00","80",]

To get binaries:

byteData.intTo4Bytes([-2147483648], 2)
//["00000000", "00000000","00000000","10000000",]

Binary nibbles:

byteData.intToNibbles([6], 2)
//["0110"]

Little Endian vs Big Endian

Bytes are little endian by default.

To get big endian bytes:

byteData.intTo5Bytes([1], 10, true);
//[0, 0, 0, 0, 1]

To read big endian bytes:

byteData.intFrom3Bytes(["80","00","00","00","00","01","7f", "ff", "ff"], 16, true);
//[-8388608, 1, 8388607]

Pack your nibbles

Packing nibbles:

byteData.packNibbles([15, 15, 1, 4, 1, 15]);
//[255, 20, 31]);

This will pack 2 nibbles into one byte.

Unpacking nibbles:

byteData.unpackNibbles([255, 20, 31]);
//[15, 15, 1, 4, 1, 15]

Browser

<script src="byte-data-min.js"></script>
<script>
    let byteString = stringToBytes("ab"); // [97, 98]
    let myString = stringFromBytes([97, 98]); //"ab";
    ...
</script>

Python struct.pack VS Node.js byte-data

//struct.pack('<c', "a")
byteData.stringToBytes("a", 16);

//struct.pack('<b', -1)
byteData.intTo1Byte([-1], 16);

//struct.pack('<B', 1)
byteData.intTo1Byte([1], 16);

//struct.pack('<h', -1)
byteData.intTo2Bytes([-1], 16);

//struct.pack('<H', 1)
byteData.intTo2Bytes([1], 16);

//struct.pack('<i', -2147483648)
byteData.intTo4Bytes([-2147483648], 16);

//struct.pack('<I', 4294967295)
byteData.intTo4Bytes([4294967295], 16);

LICENSE

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.