Merge pull request #4 from mafintosh/patch-1

Add encode.bytesWritten

README.md

@@ -27,6 +27,10 @@ decodes `data`, which can be either a buffer or array of integers, from position
 
 if you also require the length (number of bytes) that were required to decode the integer you can access it via `varint.decode.bytesRead`. this is an integer property that will tell you the number of bytes that the last .decode() call had to use to decode.
 
+### varint.encode.bytesWritten
+
+similar to `bytesRead` when encoding a number it can be useful to know how many bytes where written (especially if you pass an output array). you can access this via `varint.encode.bytesWritten` which holds the number of bytes written in the last encode.
+
 ## usage notes
 
 if you are using this to decode buffers from a streaming source it's up to you to make sure that you send 'complete' buffers into `varint.decode`. the maximum number of bytes that varint will need to decode is 8, so all you have to do is make sure you are sending buffers that are at least 8 bytes long from the point at which you know a varint range begins.

encode.js

@@ -7,11 +7,15 @@ var MSB = 0x80
 function encode(num, out, offset) {
   out = out || []
   offset = offset || 0
+  var oldOffset = offset
 
   while(num & MSBALL) {
     out[offset++] = (num & 0xFF) | MSB 
     num >>>= 7
   }
   out[offset] = num
+  
+  encode.bytesWritten = offset - oldOffset + 1
+  
   return out
 }

test.js

@@ -60,12 +60,14 @@ test('test decode multiple bytes with zero', function(assert) {
 test('encode single byte', function(assert) {
   var expected = randint(parseInt('1111111', '2'))
   assert.deepEqual(encode(expected), [expected])
+  assert.equal(encode.bytesWritten, 1)
   assert.end()
 })
 
 test('encode multiple byte with zero first byte', function(assert) {
   var expected = 0x0F00
   assert.deepEqual(encode(expected), [0x80, 0x1E])
+  assert.equal(encode.bytesWritten, 2)
   assert.end()
 })