Landon Curt Noll
4ee4c731f7
While not strictly necessary, replacing the two ASCII tab characters in the markdown copyright comment makes it easier to detect problematic TAB indentation within markdown files. After this commit, only 90 markdown files have leading ASCII TAB characters. And again, while not strictly necessary, we can consider running expand on those 90 markdown files to see what effect that might have on the HTML files they produce. Replace leading ASCII TAB characters with multiples of 8 ASCII SPACE characters (the default action of the `expand(1)` tool) might have an negative effect on some HTML formatting where **hack-a-round** formatting was attempted to fix broken indentation caused by problematic ASCII TAB characters. Think of this as a baseline for evaluating leading TAB characters within markdown files. TODO: Consider either using `expand(1)` to replace leading ASCII TAB characters with multiples of 8 ASCII SPACE characters AND/OR modifying the appropriate `bin` tool to convert leading ASCII TAB characters into multiples of 8 ASCII SPACE characters.
To build:
make all
To use:
./dorssel
# input some text
echo text | ./dorssel
Try:
./try.sh
Judges' remarks:
How does the program decide which way to convert?
What obsolescent feature are we talking about? (No, it's not a C language feature.)
The author suggests that you try to answer the following questions:
-
Which character in the initializing string is totally irrelevant?
-
Which two relevant characters in the initializing string may be exchanged without altering the behavior?
-
Which characters in the initializing string are somewhat irrelevant, and to what values may they be changed without altering the behavior?
-
Which characters may be used to enlarge the initializing string by one without altering the behavior ?
Extra credit:
Try doing what the last part of the last command in try.sh suggests. As in, do the following:
echo ". -..- . .-. -.-. .. ... .
-.-. .... .- -. --. . - .... . .--. .-. --- --. .-. .- -- ... --- .. - -.. --- . ... -. --- - ... .... --- ..- -" | ./dorssel
and make the necessary adjustments.
You might also want to read the dorssel.html file.
Author's remarks:
Usage
This program converts ASCII to Morse code, and vice versa.
The program reads in lines from standard input and writes its result to standard output. The direction of conversion is determined on a per line basis. Each line must consist of a maximum of 952 characters followed by a new line character and they must not contain any NUL characters. Otherwise, some characters may be lost in the conversion.
-
Encoding to Morse code: The program knows the Morse codes for all Latin letters (a-z, case insensitive) and decimal digits (0-9). Any other characters are replaced by an ASCII space,
' '. Morse code per converted character is written as a sequence of.and-characters, each sequence followed by a space. -
Decoding from Morse code: Morse code should be typed as sequences of
.and-characters, separated by a space. Extra spaces will be echoed back (to separate words). Unknown sequences will be converted to a?character.
Notes
The program assumes both source and execution character sets to be ASCII. As far as I can tell, the program is conforming and does not invoke undefined behavior.
Hints
Try:
./dorssel < dorssel.c | ./dorssel
to see what variables, numbers, and functions are used. (Does a better job than most C beautifiers).
- Filter your text twice (as in the previous sample) to obtain a version of your text that can be reversibly Morsified, i.e.
./dorssel < dorssel.c | ./dorssel | ./dorssel | ./dorssel
is the same as
./dorssel < dorssel.c | ./dorssel
- The file dorssel.html contains all the information needed to understand this program. For an obfuscated spoiler, try
./dorssel < dorssel.md