title: How to write an efficient Go implementation of built-in function copy?
body: <p>I have two byte buffers <code>var a,b []byte</code>, I am looking for a replacement for Go's built-in copy function to copy from one byte buffer to the other, preferably pure Go implementation and efficiency is important.</p>
  
  <p>The reason is that <code>copy</code> reliably crashes my program due to <code>unexpected fault address</code>, therefore I would like to experiment with a non-native <code>copy()</code> replacement to find out if the crash was caused by my program logics or not.</p>