Update 1989 winning entries' README.md files
Format and typo fixes.
This commit is contained in:
Cody Boone Ferguson committed
1 parent
15787fbdd3
commit
f458d5aefe
9 files changed
+281
-193
No files matched your search
+22
-15
@@ -1,40 +1,47 @@
|
||||
# Best self-modifying program
|
||||
|
||||
Jay Vosburgh
|
||||
Sequent Computer Systems, Inc
|
||||
15450 SW Koll Parkway
|
||||
Beaverton, OR
|
||||
97006
|
||||
USA
|
||||
Jay Vosburgh
|
||||
Sequent Computer Systems, Inc
|
||||
15450 SW Koll Parkway
|
||||
Beaverton, OR
|
||||
97006
|
||||
USA
|
||||
|
||||
## To build:
|
||||
|
||||
make all
|
||||
```sh
|
||||
make all
|
||||
```
|
||||
|
||||
[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) got this to work with
|
||||
modern systems. Thank you Cody for your assistance!
|
||||
|
||||
|
||||
## To run
|
||||
## To run:
|
||||
|
||||
./fubar number>
|
||||
```sh
|
||||
./fubar <number>
|
||||
```
|
||||
|
||||
## Try:
|
||||
|
||||
./fubar 2
|
||||
```sh
|
||||
./fubar 2
|
||||
```
|
||||
|
||||
|
||||
## Judges' remarks
|
||||
## Judges' remarks:
|
||||
|
||||
Run this with a single digit argument (or wait a long time).
|
||||
|
||||
The blank line at the beginning of the source is mandatory.
|
||||
Do you know why?
|
||||
|
||||
NOTE: don't try running `ouroboros.c` directly with an arg as it'll turn into an
|
||||
infinite loop. The same will happen with larger numbers.
|
||||
NOTE: don't try running [ouroboros.c](ouroboros.c) (note that it's executable)
|
||||
directly with an arg as it'll turn into an infinite loop. The same will happen
|
||||
with larger numbers.
|
||||
|
||||
## Author's remarks
|
||||
## Author's remarks:
|
||||
|
||||
In a nutshell, this is probably the slowest and most
|
||||
obnoxious factorial program ever written. Unfortunately,
|
||||
@@ -46,7 +53,7 @@ The shell script compiles itself, and then executes the
|
||||
resulting binary, giving the source as input. The program
|
||||
works by successively modifying #define lines each pass through.
|
||||
|
||||
Both "indent" and "cb" will damage the program, "indent"
|
||||
Both `indent` and `cb` will damage the program, `indent`
|
||||
much more so.
|
||||
|
||||
## Copyright and CC BY-SA 4.0 License:
|
||||
|
||||
+18
-12
@@ -1,34 +1,40 @@
|
||||
# Strangest abuse of the rules
|
||||
|
||||
Jari Arkko
|
||||
Laboratory of Information Processing Science
|
||||
Helsinki University of Technology
|
||||
Otakaari 1
|
||||
02150 Espoo
|
||||
Finland
|
||||
Jari Arkko
|
||||
Laboratory of Information Processing Science
|
||||
Helsinki University of Technology
|
||||
Otakaari 1
|
||||
02150 Espoo
|
||||
Finland
|
||||
|
||||
## To build and run:
|
||||
|
||||
make clobber all
|
||||
```sh
|
||||
make clobber all
|
||||
```
|
||||
|
||||
## Judges notes:
|
||||
## Judges' remarks:
|
||||
|
||||
On many systems the compiler will not allow you to send the object file to
|
||||
/dev/tty. The author suggested:
|
||||
|
||||
cc -c -o /dev/tty jar.1.c
|
||||
```sh
|
||||
cc -c -o /dev/tty jar.1.c
|
||||
```
|
||||
|
||||
On systems that have symbolic links, we suggest:
|
||||
|
||||
ln -s /dev/tty jar.1.o
|
||||
cc -c jar.1.c
|
||||
```sh
|
||||
ln -s /dev/tty jar.1.o
|
||||
cc -c jar.1.c
|
||||
```
|
||||
|
||||
As a last resort the scripts provided simply cat the .o file to the terminal.
