PiE in the sky award

Yusuke Endoh
mame@ruby-lang.org
https://github.com/mame/

Judges' comments:

To build:

make endoh2

To run:

./endoh2 > pi.c
gcc -o pi pi.c
./pi > 314.c
...

./endoh2 e > e.c  
gcc -o e e.c
./e > 271.c
...

Try:

make pi
make e
make everything

Selected Judges Remarks:

A pi/e printing quasi-quine in ASCII art with a compressed font in it; what else to wish for in this program? Virtual machine emulation?

Author’s comments:

Yeah, “Again”. Sorry. But I don’t feel guilty or uncomfortable.

This entry is based on ‘over-used themes’ such as self reproducing program and pi or e computation. I know you’re tired of them.

But have you ever seen all-in-one?

What it is

This program generates a new program in the shape of the Greek letter pi. Then, the generated program:

computes 3 digits of pi and prints it as a ASCII-art program that:
computes 4 digits of pi and prints it as a ASCII-art program that:
computes 5 digits of pi and prints it as a ASCII-art program that:
computes 6 digits of pi and prints it as a ASCII-art program that:
etc.

One more thing… When you give a command line option “e” to the first program, the generated one will compute Napier’s constant rather than pi.

Obfuscation

This program itself is in the shape of a spigot. This is derived from analogy with “spigot algorithm” which infinitely computes the value of a mathematical constant such as pi or e.

http://en.wikipedia.org/wiki/Spigot_algorithm

The two sets of programs, 314*.c and 271*.c, are almost the same except its shape and constant computation part. I tailored the common part to parse in both shapes (“3.14…” and “2.71…”), by tweaking the computation order and adding meaningless code fragment.

On the other hand, to make it fit inside one screen (80 x 25), my program is shortened properly, more than it looks. (As you may know, Quine needs to make its program size doubled.) For example, this program involves 3x5 bitmap font data of ten characters (‘0’ – ‘9’), as just 20 bytes: “G1%xJ{;Q7wunmuGuu%uu”. We can decode character n as 275*s[n+10] - 8*s[n] - 8. I solved the system of Bezout’s identities to find the magic string, with the aid of a brute force. See find-font-table.rb in detail.

http://en.wikipedia.org/wiki/B%C3%A9zout's_identity

I used many other tricks for short coding.

I’m sorry that many ASCII-art-style winning entries of IOCCCs ignore preprocessor directives. In my program, #include is a part of ASCII-art with comment padded.

These design requirements made my program well-obfuscated willy-nilly.

Portability

I expect it to work in any major environment and C compiler. To build with no warning, it requires two C99 features: string literal more than 509 characters and omissible return in main function. In fact, recent compilers with “-std=c99 -Wall -W -Wextra -pedantic” would say nothing.

gcc -std=c99 -Wall -W -Wextra -pedantic spigot.c
clang -std=c99 -Wall -W -Wextra -pedantic spigot.c

I’ve tested with gcc-4.6.3 and clang-3.0 on Linux (Ubuntu 12.04) and gcc-4.5.3 and clang-3.1 on Cygwin.

Synopsis

gcc endoh2.c -o endoh2

./endoh2 > pi.c
cat pi.c

gcc pi.c     -o pi     ; ./pi     > 314.c     ; cat 314.c
gcc 314.c    -o 314    ; ./314    > 3141.c    ; cat 3141.c
gcc 3141.c   -o 3141   ; ./3141   > 31415.c   ; cat 31415.c
gcc 31415.c  -o 31415  ; ./31415  > 314159.c  ; cat 314159.c
gcc 314159.c -o 314159 ; ./314159 > 3141592.c ; cat 3141592.c
etc...

./endoh2 e > e.c
cat e.c

gcc e.c      -o e      ; ./e      > 271.c     ; cat 271.c
gcc 271.c    -o 271    ; ./271    > 2718.c    ; cat 2718.c
gcc 2718.c   -o 2718   ; ./2718   > 27182.c   ; cat 27182.c
gcc 27182.c  -o 27182  ; ./27182  > 271828.c  ; cat 271828.c
gcc 271828.c -o 271828 ; ./271828 > 2718281.c ; cat 2718281.c
etc...

You can do make everything for the process (with no cat).

Note: The executable may return a failure (non-zero) exit status unless -std=c99 option is given.