Free software

Here is where I store some programs that are free. If you like something that you see here, please feel free to take it and make it yours. But still free. Thanks.

Image processing

• ImageFmtc.h (.c), a very simple and I think user-friendly interface to various flavors of the BMP, PBM, PGM, and PPM image formats. Also converts between RGB and grayscale very easily.
• ImageGifc.h (.c), a simple implementation of a GIF image writer (no reader yet). After public-domain code by Sverre Huseby, 1992.
• ImagePalc.h (.c), a few functions designed to convert between various internal formats: 8-bit grayscale, 8-bit palettized, and 24-bit RGB formats. Includes an error-diffusion dithering algorithm due to Victor Ostromoukhov.
• simple_png.c, a pair of functions demonstrating a simple interface for reading and writing PNG images using the open-source libpng library.
• UnionFind.h (.c), a very simple implementation of the classic union-find algorithm. It is not reentrant.

Text processing

• Crossword utilities, which I have used in creating crosswords for The Tartan. Includes a crossword dictionary.
• haiku-finder (lib.c, .h), a program for locating "found haiku" in arbitrary text files, as described here. Uses the Carnegie Mellon Pronouncing Dictionary (available via FTP).
• pento, a program to play "Capture Pentominoes," a board game of my own design.
• rot13, a rot13 utility. It also has support for rot-n, where n is any integer, and a Caesar-cipher cracker that uses English letter frequencies.
• split_get, a program for splitting and reassembling binary files. (For example, for transporting large files on multiple floppy disks.)
• tea-example.c, an example of how to use TEA, the Tiny Encryption Algorithm (Wheeler & Needham, 1994). Fixes several typos in Wheeler & Needham's C implementation, and shows one way to give the routines generic wrappers. This encryption algorithm is not adequately secure for real purposes.
• unitrans, a program that converts files between ASCII, UTF-8, UCS-2, and other encodings, including one that's supposed to be supported by the Omega extension of TeX. Wrapper for the uniformats.h (.c) library.

Meta: Programs about programs

• Befunge utilities, including the Fungus virtual machine and its two-dimensional assembler.
• detab, an entab/detab utility.
• Ocamlmerr, a tool for generating nice syntax-error messages from parsers written using the ocamlyacc tool. Inspired by Merr.
• quine, a little program that tries to generate a "quining" function for any given C program. It isn't very robust, in that it expects that all #include directives will be placed first in the file, and that lines generally do not exceed 512 characters. Includes instructions for bootstrapping the quine program's self-quining ability. Can generate 100% portable ISO C quines, with the -c option. There's a less complicated earlier version here.
• usenetify, a utility that understands enough C and C++ to wrap long lines in a manner suitable for Usenet postings or piping to a line printer. Should be used in series with detab.
• usenetify2, a utility that understands C much better than the old usenetify. It also does automatic detabbing. It does not wrap lines as aesthetically as usenetify, but I believe it to be completely free of bugs (unlike the former program).

NetHack patches

• The "sitting" patch combines four YANIs: Joshua Kwan's "pit-sitting" patch, Mark Rae's idea in which very heavy creatures shatter boxes and chests by sitting on them, new interactions when sitting on eggs, and my own YAFM for sitting on a cream pie.
• The "splash" patch causes thrown potions to have effects on objects. You can now blank scrolls by throwing water at them. This patch is compatible with Nephi's invisible objects patch.
• A quick fix for this apparent bug makes the player turn into a stone golem if he becomes a flesh golem while wielding a cockatrice corpse, even if he became a flesh golem by stone-to-fleshing himself.
• The "jargon" patch adds several minor enhancements to the parser. You can now genocide "<foo> mindflayers" and wish for "helmets of <foo>," "royal jelly," and "rubber chickens." Suggestions for more additions are welcomed.
• The "monring" patch allows monsters to use rings somewhat intelligently. For a more complete and spoily rundown, go here.
• This patch implements Simon Tatham's idea that a successful brain-suck by a master mind flayer should cause the castle tune to randomize again. Because, well, it's a Mastermind flayer.
• This patch implements Clint Herron's idea that there should be some way to create new candles for the ascension: reading a non-cursed scroll of light while confused changes all your royal jelly into wax candles. (Well, royal jelly is kind of like wax.)
• This patch [237K, text] doesn't change any game behavior; it just changes a lot of comments in the game's source code, to fix typos, spelling mistakes, grammatical errors, and consistency (e.g., referring to "the Amulet" versus "the amulet"). Totally pointless for anyone except source divers, and pretty pointless for them, too, but now I can say I've read all the comments in NetHack!
• This patch implements Joe Clark's idea that "an emerald ring" be reported as "a green stone ring" until emeralds are actually identified. I personally wouldn't use this patch, though; it unbalances wizards without adding anything new in the way of gameplay.
• The "xorn" patch fixes a few bugs that will undoubtedly get fixed in the next version of NetHack: you can't engrave while embedded in rock; fixed message for writing underwater; trying to dig messes up engravings; and fixed messages for casting Protection in funny places.
• The "wish" patch allows the player to wish for "the gnome's aklys" and get it. (Wizards can wish for "Brad's pit".) It also refactors the wishing code a little bit. This is probably full of bugs.

Snippets

• AlphaBeta.hh, a C++ template class implementing depth-first search, alpha-beta search, and breadth-first search on an arbitrary game tree.
• ctemplates, a demonstration of how to create a "template class" in standard C.
• aplencode, a program that reads an APL program in Jim Weigang's "APL-ASCII" notation and writes it back out in UTF-8. Somewhat useful for typesetting APL with TeX.
• bitap, an implementation of the bitap algorithm for fuzzy string searching.
• cartouche, a hack perpetrated for Shawn Knight's Egyptology class in 2004. Self-documenting.
• dance, a C implementation of Donald Knuth's "Dancing Links" algorithm. Includes an application to the solving of Sudoku puzzles.
• greekana, a program that produces all the words in a dictionary that are anagrams of Greek letters, as described in this rec.puzzles post.
• imagetour, a program that draws a visual representation of a Traveling Salesman tour. I used it to make lena-tour.png, after feeding the "Lena" image through randtsp and a TSP solver.
• pangram, a program that generates self-inventorying sentences by Robinsonizing.
• randtsp, a program that generates input to the TSP solver according to a given grayscale image. See imagetour.
• A unit cell [PNG] for simulating Rule 110 in Wireworld. [RLE source]
• sirds_hider, a program that hides "secret messages" in SIRDS stereograms, as described in sci.crypt in July 2004.