|
||||
|
||||
Abuse of the rules winners usually result in a change of the rules. Starting in
|
||||
1990, compiling entries must result an regular file which can be executed.
|
||||
|
||||
## Selected notes from the author:
|
||||
## Author's remarks:
|
||||
|
||||
This program is (supposedly) the smallest C program able to print "Hello
|
||||
world.". The compilation itself produces the desired printout and the program
|
||||
|
||||
+40
-18
@@ -1,33 +1,41 @@
|
||||
## Best of show
|
||||
|
||||
Jari Arkko, Ora Lassila, Esko Nuutila
|
||||
Laboratory of Information Processing Science
|
||||
Helsinki University of Technology
|
||||
Otakaari 1
|
||||
02150 Espoo
|
||||
Finland
|
||||
Jari Arkko, Ora Lassila, Esko Nuutila
|
||||
Laboratory of Information Processing Science
|
||||
Helsinki University of Technology
|
||||
Otakaari 1
|
||||
02150 Espoo
|
||||
Finland
|
||||
|
||||
## To build:
|
||||
|
||||
make all
|
||||
```sh
|
||||
make all
|
||||
```
|
||||
|
||||
[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed this to work with
|
||||
modern compilers. Modern compilers do not allow code like:
|
||||
|
||||
#define D define
|
||||
#define a include
|
||||
```c
|
||||
#define D define
|
||||
#define a include
|
||||
|
||||
#D foo bar
|
||||
#a <stdio.h>
|
||||
#D foo bar
|
||||
#a <stdio.h>
|
||||
```
|
||||
|
||||
He notes that there _is_ a way to get it (or something close to it) to work. Do
|
||||
you know how?
|
||||
|
||||
Thank you Cody for your assistance!
|
||||
|
||||
|
||||
## To run:
|
||||
|
||||
|
||||
./jar.2
|
||||
[enter some lisp]
|
||||
```sh
|
||||
./jar.2
|
||||
[enter some lisp]
|
||||
```
|
||||
|
||||
NOTE: this entry will likely segfault on invalid input.
|
||||
|
||||
@@ -40,15 +48,27 @@ all this functionality in such a small, densely packed program,
|
||||
is impressive enough to win the Best of show award.
|
||||
|
||||
|
||||
## Selected notes from the author:
|
||||
## Author's remarks:
|
||||
|
||||
This program implements a Lisp interpreter in 1465 bytes of source.
|
||||
Some sophisticated features supported, eg. functionals and recursion.
|
||||
The special-forms/functions/variables implemented are:
|
||||
|
||||
+ - * < ()
|
||||
car cdr cons defun equal
|
||||
function if lambda quote t
|
||||
- \+
|
||||
- \-
|
||||
- \*
|
||||
- \<
|
||||
- ()
|
||||
- car
|
||||
- cdr
|
||||
- cons
|
||||
- defun
|
||||
- equal
|
||||
- function
|
||||
- if
|
||||
- lambda
|
||||
- quote
|
||||
- t
|
||||
|
||||
Below are sample lisp expressions you might choose to try as input.
|
||||
The program implements a conventional lisp listener, i.e. you type in
|
||||
@@ -56,6 +76,7 @@ lisp expressions (followed by CR), the program evaluates them and
|
||||
prints out the return values. End execution by typing an end-of-file
|
||||
character.
|
||||
|
||||
```lisp
|
||||
(+ 2.5 3.1)
|
||||
(defun fib (n)
|
||||
(if (< n 2)
|
||||
@@ -74,6 +95,7 @@ character.
|
||||
(cons (quote (f)) ())
|
||||
(car (quote (a b c)))
|
||||
(cdr (cdr (quote (g h i))))
|
||||
```
|
||||
|
||||
|
||||
Please do not leave any whitespace before the first parenthesis when
|
||||
|
||||
+16
-12
@@ -1,20 +1,24 @@
|
||||
## Most complex algorithm
|
||||
|
||||
Paul E. Black
|
||||
CIRRUS LOGIC, Inc.
