BitPacker

A TypeScript library for bit-level packing and unpacking of binary data. Supports reading and writing integers (signed/unsigned), floating-point numbers, raw bytes, and individual bits.

Features

• Fine-grained bit-level writing and reading
• Support for:
  • Unsigned integers (Uint8, Uint16, Uint32)
  • Signed integers (Int8, Int16, Int32)
  • Floating-point numbers (Float32, Float64)
  • Arbitrary byte arrays
• Optional peek functionality (non-destructive read)

Consuming API

Note that the API is deliberately written that the Unpacker code is mutable/consuming. This is done for memory use reasons.

Installation

deno add jsr:@sck/bitpacker
npx jsr add @sck/bitpacker
bunx jsr add @sck/bitpacker

import { Packer, Unpacker } from "@sck/bitpacker";

Use

Packing data

const packer = new Packer();

packer.putBit(1);
packer.putBits([0, 1, 0]);
packer.putUint8(255);
packer.putInt16(-1234);
packer.putFloat32(Math.PI);
packer.putBytes([1, 2, 3]);

const buffer = packer.getBuffer(); // Uint8Array

Unpacking data

const unpacker = new Unpacker(buffer);

const bit = unpacker.readBit(); // 1
const bits = unpacker.readBits(3); // [0, 1, 0]
const u8 = unpacker.readUint8(); // 255
const i16 = unpacker.readInt16(); // -1234
const pi = unpacker.readFloat32(); // ~3.14159
const bytes = unpacker.readBytes(3); // [1, 2, 3]

Peeking at future data without consuming

const bits = unpacker.peek(4); // preview next 4 bits without advancing

API

Class: Packer

Method	Description
putBit(bit)	Add a single bit (0 or 1)
putBits(bits[])	Add an array of bits
putBytes(bytes)	Add an array of bytes
putUint8(num)	Add an unsigned 8-bit integer
putUint16(num)	Add an unsigned 16-bit integer
putUint32(num)	Add an unsigned 32-bit integer
putInt8(num)	Add a signed 8-bit integer
putInt16(num)	Add a signed 16-bit integer
putInt32(num)	Add a signed 32-bit integer
putFloat32(num)	Add a 32-bit float
putFloat64(num)	Add a 64-bit float
getBytes()	Get internal byte array
getBuffer()	Get final Uint8Array buffer

---

Class: Unpacker

Method	Description
readBit()	Read a single bit
readBits(n)	Read n bits
readUint8()	Read an unsigned 8-bit integer
readUint16()	Read an unsigned 16-bit integer
readUint32()	Read an unsigned 32-bit integer
readInt8()	Read a signed 8-bit integer
readInt16()	Read a signed 16-bit integer
readInt32()	Read a signed 32-bit integer
readFloat32()	Read a 32-bit float
readFloat64()	Read a 64-bit float
readBytes(n)	Read n bytes
peek(n)	Peek the next n bits (non-destructive)

Licence

This project is licensed under the MIT licence.