configure.in

This and the macro-definition file aclocal.m4 are the sources for the configure script. Autoconf should be run in this directory if either of these files is editted.

Once the script has determined the host architecture, it checks the known-architecture directory for any preferred compilers. By default autoconf macros will choose GNU CC if it is available, however for some architectures this may not be desirable.

It then proceeds to determine the available compilers and auxiliary programs if they haven't alrady been specified in an environment variable or in the known-architecture file for this architecture.

Once the set of programs to be used has been detected or chosen, the known-architecture files are again checked for specific features which would otherwise require the writing of complicated macros to detect. (Remember that the goal is that people don't need to write autoconf macros or run autoconf themselves.)

Once that is done it looks at each subdirectory of the extras directory for packages which have their own configuration process. If a subdirectory has an exectubale file called setup.sh this is called.

The rest of the script is concerned with detecting various header files, sizes of various types, and of setting defaults for things which haven't been set by the known-architecture file.