|
||||
1463 Centre Pointe Dr.
|
||||
Milpitas, CA
|
||||
95035
|
||||
USA
|
||||
Paul E. Black
|
||||
CIRRUS LOGIC, Inc.
|
||||
1463 Centre Pointe Dr.
|
||||
Milpitas, CA
|
||||
95035
|
||||
USA
|
||||
|
||||
## To build:
|
||||
|
||||
make all
|
||||
```sh
|
||||
make all
|
||||
```
|
||||
|
||||
|
||||
## Try:
|
||||
|
||||
./paul
|
||||
```sh
|
||||
./paul
|
||||
```
|
||||
|
||||
[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed a segfault under
|
||||
macOS. The problem was that the int (from `#define f`) should be a long. This
|
||||
@@ -31,9 +35,9 @@ removing the trailing "\" on line 12 and joining lines 12 and
|
||||
WHAT FOLLOWS IS A DETAILED PROGRAM EXPLANATION AND SPOILER.
|
||||
IF YOU WANT A REAL CHALLENGE, DON'T READ ANY FURTHER AND TRY
|
||||
TO UNDERSTAND THE PROGRAM VIA THE SOURCE.
|
||||
|
||||
|
||||
Selected notes from the author:
|
||||
|
||||
## Author's remarks:
|
||||
|
||||
This programs computes and prints Fibonacci numbers by
|
||||
simulating a Turing machine with the proper program.
|
||||
@@ -78,8 +82,8 @@ If bit 4 (16&byte) is true, the next character is sent to
|
||||
stdout. (I added this feature so programs could print
|
||||
results.)
|
||||
|
||||
The Turing machine has next state 'j' when it begins. The
|
||||
cycle is 1) exit if the state is 'x', 2) find the next
|
||||
The Turing machine has next state `j` when it begins. The
|
||||
cycle is 1) exit if the state is `x`, 2) find the next
|
||||
instruction (given the state and the character under the scan
|
||||
head). [The program string is searched forward for the next
|
||||
matching instruction. If the end of the string is reached, the
|
||||
|
||||
+30
-21
@@ -1,15 +1,17 @@
|
||||
## Best minimal use of C
|
||||
|
||||
Arch D. Robison
|
||||
University of Illinois
|
||||
1304 W. Springfield Ave.
|
||||
Urbana, IL
|
||||
61801
|
||||
USA
|
||||
Arch D. Robison
|
||||
University of Illinois
|
||||
1304 W. Springfield Ave.
|
||||
Urbana, IL
|
||||
61801
|
||||
USA
|
||||
|
||||
## To build:
|
||||
|
||||
make all
|
||||
```sh
|
||||
make all
|
||||
```
|
||||
|
||||
|
||||
NOTE: we were able to get this to compile under modern systems with a patch from
|
||||
@@ -18,24 +20,27 @@ Yusuke!
|
||||
|
||||
## To run:
|
||||
|
||||
./robison
|
||||
# enter valid expressions
|
||||
|
||||
```sh
|
||||
./robison
|
||||
# enter valid expressions
|
||||
```
|
||||
|
||||
## Try:
|
||||
|
||||
./robison
|
||||
11x10
|
||||
```sh
|
||||
./robison
|
||||
11x10
|
||||
|
||||
echo 1x10x111 | ./robison
|
||||
echo 1x10x111 | ./robison
|
||||
|
||||
echo 1+1+10 | ./robison
|
||||
echo 1+1+10 | ./robison
|
||||
|
||||
echo 100 - 1 | ./robison
|
||||
echo 100 - 1 | ./robison
|
||||
|
||||
echo -100 x 100 + 1 | ./robison
|
||||
echo -100 x 100 + 1 | ./robison
|
||||
|
||||
echo 100 / 100 | ./robison # <-- what happens here ?
|
||||
echo 100 / 100 | ./robison # <-- what happens here ?
|
||||
```
|
||||
|
||||
NOTE: this entry will crash with numbers with non binary digits.
|
||||
|
||||
@@ -50,7 +55,7 @@ constructs that the C language supports.
