Bug in Writer.prototype.writeVarInt

[harlos0517]

The original code (midi-writer.js:309) parses integers in the wrong way : only the first bit of MSB is 1.

> 18432456468
10000100
01010101
00100011
01101110
00010100

The correct result is that the first bit of all bytes except LSB is 1.

> 18432456468
10000100 
11010101 
10100011 
11101110 
00010100 

The fixed test code I'm using :

const leftpad = require('left-pad')

var v = 18432456468
if (v < 0) throw "Cannot write negative variable-length integer"

if (v <= 0x7F) {
  console.log(leftpad(v.toString(2),8,'0'))
} else {
  var i = v
  var bytes = []
  bytes.push(i & 0x7F)
  i >>= 7
  while (i) {
    var b = i & 0x7F | 0x80
    bytes.push(b)
    i >>= 7
  }
  bytes.reverse().forEach((e,i)=>{
    console.log(leftpad(e.toString(2),8,'0'))
  })
}

midi-writer.js:309 should be

Writer.prototype.writeVarInt = function(v) {
  if (v < 0) throw "Cannot write negative variable-length integer"

  if (v <= 0x7F) {
    this.writeUInt8(v)
  } else {
    var i = v
    var bytes = []
    bytes.push(i & 0x7F)
    i >>= 7
    while (i) {
      var b = i & 0x7F | 0x80
      bytes.push(b)
      i >>= 7
    }
    this.writeBytes(bytes.reverse())
  }
}

I was trying to use this package for handling some midi data and found this bug.
Hope you can fix it, thanks.

---

Deemo Harlos