Is there a difference in intended meaning between .s (lower-case) and .S (upper-case) assembly files?

Question

I have noticed that some libraries ship with assembly files using a .s extension, and others ship assembly files with a .S extension. GCC seems to handle these differently.

Is there any intended meaning behind these two different extensions?

Answer 1

The difference is that .S (uppercase) files are first run through the C preprocessor and afterwards through the assembler, while .s (lowercase) files do not contain any preprocessor directives and are fed directly to the assembler.