upport that instruction, which is straightforward
but only worthwhile if it's likely the instruction will be used again.
Instead, for simple one-off cases, it's possible to use the <code>BYTE</code>
and <code>WORD</code> directives
to lay down explicit data into the instruction stream within a <code>TEXT</code>.
Here's how the 386 runtime defines the 64-bit atomic load function.
</p>

<pre>
// uint64 atomicload64(uint64 volatile* addr);
// so actually
// void atomicload64(uint64 *res, uint64 volatile *addr)