title: How do I create a single makefile for both 32- and 64-bit?
body: <p>I have a <code>makefile</code> that works transparently for Linux (<code>x86_64</code>) and OS X Intel (<code>x86_64</code>). This uses 64-bit specific GCC options.</p>
  
  <p>Is there a way to adjust the makefile so that I could build for 32-bit and 64-bit OS X PPC (<code>ppc</code>, <code>ppc64</code>) without having to maintain separate, arch-specific makefiles — perhaps something like a pre-processor directive that can determine the architecture before building?</p>