ftp://ftp.uni-heidelberg.de/pub/X11/contrib/applications/xscreensaver-1.25.tar.Z

[xscreensaver] / utils / README

This directory contains various utilities that are used both by the 
screensaver driver and by the demo programs; for example, a portable
implementation of usleep(), and code for manipulating color maps.

If you have compilation problems, check the parameters in ../config.h.