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