|
||||
NOTE: this entry will likely dump core with invalid input.
|
||||
|
||||
|
||||
## Selected notes from the author:
|
||||
## Author's remarks:
|
||||
|
||||
This program is a handy picoAPL interpreter written in C--. It
|
||||
outputs the evaluation of an APL expression from standard
|
||||
@@ -58,13 +63,17 @@ input. Functions are limited to dyadic +,-,x, and unary -;
|
||||
numerals must be binary. Parentheses may be used for
|
||||
grouping. For example:
|
||||
|
||||
101x111-100
|
||||
```
|
||||
101x111-100
|
||||
```
|
||||
|
||||
prints:
|
||||
|
||||
1111
|
||||
```
|
||||
1111
|
||||
```
|
||||
|
||||
That is 5x(7-4) is 15. (APL groups from right to left.)
|
||||
That is `5x(7-4)` is `15`. (APL groups from right to left.)
|
||||
Extending it to the full APL language should be trivial.
|
||||
|
||||
The C-- language improves the C language by removing superfluous
|
||||
|
||||
+14
-11
@@ -1,34 +1,37 @@
|
||||
## Best layout
|
||||
|
||||
Lievaart, Roemer B.
|
||||
VU-Informatica, Amsterdam
|
||||
Marcusstraat 29/2,
|
||||
NL 1091 TJ Amsterdam
|
||||
Netherlands
|
||||
Lievaart, Roemer B.
|
||||
VU-Informatica, Amsterdam
|
||||
Marcusstraat 29/2,
|
||||
NL 1091 TJ Amsterdam
|
||||
Netherlands
|
||||
|
||||
## To build:
|
||||
|
||||
make all
|
||||
```sh
|
||||
make all
|
||||
```
|
||||
|
||||
## Try:
|
||||
|
||||
./roemer
|
||||
```sh
|
||||
./roemer
|
||||
```
|
||||
|
||||
## Judges' remarks:
|
||||
|
||||
Do you know what this program does? If you do, look again,
|
||||
there is more here than meets the PI.
|
||||
|
||||
## Selected notes from the author:
|
||||
## Author's remarks:
|
||||
|
||||
Passes lint, but not with the strictest options, for it
|
||||
contains some "null-statements", as well two identifiers
|
||||
which are, if compilers only take 6 characters, the same. It
|
||||
also uses write(2), so not totally system independent.
|
||||
|
||||
You are very much invited to pass this program through a
|
||||
C-beautifier. (First strip newlines and tabs, if your cb can't
|
||||
do that.)
|
||||
You are very much invited to pass this program through a C-beautifier. (First
|
||||
strip newlines and tabs, if your `cb` can't do that.)
|
||||
|
||||
## Copyright and CC BY-SA 4.0 License:
|
||||
|
||||
|
||||
+58
-46
@@ -1,15 +1,16 @@
|
||||
# Best game
|
||||
|
||||
John Tromp
|
||||
Centre for Mathematics and Computer Science (CWI)
|
||||
Oetgensstraat 7
|
||||
1701CK Heerhugowaard
|
||||
Netherlands
|
||||
John Tromp
|
||||
Centre for Mathematics and Computer Science (CWI)
|
||||
Oetgensstraat 7
|
||||
1701CK Heerhugowaard
|
||||
Netherlands
|
||||
|
||||
## To build:
|
||||
|
||||
make all
|
||||
|
||||
```sh
|
||||
make all
|
||||
```
|
||||
|
||||
We used a patch from [Yusuke Endoh](/winners.html#Yusuke_Endoh)
|
||||
to get this to compile under gcc. Thank you Yusuke for your assistance!
|
||||
@@ -24,6 +25,40 @@ being created) and after this making sure the terminal stayed sane (the letter
|
||||
high score file was reinstated). We thank you for your assistance Cody (he
|
||||
cynically notes that he did it because tetris just has to work)!
