title: 64 bit variable read order (low and high) in 32 bit systems
body: <p>In a 32-bit system, when trying to read a 64-bit variable, which bits will be read first? The high ones or the low ones? Or maybe it varies and we cant depend on it?
  For instance:</p>
  
  <p><code>uint64_t counter = 4;
  uint64_t foo = counter;</code></p>
  
  <p>So when the assignment to foo happens, counter will be read in 2 32-bit parts (low &amp; high), which part is read first? low or high or does it vary?</p>