ioccc/1990/dg/README.md at 8125a24fdbef3ca4c38f2a022df4291f6f2b1463

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Landon Curt Noll 3ddbac9e6b improve how markdown code language is commented

We added a space between the markdown triple code mark
and language that was enclosed in HTML comments.

So a line of the form:

````
```<!---c--->
````

became:

````
``` <!---c--->
````

This was done to **help** some code see that the HTML comment
string was not a markdown code specifier.   Not all code
understands this after this changed.  For example, `pandoc(1)`
still forms HTML classes of the form "&lt;!---c--&gt;"
when it encounters the above mentioned change.

We also fixed a problem with `2019/dogon/README.md` regarding
a markdown code block.

We also fixed a problem with `2020/yang/README.md` regarding
a markdown code block.

2024-04-12 11:45:50 -07:00

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To build:

    make all

To use:

    echo foo bar | ./dg

Try:

    ./try.sh

Judges' remarks:

Some C preprocessors got confused about single quotes in certain cases. In particular, the following source line:

    b12(ase(bco(acp(bi(acp(bcp(acp(bpl(aqu(bqu(A))))))))))))))))))))))))))))))

sometimes has to be changed to:

    b12(ase(bco(acp(bi(acp(bcp(acp(bpl('A'))))))))))))))))))))))))))))

particularly if the C preprocessor botches single quotes in cpp expansions, which we have done for the wider audience.

Author's remarks:

If my preprocessor could hack it, I could write this as one single line rather than 4, but when I do that I get a complaint "defines nested too deeply".

Obfuscation spoiler:

This is another rot13 job (believe it or not) - the #defines are a novel way of adding tokens: #define b12(x) 12 x means that at some point in the source a 12 is followed by the compressed nested #defines. The b12 gets the previous compression as an argument, and prepends the 12, thus making another step in the recreation of the source. The axx() #defines do the same, but add tokens after.

As for the rot13 algorithm, it relies on index(3) to find if the character is in the set A-Za-z. l[] is an array that gets filled with:

    "nopqrstuvwxyzzzzabcdefghijklmmmmNOPQRSTUVWXYZZZZABCDEFGHIJKLMMMM"

If index(3) says the char is in the alphabet, then XOR the offset with 16 to translate, and output, otherwise pass it unchanged.

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