|
||||
|
||||
## To run:
|
||||
|
||||
```sh
|
||||
./tromp [drops_per_sec [cmd_string]]
|
||||
```
|
||||
|
||||
## Try:
|
||||
|
||||
```sh
|
||||
./tromp 5
|
||||
|
||||
# fast with vim keys
|
||||
# h - left (left)
|
||||
# k - rotate (arbitrary, in vim k = up)
|
||||
# l - right (right)
|
||||
# j - drop (down)
|
||||
# space - pause (literal space in vim)
|
||||
# q - quit (similar to :q in vim)
|
||||
|
||||
./tromp 10 "hklj q"
|
||||
```
|
||||
|
||||
NOTE: after this game ends a file called `HI` will be in the directory with the
|
||||
high scores (up to 20 runs saved) so one can see who has the highest score. The
|
||||
file might look like:
|
||||
|
||||
```
|
||||
330 by cody
|
||||
136 by cody
|
||||
```
|
||||
|
||||
.... hey, I haven't played in a very long time and the lower one was hitting
|
||||
space (default drop) in rapid succession :-)
|
||||
|
||||
|
||||
### Alternate code:
|
||||
|
||||
@@ -32,39 +67,14 @@ were unable to see the improvements in modern systems even after fixing it to
|
||||
compile (the high score file was not created at all) but if you have an old
|
||||
compiler you can try compiling it in its original unmodified form by running:
|
||||
|
||||
make alt
|
||||
```sh
|
||||
make alt
|
||||
```
|
||||
|
||||
Use `tromp.alt` as you would `tromp` above.
|
||||
|
||||
|
||||
## To run:
|
||||
|
||||
./tromp [drops_per_sec [cmd_string]]
|
||||
|
||||
## Try:
|
||||
|
||||
./tromp 5
|
||||
|
||||
# fast with vim keys
|
||||
# h - left (left)
|
||||
# k - rotate (arbitrary, in vim k = up)
|
||||
# l - right (right)
|
||||
# j - drop (down)
|
||||
# space - pause (literal space in vim)
|
||||
# q - quit (similar to :q in vim)
|
||||
./tromp 10 "hklj q"
|
||||
|
||||
NOTE: after this game ends a file called `HI` will be in the directory with the
|
||||
high scores (up to 20 runs saved) so one can see who has the highest score. The
|
||||
file might look like:
|
||||
|
||||
|
||||
330 by cody
|
||||
136 by cody
|
||||
|
||||
|
||||
.... hey, I haven't played in a very long time and the lower one was hitting
|
||||
space (default drop) in rapid succession :-)
|
||||
|
||||
## Judges' remarks
|
||||
## Judges' remarks:
|
||||
|
||||
This is a character terminal version of the TETRIS program.
|
||||
It runs on a VT100 compatible terminal or emulator. It is
|
||||
@@ -75,23 +85,23 @@ will drop in a second, is 2. The default "cmd_string" is
|
||||
"jkl pq". The first 6 characters of "cmd_string" relate
|
||||
to the following 6 game commands:
|
||||
|
||||
j - left
|
||||
k - rotate
|
||||
l - right
|
||||
<space> - drop
|
||||
p - pause
|
||||
q - quit
|
||||
- j - left
|
||||
- k - rotate
|
||||
- l - right
|
||||
- space - drop
|
||||
- p - pause
|
||||
- q - quit
|
||||
|
||||
Specifying "cmd_string" allows one to re-define the commands.
|
||||
The pause command pauses the game, clears the screen and
|
||||
prints the current score. To un-pause, type the pause
|
||||
prints the current score. To resume, type the pause
|
||||
character again, which by default is "p".
|
||||
|
||||
As was stated last year, we are likely to be more strict about
|
||||
portability in the future. [ We mean it this time :-) ]
|
||||
|
||||
|
||||
## Author's remarks
|
||||
## Author's remarks:
|
||||
|
||||
This program plays the familiar game of `TETRIS' with the
|
||||
following features:
|
||||
@@ -131,6 +141,7 @@ at the start and -raw at the end. This further reduces the size of
|
||||
the program, but has the possible disadvantage that the program
|
||||
can only by stopped by 'q' or by the `kill -9' command.
