bits – Bits <3 Buffers

A tool for twiddling bits in buffers

Installation

npm install --save @fry/bits

Usage

Create a 0-filled bit-buffer with a length of any given bit-length

const{ Bits }=require('@fry/bits');constbits=newBits(15*8);// 15 bytes capacity

Or reference an already exisiting Buffer

constbuffer=Buffer.from([0xff,0x00,0xff,0x00]);constbits=newBits(buffer);

There are also convenience functions to create prefilled buffers (note that these use byte-length arguments)

constbits=Bits.alloc(6,0xaa);// 6 * 8 bits capacity, with 0b10101010... repeated for all bits

constbits=Bits.from('Yml0YnVm','base64');// 48 bits capacity prefilled with data

After instantiating the bit-buffer you can begin manipulating the bits

constbits=newBits(2*8);// Write some bits, jump to the beginning of the buffer and read all bitsconstvalue=bits.write(7,3).write(0x55,7).write(0b10,2).seek(0).read(12);// value = 0b111101010110// Turn on bit 4 and 5bits.insert(0b11,2,4);// Read the same 2 bits, not moving the offsetbits.peek(2,4);// 0b11// Get bit 4bits.getBit(4);// 0b1// Set bit 5 to 1bits.setBit(5);// Test if bit 5 is 1bits.testBit(5);// true// Clear bit 5 and flip bit 6bits.clearBit(5).flipBit(6);// Stringify the buffer (e.g. ascii, utf8, ucs2, base64, binary, hex)bits.toString('hex');// 'fb60'