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/