|
||||
|
||||
```c
|
||||
long h[4];t(){h[3]-=h[3]/3000;setitimer(0,h,0);}c,d,l,v[]={(int)t,0,2},w,s,I,K
|
||||
=0,i=276,j,k,q[276],Q[276],*n=q,*m,x=17,f[]={7,-13,-12,1,8,-11,-12,-1,9,-1,1,
|
||||
12,3,-13,-12,-1,12,-1,11,1,15,-1,13,1,18,-1,1,2,0,-12,-1,11,1,-12,1,13,10,-12,
|
||||
@@ -150,6 +161,7 @@ can only by stopped by 'q' or by the `kill -9' command.
|
||||
0);while(getchar()-a[4]);puts("\033[H\033[J\033[7m");sigsetmask(s);}}d=popen(
|
||||
"stty -cbreak echo stop \023;sort -mnr -o HI - HI;cat HI","w");fprintf(d,
|
||||
"%4d from level %1d by %s\n",w,l,getlogin());pclose(d);}
|
||||
```
|
||||
|
||||
## Copyright and CC BY-SA 4.0 License:
|
||||
|
||||
|
||||
+14
-10
@@ -1,21 +1,25 @@
|
||||
## Best one liner
|
||||
|
||||
David Van Brackle
|
||||
Department of Computer Science
|
||||
University of Central Florida
|
||||
Orlando, Florida
|
||||
32816
|
||||
USA
|
||||
David Van Brackle
|
||||
Department of Computer Science
|
||||
University of Central Florida
|
||||
Orlando, Florida
|
||||
32816
|
||||
USA
|
||||
|
||||
|
||||
## To build:
|
||||
|
||||
make all
|
||||
```sh
|
||||
make all
|
||||
```
|
||||
|
||||
## Try:
|
||||
|
||||
./vanb the rug gary lent
|
||||
./vanb unix is better than os/2
|
||||
```sh
|
||||
./vanb the rug gary lent
|
||||
./vanb unix is better than os/2
|
||||
```
|
||||
|
||||
## Judges' remarks:
|
||||
|
||||
@@ -25,7 +29,7 @@ element on each line, followed by a line of ten dashes.
|
||||
|
||||
|
||||
|
||||
## Selected notes from the author:
|
||||
## Author's remarks:
|
||||
|
||||
The program has the following charming and possibly
|
||||
non-portable features:
|
||||
|
||||
+69
-48
@@ -1,23 +1,24 @@
|
||||
# Most algorithms in one program
|
||||
|
||||
Merlyn LeRoy (Brian Westley)
|
||||
Starfire Consulting
|
||||
1026 Blair Ave.
|
||||
St. Paul, MN
|
||||
55104
|
||||
USA
|
||||
|
||||
http://www.westley.org
|
||||
Merlyn LeRoy (Brian Westley)
|
||||
Starfire Consulting
|
||||
1026 Blair Ave.
|
||||
St. Paul, MN
|
||||
55104
|
||||
USA
|
||||
<http://www.westley.org>
|
||||
|
||||
## To build:
|
||||
|
||||
make all
|
||||
```sh
|
||||
make all
|
||||
```
|
||||
|
||||
|
||||
[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) was able to get
|
||||
this to partially work with clang; clang requires that the second, third and
|
||||
fourth args to main() be `char **`. Only `westley.c` and `ver0.c` (see below) will
|
||||
compile with clang. It's possible to get ver1.c to compile too but this causes
|
||||
compile with clang. It's possible to get `ver1.c` to compile too but this causes
|
||||
problems with generating the output of the remaining files so we have opted, at
|
||||
least for now, to not do that, as it does not have to output just source code.
|
||||
He notes that the original source code sometimes segfaults with `ver2` which
|
||||
@@ -28,31 +29,32 @@ Thank you Cody for your help!
