varints

varint.js

function lshift(num, bits) {
    return num * Math.pow(2, bits);
}

function rshift(num, bits) {
    return num / Math.pow(2, bits);
}

function encode(num) {
    if (num === 0) return new Buffer([0x00]);
    var bytes = [];
    while (num >= 0x80) {
        bytes.push(num | 0x80);
        num = rshift(num, 7);
    }
    bytes.push(num);
    return new Buffer(bytes);
}

function decode(varint) {
    var nextByte,
        result = 0,
        bytesRead = 0;
    do {
        nextByte = varint[bytesRead];
        result += lshift((nextByte & 0x7F), (7 * bytesRead));
        bytesRead++;
    } while (nextByte >= 0x80);
    return { num: result, bytes: bytesRead };
}