Format and typo fix 2000/dlowe/README.md
This commit is contained in:
Cody Boone Ferguson committed
1 parent
73d0c06440
commit
64f0c5c84f
1 file changed
+59
-54
+59
-54
@@ -1,11 +1,9 @@
|
||||
# Worst Abuse of the Rules
|
||||
|
||||
David Lowe
|
||||
1224 11th Avenue
|
||||
San Francisco, California, 94122
|
||||
USA
|
||||
|
||||
http://pootpoot.com/~dlowe/
|
||||
David Lowe
|
||||
1224 11th Avenue
|
||||
San Francisco, California, 94122
|
||||
USA
|
||||
|
||||
## To build:
|
||||
|
||||
@@ -22,6 +20,7 @@ perl -MConfig -e 'print "$Config{archlibexp}/CORE\n"'
|
||||
[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed this to compile
|
||||
with more recent perl versions; the symbol now `PL_na` was once `na`. He notes
|
||||
that this entry crashes under macOS but it works under linux after this change.
|
||||
Thank you Cody for your assistance!
|
||||
|
||||
|
||||
## To run:
|
||||
@@ -41,8 +40,8 @@ echo "13 14 15 16 17 + - * / p" | ./dlowe
|
||||
When this entry was submitted the rules of the IOCCC did not prohibit
|
||||
the use of embedded language interpreters. The judges considered
|
||||
disqualifying this entry because of the use of perl, but on the other
|
||||
hand it qualifies as the Worst Abuse of the Rules. As a previous winner
|
||||
* David Lowe continues to inflict the highest quality "poot" on the
|
||||
hand it qualifies as the Worst Abuse of the Rules. As a previous winner\*
|
||||
David Lowe continues to inflict the highest quality "poot" on the
|
||||
Judges.
|
||||
|
||||
The program also contains an undocumented command for Chad and Chongo.
|
||||
@@ -53,30 +52,33 @@ of the submitters hidden until all the prize winners have been selected.
|
||||
|
||||
## Author's remarks:
|
||||
|
||||
### Usage:
|
||||
### Usage
|
||||
|
||||
./dlowe [file ...]
|
||||
|
||||
### Synopsis:
|
||||
### Synopsis
|
||||
|
||||
This is a reverse polish calculator, loosely based on the dc(1) unix
|
||||
This is a reverse polish calculator, loosely based on the `dc(1)` unix
|
||||
calculator.
|
||||
|
||||
# Syntax:
|
||||
# Syntax
|
||||
|
||||
This program understands the following dc(1) commands:
|
||||
This program understands the following `dc(1)` commands:
|
||||
|
||||
p prints the top stack value without altering the stack.
|
||||
P prints the top stack value, removing it from the stack, and
|
||||
doesn't print a trailing newline.
|
||||
f prints the contents of the stack, one number per line,
|
||||
without modifying it.
|
||||
c clears the stack.
|
||||
d pushes a copy of the top stack value onto the stack.
|
||||
r reverses the order of the top two stack values.
|
||||
```
|
||||
p prints the top stack value without altering the stack.
|
||||
P prints the top stack value, removing it from the stack, and
|
||||
doesn't print a trailing newline.
|
||||
f prints the contents of the stack, one number per line,
|
||||
without modifying it.
|
||||
c clears the stack.
|
||||
d pushes a copy of the top stack value onto the stack.
|
||||
r reverses the order of the top two stack values.
|
||||
```
|
||||
|
||||
And the following arithmetic operators are supported:
|
||||
|
||||
```
|
||||
+ Pops 2 values and pushes their sum.
|
||||
- Pops 2 values and pushes the result of subtracting the first
|
||||
from the second.
|
||||
@@ -87,14 +89,15 @@ And the following arithmetic operators are supported:
|
||||
to the power of the first.
|
||||
% Pops 2 values and pushes the remainder of the division that
|
||||
/ would do.
|
||||
```
|
||||
|
||||
The precision and range are double, like it or not, except that the
|
||||
modulus operator actually returns (p1 - (p2 * (p1 / p2))), but with
|
||||
modulus operator actually returns `(p1 - (p2 * (p1 / p2)))`, but with
|
||||
the innermost division calculated at integer precision. This is
|
||||
usually what you expect (e.g. echo "12 8 % p" | ./dlowe == 4)
|
||||
usually what you expect (e.g. `echo "12 8 % p" | ./dlowe == 4`)
|
||||
|
||||
Commands are read from stdin or from a list of files named on
|
||||
the command line. Unlike dc(1), multiple commands on the same line
|
||||
the command line. Unlike `dc(1)`, multiple commands on the same line
|
||||
must be space separated. Commands are only executed when a newline
|
||||
or EOF is encountered.
|
||||
|
||||
@@ -153,9 +156,9 @@ error reporting.