|
||||
|
||||
## Try:
|
||||
|
||||
|
||||
./westley < westley.c > ver0.c
|
||||
./westley 1 < westley.c > ver1.c
|
||||
./westley 1 2 < westley.c > ver2.c
|
||||
./westley 1 2 3 < westley.c > ver3.c
|
||||
```sh
|
||||
./westley < westley.c > ver0.c
|
||||
./westley 1 < westley.c > ver1.c
|
||||
./westley 1 2 < westley.c > ver2.c
|
||||
./westley 1 2 3 < westley.c > ver3.c
|
||||
```
|
||||
|
||||
|
||||
Try compiling and running the 4 resulting programs. To compile try:
|
||||
|
||||
|
||||
make ver0
|
||||
make ver1
|
||||
make ver2
|
||||
make ver3
|
||||
```sh
|
||||
make ver0
|
||||
make ver1
|
||||
make ver2
|
||||
make ver3
|
||||
```
|
||||
|
||||
|
||||
|
||||
## Judges notes:
|
||||
## Judges' remarks:
|
||||
|
||||
|
||||
There is a secret way to get ONE of the versions to print out
|
||||
"Hello, world!\n". Can you find how to do it?
|
||||
|
||||
|
||||
## Selected notes from the author:
|
||||
## Author's remarks:
|
||||
|
||||
This is a filter. If it is run with no arguments, it copies
|
||||
stdin to stdout. With one argument, it ROT13's stdin to
|
||||
@@ -63,42 +65,44 @@ Also requires two's complement (I think).
|
||||
|
||||
The source code will run if ROT13'ed and/or reversed, using a
|
||||
different algorithm for each version (hereafter referred to as
|
||||
ver0 (original), ver1 (ROT13), ver2 (reversed), and ver3
|
||||
`ver0` (original), `ver1` (ROT13), `ver2` (reversed), and `ver3`
|
||||
(ROT13 and reversed)).
|
||||
|
||||
When compiling these versions, one needs to define 'trgpune'
|
||||
in the compile line (which the Makefile now has). Example:
|
||||
|
||||
cc -Dtrgpune=putchar ver3.c -o ver3
|
||||
```sh
|
||||
cc -Dtrgpune=putchar ver3.c -o ver3
|
||||
```
|
||||
|
||||
"trgpune" is the ROT13 of getchar(), so getchar() and putchar()
|
||||
`trgpune` is the ROT13 of `getchar()`, so `getchar()` and `putchar()`
|
||||
are exchanged in the ROT13 counterpart. It is easy to see that
|
||||
this is unavoidable. I must have a #define for a library
|
||||
this is unavoidable. I must have a `#define` for a library
|
||||
function; otherwise I would have an unidentified extern for the
|
||||
ROT13 version. If I then define this function, it won't link
|
||||
in the library version for the ORIGINAL code, since my
|
||||
definition will supersede the library function. Hence, the
|
||||
compiler option gives me putchar(), and allows me to use
|
||||
getchar(). I pass a dummy argument to getchar() to eliminate
|
||||
compiler option gives me `putchar()`, and allows me to use
|
||||
`getchar()`. I pass a dummy argument to `getchar()` to eliminate
|
||||
"variable number of args" from lint (unless it checks against
|
||||
the library). Otherwise, all versions lint reasonably (main
|
||||
returns random value & constant in conditional context [when I
|
||||
check for ROT13 version] is all it complains about).
|
||||
|
||||
ver0 and ver1 use a range check and a calculation to do ROT13,
|
||||
while ver2 and ver3 use table lookup. All versions contain
|
||||
main() and it's ROT13 fn, znva(). ver0/ver1 [ver2/ver3] are
|
||||
`ver0` and `ver1` use a range check and a calculation to do ROT13,
|
||||
while `ver2` and `ver3` use table lookup. All versions contain
|
||||
`main()` and it's ROT13 fn, `znva()`. `ver0`/`ver1` [`ver2`/`ver3`] are
|
||||
(of course) syntactically identical, since the syntax is in the
|
||||
non-alphabetic characters. However, since one program starts
|
||||
at main() while it's ROT13 counterpart starts at znva(), znva()
|
||||
calls main (znva() is also used for output).
|
||||
at `main()` while it's ROT13 counterpart starts at `znva()`, `znva()`
|
||||
calls main (`znva()` is also used for output).
