Merge pull request ethereumjs#286 from ethereumjs/optim-byte

Optimise BYTE to only use bn.js

Author: holgerd77

lib/opFns.js

@@ -156,11 +156,7 @@ module.exports = {
       return new BN(0)
     }
 
-    pos = pos.toNumber()
-    word = word.toArrayLike(Buffer, 'be', 32)
-    word = utils.setLengthLeft(word, 32)
-
-    return new BN(word[pos])
+    return word.shrn((31 - pos.toNumber()) * 8).andln(0xff)
   },
   // 0x20 range - crypto
   SHA3: function (offset, length, runState) {