initial code commit

index.js

@@ -0,0 +1,52 @@
+module.exports = varint
+
+varint.encode = encode
+
+var EE = require('events').EventEmitter
+  , MSB = 0x80
+  , REST = 0x7F
+  , MSBALL = ~REST
+
+function varint() {
+  var ee = new EE
+
+  ee.write = write
+  ee.accum = []
+
+  return ee
+}
+
+function encode(num, out, offset) {
+  out = out || []
+  offset = offset || 0
+
+  while(num & MSBALL) {
+    out[offset++] = (num & 0xFF) | MSB 
+    num >>>= 7
+  }
+  out[offset] = num
+  return out
+}
+
+function write(byte) {
+  var msb = byte & MSB
+    , accum = this.accum
+    , len
+    , out
+
+  accum[accum.length] = byte & REST
+  if(msb) {
+    return
+  }
+
+  len = accum.length
+  out = 0
+
+  for(var i = 0; i < len; ++i) {
+    out |= accum[i] << (7 * i)
+  }
+
+  accum.length = 0
+  this.emit('data', out)
+  return
+}

package.json

@@ -0,0 +1,24 @@
+{
+  "name": "varint",
+  "version": "0.0.0",
+  "description": "use msb to create integer values of varying sizes",
+  "main": "index.js",
+  "scripts": {
+    "test": "node test.js"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/chrisdickinson/varint.git"
+  },
+  "keywords": [
+    "varint",
+    "protobuf",
+    "encode",
+    "decode"
+  ],
+  "author": "Chris Dickinson <chris@neversaw.us>",
+  "license": "MIT",
+  "devDependencies": {
+    "tape": "~0.2.2"
+  }
+}

test.js

@@ -0,0 +1,52 @@
+var varint = require('./index')
+  , test = require('tape')
+
+test('fuzz test', function(assert) {
+  var vi = varint()
+    , expect
+    , encoded
+
+  vi.on('data', function(data) {
+    assert.equal(expect, data, 'fuzz test: '+expect.toString(16))
+  })
+
+  for(var i = 0, len = 100; i < len; ++i) {
+    expect = randint(0x7FFFFFFF)
+    encoded = varint.encode(expect)
+ 
+    for(var x = 0; x < encoded.length; ++x) {
+      vi.write(encoded[x])
+    } 
+  }
+
+  assert.end()
+})
+
+test('test single byte works as expected', function(assert) {
+  var num = [0xAC, 0x02]
+  var acc = varint()
+
+  acc.on('data', function(data) {
+    assert.equal(data, 300, 'should equal 300 every time')
+  })
+
+  for(var i = 0, len = 10; i < len; ++i) {
+    acc.write(0xAC)
+    acc.write(0x02)
+  }
+
+  assert.end()
+})
+
+test('test encode works as expected', function(assert) {
+  var out = []
+
+  assert.deepEqual(varint.encode(300), [0xAC, 0x02])
+
+  assert.end()
+})
+
+
+function randint(range) {
+  return ~~(Math.random() * range)  
+}