|
||||
|
||||
All versions use recursion to work. If the program is NOT
|
||||
reversing it's output, it prints out the (possibly ROT13'd)
|
||||
character before recursing, otherwise it prints it out
|
||||
afterward (or doesn't recurse at all when EOF is reached).
|
||||
Since most of this code is identical, it is put into znva() and
|
||||
called with a first parameter of 0 as a flag (as "main()", it's
|
||||
Since most of this code is identical, it is put into `znva()` and
|
||||
called with a first parameter of 0 as a flag (as `main()`, it's
|
||||
first argument (argc) must be at least one).
|
||||
|
||||
I can't use any flow control. If I used if(), I would have a
|
||||
@@ -106,45 +110,62 @@ function vs() to define in the ROT13 version. But a function
|
||||
called vs() turns into a function called if() in the original,
|
||||
so it can't be done. Therefore, I do:
|
||||
|
||||
expr1 && expr2 && (expr3=etc);
|
||||
```c
|
||||
expr1 && expr2 && (expr3=etc);
|
||||
```
|
||||
|
||||
which is the same as:
|
||||
|
||||
if (expr1 && expr2) expr3=etc;
|
||||
```c
|
||||
if (expr1 && expr2) expr3=etc;
|
||||
```
|
||||
|
||||
A/UX on the Macintosh doesn't get this right; it evaluates ALL
|
||||
expressions if they aren't in an assignment or conditional
|
||||
statement. This might warrant a warning, since other compilers
|
||||
may do this. I found MANY compilers botched:
|
||||
|
||||
expr1 && (expr2,expr3);
|
||||
```c
|
||||
expr1 && (expr2,expr3);
|
||||
```
|
||||
|
||||
expr2 was OFTEN evaluated even if expr1 was false. I removed
|
||||
`expr2` was OFTEN evaluated even if `expr1` was false. I removed
|
||||
such statements to make it more portable.
|
||||
|
||||
The variable names are worth noting:
|
||||
|
||||
'irk' and 'vex' are ROT13 pairs and are synonyms.
|
||||
'Near' and 'Arne' are ROT13 pairs and are anagrams.
|
||||
'NOON' and 'ABBA' are ROT13 pairs and are palindromes.
|
||||
'tang' and 'gnat' are both ROT13 and palindrome pairs!
|
||||
--
|
||||
|
||||
'irk' and 'vex' are ROT13 pairs and are synonyms.
|
||||
|
||||
'Near' and 'Arne' are ROT13 pairs and are anagrams.
|
||||
|
||||
'NOON' and 'ABBA' are ROT13 pairs and are palindromes.
|
||||
|
||||
'tang' and 'gnat' are both ROT13 and palindrome pairs!
|
||||
|
||||
--
|
||||
|
||||
Normally (!), a reversible C program is done thus:
|
||||
|
||||
/**/ forward code /*/ edoc drawkcab /**/
|
||||
```c
|
||||
/**/ forward code /*/ edoc drawkcab /**/
|
||||
```
|
||||
|
||||
If your compiler nests comments, it will get this wrong.
|
||||
However, I have made some bits of the code palindromic,
|
||||
(or different, but reversible) so it is more like:
|
||||
|
||||
/**/forward/*//**/ palindromic /**//*/drawkcab/**/
|
||||
```c
|
||||
/**/forward/*//**/ palindromic /**//*/drawkcab/**/
|
||||
```
|
||||
|
||||
The code can therefore be interlaced. There are eight
|
||||
such palindromic bits. You can find them within the
|
||||
`/*//**/ /**//*/` pairs.
|
||||
|
||||
The body of the code of ver0 and ver1 is a large lumpy 'K' (for
|
||||
Kernighan); the code of ver2 and ver3 is a flat-topped and
|
||||
The body of the code of `ver0` and `ver1` is a large lumpy 'K' (for
|
||||
Kernighan); the code of `ver2` and `ver3` is a flat-topped and
|
||||
lumpier 'R' (for Ritchie). Judicious use of spaces and tabs
|
||||
helped here. It barely fits on an 80x24 screen. Squint. Note
|
||||
that the code must start with a blank line, or the reversed version
|
||||
|
||||
Reference in new issue
Block a user