@xobj/buffer

Buffer for Browser and NodeJS. Writing and reading basic types to binary data.

Install

yarn add @xobj/buffer

Usage

// import reader and writer
import { BufferWriter, BufferReader } from '@xobj/buffer';

// create buffer writer
const writer = new BufferWriter();

// write values
writer.writeInt8(123);
writer.writeString('Test string');

// get result buffer for writing to file or sending to server
const buffer: ArrayBuffer = writer.buffer;

// create buffer reader
const reader = new BufferReader(buffer);

// read values
console.log(reader.readInt8());// 123
console.log(reader.readString()); // Test string

You can see more examples in tests.

Types

• Number
  • uint8
  • uint16
  • uint32
  • uintVar
  • int8
  • int16
  • int32
  • intVar
  • float32
  • float64
• BigInt
• String
• ArrayBuffer
• Boolean
  • flags
  • bitset

uintVar / intVar

Variable length integer (1-5 bytes) with max value 2^53-1 (Number.MAX_SAFE_INTEGER). Big bit indicates about next byte. For signed integer first bit used for sign.

Examples:

const writer = new BufferWriter();
writer.writeUintVar(123456);
console.log(writer.buffer);
// ArrayBuffer { [Uint8Contents]: <c0 c4 07>, byteLength: 3 }

Other cases:

uint [01111011] = 123

int [11110111 00000001] = -123

uint [11000000 11000100 00000111] = 123456

int [10000001 10001001 00001111] = -123456

uint [10101100 11100001 10011011 00000011] = 6746284

uint [10111101 10010011 10011100 10101111 00000001] = 367462845

uint [11001011 11111001 11010111 11100100 11000000 11111110 11110000 00000110] = 3874627647831243

BigInt

BigInt consist of count and bytes array.

| count | values | |-----------|-----------| | uintVar | uint8[] |

const writer = new BufferWriter();
writer.writeBigInt(9007199326476237462784254740991n);
console.log(writer.buffer);
// ArrayBuffer { [Uint8Contents]: <1a ff 09 91 63 c8 ce 83 c6 00 a8 d4 af 71>, byteLength: 14 }

String

String consist of chars length and chars codes array.

| length | chars codes | |-----------|-------------| | uintVar | uintVar[] |

const writer = new BufferWriter();
writer.writeString('simple string, простая строка, 単純な文字列');
console.log(writer.buffer);
// ArrayBuffer {
//   [Uint8Contents]: 
//     <25 73 69 6d 70 6c 65 20 73 74 72 69 6e 67 2c 20 bf 08 c0 08 
//      be 08 c1 08 c2 08 b0 08 cf 08 20 c1 08 c2 08 c0 08 be 08 ba 
//      08 b0 08 2c 20 d8 a6 01 94 fa 01 ea 60 87 cb 01 d7 b6 01 97 
//      a4 01>,
//   byteLength: 62
// }

ArrayBuffer

ArrayBuffer consist of buffer size and data.

| size | data | |-----------|-----------| | uintVar | uint8[] |

Boolean

Flags is a boolean array. It is represented as bits writed as single uintVar value. Maximum array length is 53 (maximum uintVar value).

| flags | |-----------| | uintVar |

Examples:

const writer = new BufferWriter();
writer.writeFlags([true, true, true, false, true, false, false, false, true, true]);
console.log(writer.buffer);
// ArrayBuffer { [Uint8Contents]: <97 06>, byteLength: 2 } 

Bitset is a boolean array too. But represented as bits in flow of bytes.

| bitset | |-----------| | uint8[] |

Examples:

const writer = new BufferWriter();
writer.writeBitset([
	true, true, true, false, true, false, true, true,
	false, true, true, false, true, false, true, false,
]);
console.log(writer.buffer);
// ArrayBuffer { [Uint8Contents]: <d7 56>, byteLength: 2 }

Development

Install all dependencies

yarn

Build project

yarn build

Test project

yarn test

Generate coverage report

yarn coverage

Check code quality

yarn lint