Common Lisp&#x27;s foreign function interface (either implementation specific or cross-platform a la CFFI) allows for the explicit definition of how a foreign structure should be laid out in memory.<p>Even if I&#x27;m not using Lisp for the end product, whose SLA may not permit a runtime with garbage collection, I always find it invaluable to define low-level structures with a Lisp whose machine code compiler is available at runtime for experimental interactive development.<p>A free and open source Lisp that you might enjoy experimenting with is SBCL, available from <a href="http:&#x2F;&#x2F;www.sbcl.org" rel="nofollow">http:&#x2F;&#x2F;www.sbcl.org</a>.<p>Load up the REPL, and follow the manual available here <a href="http:&#x2F;&#x2F;sbcl.org&#x2F;manual&#x2F;index.html#Foreign-Function-Interface" rel="nofollow">http:&#x2F;&#x2F;sbcl.org&#x2F;manual&#x2F;index.html#Foreign-Function-Interface</a>.<p>SBCL also allows you to interactively augment the machine code compiler, install new intrinsics, and disassemble any function interactively.<p>Even if you never use it for production code directly, it might become an invaluable tool in your low level development process.