This is a port to Ada of cempire (see

     https://github.com/jimwise/cempire

).  This is very much a work in progress -- it works, but is missing
some functionality of the C version, and is still not completely stable.

This code is Copyright (C) 2006-2012 Jim Wise

As a derivative work (a straight port) of a program under a GPL-like
license, this software is offered under the same license as that program --
this corresponds with the author's clear intent, although it may not be a
legal necessity.


--- Below is the README from the C version ----


/*
 *    Copyright (C) 1987, 1988 Chuck Simmons
 * 
 * See the file COPYING, distributed with empire, for restriction
 * and warranty information.
 *
 * $Id: READ.ME,v 1.1 2006/02/21 17:33:41 jwise Exp $
 */

C Empire Sources

History

	Apparently, this game was originally written outside of Digital,
	probably at a university.  The game was ported to DEC's VAX/VMS
	from the TOPS-10/20 FORTRAN sources available around fall 1979.
	Ed James got hold of the sources at Berkeley and converted
	portions of the code to C, mostly to use curses for the screen
	handling.  He published his modified sources on the net in
	December 1986.  Because this game ran on VMS machines for so
        long, a previous version is known as VMS Empire.

	In early 1987 Chuck Simmons reverse engineered the program and wrote
	a version completely written in C.  In doing this, I used lots of
	structures and defined constants, and I attempted to make the code
	flexible and easy to modify.  The algorithms used in this C version
	are completely new, the names of the commands have been changed to
	be more mnemonic, and new commands have been implemented.  Only the
	format of the display is the same.  I suspect that many of my
	changes are slower and less intelligently implemented than the
	originals.  Also, I have not implemented some of the original
	functionality.  However, my hope is that the commented C sources I
	have written will prove far easier to modify and enhance than the
	original FORTRAN sources.  If you make changes for the better, by
	all means send Ed James and I a copy.

	Sometime thereafter, Eric S. Raymond took over work on C-Empire, adding 
	color support and some modernizations.  In 1998, the torch passwd to
	Jim Wise, who has brought the code up to modern C standards, ported
	it to not assume the presence of the GNU ncurses library, and
	otherwise maintained the code against bit-rot.

	The basic game has been heavily modified since 1979 -- the types of
	objects built have changed, as have the parameters on others, and
	lots of new kinds of movement functions have been added.  Read the
	man page for a complete description.

	The file 'bugs' contains lots of ideas for enhancements, and
	describes the bugs I haven't been able to find.

Organization

        I have attempted to organize the sources into relatively few
        coherent pieces.  The pieces are:

        empire.h   -- definitions of data structures
        extern.h   -- definitions of global variables
        data.c     -- constant data
	main.c     -- option parsing
        empire.c   -- main program loop and outermost command handler
        usermove.c -- move the user's pieces
        compmove.c -- move the computer's pieces
        edit.c     -- handle the user's edit mode commands
        game.c     -- saving, restoring, and initializing the game board
        display.c  -- update the screen
	term.c     -- deal with information area of screen
        math.c     -- mathematical routines
        object.c   -- routines for manipulating objects
	attack.c   -- handle attacks between pieces
	map.c      -- find paths for moving pieces
	util.c     -- miscellaneous routines, especially I/O.

Debugging notes

	From command mode, there are two special commands that
	can be used to turn debugging mode on or off.  "++" turns
	debugging mode on.  "+-" turns debugging mode off.

	When debugging mode is turned on, the following commands are
	available:

	"#" -- display a sector of the computer's map.

	"%" -- enter "movie" mode.  The computer continuously makes
	       moves, and the computer's map is shown on the screen.
	       This is useful for debugging the algorithm used by the
	       computer when it makes a move.  Don't confuse this
	       with saving a movie and replaying it.

	"@" -- enable/disable "trace pathmap" mode.  If this command
	       is followed by a "+", trace pathmap mode is enabled.
	       If this command is followed by a "-", trace pathmap
	       mode is disabled.  In this mode, every time a "pathmap"
	       is created, it is displayed.  This is useful for
	       debugging the subroutines that search for an optimal
	       path along which to move a piece.

	"$" -- enable/disable "print_debug".  This command is also
	       followed by either a "+" or "-".  In this mode,
	       various messages will be printed out at times which
	       may indicate that something is being done non-optimally.

	"&" -- enable/disable "print_vmap".  This command is followed
	       by a char that specifies the type of vmap to be
	       displayed.  Values are

		"a" -- army load maps
		"l" -- transport load maps
		"u" -- transport unload maps
		"s" -- ship maps
		"i" -- pruned explore map

	       Any other character disables the printing of vmaps.

	The program will not provide any prompts for the debugging
	commands.  If you make a mistake, the computer just beeps.

	You can also replay a saved movie with the normal "W" command
	when debugging mode is turned on.

	Also, the -DDEBUG flag can be turned on to cause consistency
	checking to be performed frequently on the internal database.
	This consistency checking is fairly exhaustive and checks for
	all sorts of screwed up pointers.  My measurements suggest
	that consistency checking causes the program to run half
	as fast.

Final Notes

	Unfortunately, I have a rather powerful mainframe at my
	disposal which is somewhere between 10 and 40 times as
	fast as a 68020 based computer.  This means I can afford
	to use extremely inefficient algorithms.  I suspect that
	running this program on a smaller machine, such as a Sun
	workstation or Vax will not be overly rewarding.  In particular,
	the computer will take a very long time to move its pieces,
	and it may not be desirable to save the game after every move.
	(You mean your system doesn't write out 1/2 megabyte files in a
	few milliseconds?)  This second problem is easily fixed, but
	I don't yet have any good ideas for fixing the first problem.

	The size of a saved file can be easily tuned by reducing the
	LIST_SIZE constant in empire.h.  The only current simple tweak
	for making the computer move faster is to reduce the size
	of a map.

Chuck Simmons
amdahl!chuck

Ed James
edjames@ic.berkeley.edu
ucbvax!edjames

	My changes enable color on machines with terminfo color support, for
	a dramatic improvement in appearance and readability of the display.
	Color support, if present, will be auto-detected at compilation time.

	They also implement and document a `save-interval' option, addressing
	one of the misfeatures noted in the bugs file.

	I've also tweaked the sources so they compile clean under GCC -- they
	assumed the older K&R model of forward reference, causing many warning
	references.

	Finally, I've sped up expand_perimeter by cutting down on the
	number of array references it has to compute. This eliminates several
	multiplies from the inner loop, and is a technique that should be
	applied much more widely in the code.

Eric S. Raymond
esr@snark.thyrsus.com
(home page: //www.ccil.org/~esr/home.html)

Jim Wise
jwise@draga.com
http://www.draga.com/~jwise/cempire/