vlq-buffer

vlq-buffer

A simple set of functions for converting between integer and VLQ buffer values

Installation

$ npm install --save vlq-buffer

Reference vlq-buffer

var vlqBuffer = require('vlq-buffer');

Usage

int2VLQBuffer

This method converts an integer to a Buffer containing the VLQ representation of that integer.

var myInt = 2097151;
var bufferValue = vlqBuffer.int2VLQBuffer(myInt);

// bufferValue == <Buffer ff ff 7f>

vlqBuffer2Int

This method converts a Buffer containing a VLQ value to an integer.

var myVLQValue = new Buffer([0x81, 0x80, 0x00]);
var intValue = vlqBuffer.vlqBuffer2Int(myVLQValue);

// intValue == 16384

isVLQLastByte

This method returns true if the given integer's binary value starts with zero, indicating tne end of the VLQ value. This is useful for identifying the final byte in a VLQ value when reading binary data.

var vlqStartIndex = readIndex; // start reading a vlq value and the current read index
var currentByte = bufferData.readUInt8(readIndex);
while (!vlqBuffer.isVLQLastByte(currentByte)) {
        if (++readIndex >= bufferData.length) throw 'EOF error'; // EOF, no vql end found
    currentByte = bufferData.readUInt8(readIndex);
}
var vlqValueBytes = bufferData.slice(vlqStartIndex, ++readIndex);
var intValue = vlq.vlqBuffer2Int(vlqValueBytes);