mirror of https://github.com/dirtbags/tanks.git
74 lines
3.1 KiB
Plaintext
74 lines
3.1 KiB
Plaintext
History
|
|
=======
|
|
|
|
This is a port of the "Tanks" program written by Paul Ferrell
|
|
<pflarr@clanspum.net> in 2009-2010. Paul created the entire game based
|
|
off a brief description I provided him of Crobots and a vague desire to
|
|
"make something fun for high school kids to learn some programming." We
|
|
ran Paul's Tanks as part of a 100-attendee computer security contest in
|
|
February of 2010 and by all accounts it was a huge success. It even
|
|
made the nightly news.
|
|
|
|
Paul's version was written in Python and provided a custom language
|
|
called "Bullet", which looked like this:
|
|
|
|
>addsensor(50, 0, 5, 1); # 0
|
|
>addsensor(100, 90, 150, 1); # 1
|
|
>addsensor(100, 270, 150, 1); # 2
|
|
>addsensor(100, 0, 359, 0); # 3
|
|
|
|
# Default movement if nothing is detected
|
|
: move(70, 70) . turretccw();
|
|
random(2, 3): move(40, 70) . turretccw();
|
|
random(1, 3): move(70, 40) . turretccw();
|
|
|
|
# We found something!!
|
|
sense(3): move(0, 0);
|
|
sense(1): turretcw();
|
|
sense(2): turretccw();
|
|
sense(0): fire();
|
|
|
|
Nick Moffitt played with this original version and convinced me (Neale)
|
|
that something like Forth would be a better language. I added some code
|
|
to accept a scaled-down version of PostScript. The IRC channel we
|
|
frequent collectively agreed to give this new language the derisive name
|
|
"Forf", which should ideally be followed by punching someone after it is
|
|
spoken aloud.
|
|
|
|
I decided to take Tanks to Def Con in July 2010, and just for bragging
|
|
rights, to have it run on an Asus WL-500gU. This is a $50 device with a
|
|
240 MHz MIPS CPU, 16MB RAM, and a 4MB flash disk, along with an
|
|
802.11b/g radio, 4-port 10/100 switch, and an additional 10/100 "uplink"
|
|
port; it's sold as a home wireless router. I had originally intended to
|
|
run it off a lantern battery just for fun, but eventually thought better
|
|
of it: doing so would be wasteful for no good reason.
|
|
|
|
Aaron McPhall <amcphall@mcphall.org>, my summer intern at the time, got
|
|
OpenWRT and Python onto the box and benchmarked it at about 60 seconds
|
|
for a 16-tank game, after he had profiled the code and optimized a lot
|
|
of the math. That wasn't bad, it meant we could run a reasonably-sized
|
|
game at one turn per minute, which we knew from past experience was
|
|
about the right rate. But it required a USB thumb drive to hold Python,
|
|
and when we used the Python Forf implementation, the run-time shot up to
|
|
several minutes. I began this C port while Adam Glasgall, another fool
|
|
on the previously-mentioned IRC channel, started work on a C version of
|
|
a Forf interpreter.
|
|
|
|
This C version with Forf runs about 6 times faster than the Python
|
|
version with Bullet, on the WL-500gU. A 1GHz Intel Atom runs a 16-tank
|
|
game in about 0.2 seconds.
|
|
|
|
|
|
What's so great about Forf?
|
|
---------------------------
|
|
|
|
Nothing's great about Forf. It's a crummy language that only does
|
|
integer math. For this application it's a good choice, for the
|
|
following reasons:
|
|
|
|
* No library dependencies, not even malloc
|
|
* Runs in fixed size memory
|
|
* Not Turing-complete, I think (impossible to make endless loops)
|
|
* Lends itself to genetic algorithms
|
|
|