Landon Curt Noll
0bc6c3e413
We quasi-canonicalized markdown links to FAQ entries. **IMPORTANT NOTE**: This is a useful step in completing issue #2417. This commit is consistent with the top level TODO comment requirements. Nevertheless, this changes made by this commit needs to be examined and in some cases improved. A link to an FAQ entry is of the form: ``` FAQ on "[the link text](....faq.html#string)" FAQ on "[the link text](....faq.html#string)" ``` The "FAQ" is at the start of the line, or in rare cases is preceded only by whitespace. The reference to the FAQ starts outside of the markdown link with the string **FAQ ON "**. After the markdown link is a **"** followed by either the end of line or a single punctuation character such as a period or comma. We reduced the size of "the link text" that refer to an FAQ to at most 3 words. In some cases the sentence and/or text surrounding the markdown link to a FAQ may need to be further adjusted to better accommodate this new style. **IMPORTANT NOTE**: References to a FAQ entry are on a separate line. p.s. When linking to the `faq.html` file itself, we use markdown of the form "`the [IOCCC FAQ](..../faq.html)`" and place the word "the" outside of the "IOCCC FAQ" link text. Given the above system (and because references to an FAQ entry is on a separate line), the following command shows links to FAQ entries, sorted by FAQ entry "link #name" so that one may evaluate the way a given FAQ entry is referenced: ```sh find * -name '*.md' -print0 | xargs0 grep -E '^[[:space:]]*FAQ on "' | sed -e 's/^\([^:]*\):\( *FAQ on "[^#]*\)#\([^)]*\)\()".*\)$/#\3\t\1\t\2#\3\4/' | sort ``` The above command shows the value of consistency when it comes to FAQ references. **NOTE**: There are a few differences on how a given FAQ is references. That is probably OK as there is NOT an "total mandate" that all references to a given FAQ must have the same "link text" for example. On the other hand if references to a given FAQ can be identical, that might be helpful. We are certain that in some contexts the "link text" might need to change. Should we decide to change the way FAQ are referenced, we will be able to modify identify and modify them with greater ease.' Examine the changes made by this commit and adjust and/or improve as needed. Performed `make www` to accomplish the above and to test under macOS.
To build:
make
To use:
./prog
Try:
On a terminal that supports 24 bit color, has black background, and size at least 125x38, try:
./try.sh
Judges' remarks:
It is said by some students of Astronomy:
Oh, Be A Fine Gal, Kiss Me!
Oh, Be A Fine Gentleman, Kiss Me!
Many Mnemonic variations exist. You might wish, on a star, to better understand the colors being displayed. And those in the deep south might wish to go north for a better view.
Author's remarks:
How to build:
cc -o prog -std=gnu11 -O3 prog.c
or
make
Poster:
You can generate an A3 sized poster by make docs. This command creates a pdf file poikola.pdf.
Introduction:
It was a starry night when my wife pointed her finger up and asked: "What is this star and may I have some Easter eggs?"
So I had to sit down and solve those tricky questions with Nano and a C compiler.
NOTICE to those who wish for a greater challenge:
If you want a greater challenge, don't read any further: just try to understand the program via the source.
If you get stuck, come back and read below for additional hints and information.
Little hints:
Basically, the program draws animated ASCII art of the Big Dipper using Annie Jump Cannon's spectral classification system of stars and I think the colors of the output are as accurate as possible.
This program also tells once in a year if it is correct time to find and eat some Easter eggs.
The program has also at least three other functions, obvious and not so obvious.
Technical jargon
This program has been tested on xterm and Konsole and also Linux virtual terminal. Color support in the terminal is not necessary, but the effect is better with it.
This entry has partial support for terminals with a white background but the best viewing experience is achieved when the terminal in use supports 24-bit colors, has a black background and the size is at least 125x38.
Special note for Mac users: Terminal.app does not work as expected; you might
need xterm from XQuartz, see
FAQ on "X11 on macOS",
or some other working
terminal. Thanks to Dave Burton for spotting this
problem.
The main reason for the header unistd.h is getdelim(3) but once I included it
I also abused other functions and #defines. This header is mutually exclusive
with -std=c11.
The program was developed with little-endian machines; I tried to support big-endian too, but this support is somewhat limited.
This program has been compiled with:
- i386 (Debian Stretch) with gcc and clang
- amd64 (Debian Buster) with gcc and clang
- Raspberry Pi 3 (Debian stretch) with gcc and clang
- Lego Mindstorms EV3 Intelligent Brick (Debian Jessie) with gcc and clang (in this case, compiling time with clang-3.5 12 seconds and with gcc 27 seconds)
Extra notes from the judges on the macOS Terminal.app problems:
Depending on the settings of the terminal in Terminal.app the program might not show anything at all. In other cases it won't show all the colours right but mostly is okay. YMMV, as they say.
Warnings and restrictions required by law:
Please do not feed little babies chocolate.
Major hints:
I incorporated the Fletcher 16 checksum algorithm into the source for security reasons; it might be challenging to make changes without breaking the main functionality of the code.
The space after #define p return is necessary.
The computus (method to determine the date of Easter) uses an algorithm described in the journal Nature in 1876. It should be valid for Gregorian calendars.
Some obfuscation techniques used:
- I tried to use meaningless or misleading variable names. For example, this
program draws the Big Dipper with the correct colors, but variables like
o,b, andaare used in totally unrelated tasks. - I reused and recycled variables almost every time when possible.
- Unnecessary use of predefined stuff like
__ATOMIC_SEQ_CST. - When I was a kid, my favorite programming language was Pascal. In Pascal,
there are things like
begin;andend;instead of curly brackets. They are used also in my code, but I had to shorten them to meet size requirements. - I also have strong Perl background, and therefore I added some dollar signs
to the code. One of the first ideas was to write all variables with prefixed
$, but then I rejected it.
If you think you understand how this program works, can you answer these questions:
- What is the value of
aI_after line 21? - Why are there some big numbers on line 47?
- How is the scaling effect created?
- How do you change a single bit, without changing the functionality?
Rot18 part
Because the rot13 is too easy to decode with the plain eyes, I decided to use the Caesar cipher with the key 18:
Lzw xajkl tsffwj ak wfugvwv mkafy AWWW 754 xdgslk gf dafw 47. Al ak hjaflwv
gfdq gf dalldw-wfvasf esuzafwk.
If you want to or must know and don't know how to decipher this, you might look at the Caesar cipher decoder. Find the text that says:
Manual decryption and parameters
Shift/Key (number)
and enter 18 and then click the button that says: DECRYPT (BRUTEFORCE).