FIPS Standard

• Equivalence of variables should not be used to permit multiple memory usage for conflicting
purposes.
• Robust command parsing and range checking mechanisms should be implemented to guard
against malformed requests, out-of-range parameters, and I/O buffer overflows.
IN-LINE DOCUMENTATION
• Each software module, procedure, and major programming construct should be documented
specifying the functions performed along with a (formal or informal) specification of
preconditions and postconditions.
• Each loop should be preceded by a convincing argument (as a comment) that termination is
guaranteed.
• Variable names should be used in only one context within the same procedure.
• Each variable should have an associated comment identifying the purpose of the variable and
noting the range of allowable values, including if the range is unrestricted.
• If concurrency is employed, the documentation should specify how limits are enforced on the
maximum allowable degree of concurrency and how accesses to shared data are synchronized in
order to avoid (possibly undetected) run-time errors.
ASSEMBLY LANGUAGE
The following additional programming practices should be used when the implementation is in assembly
language.
• All code should be position independent except where appropriate security concerns, efficiency, or
hardware constraints require position dependency.
• All register references should use symbolic register names.
• Self-modifying code should not be used.
• All procedures should be responsible for saving and restoring the contents of any register that is
used within the procedure.
• Control transfer instructions should not use numeric literals.
• Each unit should contain comments describing register use in the unit.
46