Automake includes some support for assembly code. There are two forms
of assembler files: normal (*.s) and preprocessed by
(*.S or *.sx).
CCAS holds the name of the compiler used to build
assembly code. This compiler must work a bit like a C compiler; in
particular it must accept -c and -o. The values of
AM_CCASFLAGS (or its per-target
definition) is passed to the compilation. For preprocessed files,
AM_CPPFLAGS are also used.
The autoconf macro
AM_PROG_AS will define
CCASFLAGS for you (unless they are already set, it simply sets
CCAS to the C compiler and
CCASFLAGS to the C compiler
flags), but you are free to define these variables by other means.
Only the suffixes .s, .S, and .sx are recognized by automake as being files containing assembly code.