use divide when number is too large for bitwise operations

encode.js

@@ -3,17 +3,22 @@ module.exports = encode
 var MSB = 0x80
   , REST = 0x7F
   , MSBALL = ~REST
+  , INT = Math.pow(2, 31)
 
 function encode(num, out, offset) {
   out = out || []
   offset = offset || 0
   var oldOffset = offset
 
-  while(num & MSBALL) {
+  while(num >= INT) {
+    out[offset++] = (num & 0xFF) | MSB
+    num /= 128
+  }
+  while(num >= 0x80) {
     out[offset++] = (num & 0xFF) | MSB
     num >>>= 7
   }
-  out[offset] = num
+  out[offset] = num | 0
   
   encode.bytesWritten = offset - oldOffset + 1