buffer-bits

This component is able to hold a set of bits (NOT bytes) and do operations on them. Could be used to analyze some protocol by yourself...

Quick Example

var Bits = require('buffer-bits');
var myBuffer = Buffer.from([20, 30, 40, 50]);
 
// starting from bit offset 3
// and capture 26 bits after
var myBits = Bits.from(myBuffer, 3, 26);    
 
console.log(myBits.toBinaryString());
// 0b10100000111100010100000110

Features

1. Class Methods
   • Bits.from(buffer [, offset = 0 [, length = buffer.length << 3 ]])
     • create Bits from existing Buffer object
   • Bits.from(bits [, offset = 0 [, length = bits.length ]])
     • create Bits from existing Bits object
   • Bits.alloc(length)
     • create Bits with count of bits and filled with 0
2. Constructor
   • new Bits(buffer, offset, length) *
     • there's NO params validating in this constructor, please DON'T use it for creating new instance...
3. Properties (read-only)
   • length
     • count of the total bits
   • byteLength
     • total bytes the Bits object holds
   • isFullByte
     • return true if total bits count is a multiple of 8
   • buffer
     • inner Buffer object hold by Bits. Take care to NOT write to this buffer directly.
   • startOffset *
     • represents the start bit offset inside the byte. This property should be RARELY used, use it when you know what you're doing...
   • isLeftAligned *
     • represents if all the bits are left aligned in the inner buffer, RARELY
   • isRightAligned *
     • represents if all the bits are right aligned in the inner buffer, RARELY
4. Methods
   • readInt()
     • read integer value of current bits (big endian)
   • readIntLE()
     • read integer value of current bits with little endian
   • readUInt()
     • read unsigned integer value of current bits (big endian)
   • readUIntLE()
     • read unsigned integer value of current bits with little endian
   • readString([encoding[, start[, end]]])
     • read string from the bits, same as buf.toString
   • readBit(index)
     • read the bit value (1: true, 0: false) at position 'index'
   • setBit(index, value)
     • set the bit value (1: true, 0: false) at position 'index'
   • toggleBit(index)
     • toggle the bit value at position 'index', 1->0, 0->1
   • toggleAll()
     • toggle all the bits
   • concat(Bits)
     • create Bits by concating another Bits object
   • toBinaryString()
     • return a '0b<binaryData>' format string, like 0b110101010
   • equals(Bits)
     • return true if all bits equals to another Bits object
   • align(Boolean) *
     • align all the bits inside the inner buffer to the left(true) or right(false) side
   • alignLeft() *
     • align all the bits in the inner buffer to the left side
   • alignRight() *
     • align all the bits in the inner buffer to the right side

More Examples

console.log(myBits.length);
// 26
 
console.log(myBits.byteLength);
// 4
 
console.log(myBits.startOffset);
// 6
 
console.log(myBits.buffer);
// <Buffer 02 83 c5 06>
 
console.log(myBits.readInt());
// 42190086
 
console.log(myBits.readBit(20));
// false
 
myBits.setBit(20, true);
console.log(myBits.readBit(20));
// true

More More Examples

Please check the tests in test folder to see more details.

License

MIT