|
||||
|
||||
Unfortunately, Perl is an evolving beast - that includes the
|
||||
embedding API and the XS API. The code was developed under
|
||||
Perl 5.005_03, successfully tested against Perl 5.6.0, Perl 5.005_02
|
||||
and Perl 5.004_04, and according to the version delta documentation,
|
||||
should work as-is with Perl 5.002 and later (which has been around
|
||||
`Perl 5.005_03`, successfully tested against `Perl 5.6.0`, `Perl 5.005_02`
|
||||
and `Perl 5.004_04`, and according to the version delta documentation,
|
||||
should work as-is with Perl 5.002` and later (which has been around
|
||||
since February 1996). To clarify - it's not the Perl code itself
|
||||
that may be non-portable, it's the C code for embedding Perl and for
|
||||
calling C from Perl.
|
||||
@@ -169,7 +172,7 @@ by slight misconfigurations of Perl on your system.
|
||||
|
||||
Some compilers also complain that "third argument of `main' is
|
||||
deprecated" or something to that effect. But in Perl prior to
|
||||
5.6.0, the header file "proto.h" actually had a prototype for main,
|
||||
`5.6.0`, the header file "proto.h" actually had a prototype for main,
|
||||
so applications which embed Perl must use the three argument form
|
||||
of main.
|
||||
|
||||
@@ -182,52 +185,52 @@ say, camels and humps.
|
||||
|
||||
### Obfuscated?
|
||||
|
||||
. Reverse polish notation is pretty strange, in and of itself.
|
||||
- Reverse polish notation is pretty strange, in and of itself.
|
||||
|
||||
. The layout of the program is three roughly symmetrical "stacks"
|
||||
- The layout of the program is three roughly symmetrical "stacks"
|
||||
of code. This layout is quite sensitive in places - my C indenter
|
||||
actually breaks the code by inserting spaces in certain places.
|
||||
|
||||
. Anyone who has ever programmed in Perl can attest to the fact that
|
||||
- Anyone who has ever programmed in Perl can attest to the fact that
|
||||
it is particularly well-suited to obfuscation; thus, the Perl is
|
||||
obfuscated. (Here's my favorite legal Perl from this program:
|
||||
'_:$_=<>;' - but '$SS[$#SS]-=$SS[$#SS-1]' isn't bad, either).
|
||||
`_:$_=<>;` - but `$SS[$#SS]-=$SS[$#SS-1]` isn't bad, either).
|
||||
|
||||
. I've eschewed traditional branch and loop structures such as
|
||||
'if' and 'for', in favor of their oft-neglected cousins, 'goto'
|
||||
and '?:', in both the Perl and C code.
|
||||
- I've eschewed traditional branch and loop structures such as
|
||||
`if` and `for`, in favor of their oft-neglected cousins, `goto`
|
||||
and `?:`, in both the Perl and C code.
|
||||
|
||||
. I've used some highly magical Perl incantations, such as symbolic
|
||||
references, the 'goto &NAME' syntax, AUTOLOAD for exception handling,
|
||||
and abuse of the default scalar ($_).
|
||||
- I've used some highly magical Perl incantations, such as symbolic
|
||||
references, the `goto &NAME` syntax, `AUTOLOAD` for exception handling,
|
||||
and abuse of the default scalar (`$_`).
|
||||
|
||||
. I've also deliberately used Perl syntax that is very much unlike
|
||||
C syntax: the &NAME rather than NAME() function calling syntax,
|
||||
leaving off parentheses wherever possible, using print() instead
|
||||
of printf(), and using the English style logic operators 'and' and
|
||||
'or' rather than '&&' and '||', for example.
|
||||
- I've also deliberately used Perl syntax that is very much unlike
|
||||
C syntax: the `&NAME` rather than `NAME()` function calling syntax,
|
||||
leaving off parentheses wherever possible, using `print()` instead
|
||||
of `printf()`, and using the English style logic operators `and` and
|
||||
`or` rather than `&&` and `||`, for example.
|
||||
|
||||
. The fact that all the Perl code is in double-quotes doesn't lend
|
||||
- The fact that all the Perl code is in double-quotes doesn't lend
|
||||
any readability to the regular expressions and quoted strings
|
||||
therein.
|
||||
|
||||
. The points and ways in which C and Perl connect are *really*
|
||||
- The points and ways in which C and Perl connect are *really*
|
||||
obscure. They're also incredibly poorly documented, as they're
|
||||
primarily used in machine-generated code. However, there's a
|
||||
wealth of example code on CPAN (www.cpan.org).
|
||||
wealth of example code on [CPAN (www.cpan.org)](https://www.cpan.org).
|
||||
|
||||
. The Perl API functions are almost all macros, so you will probably
|
||||
- The Perl API functions are almost all macros, so you will probably
|
||||
find that preprocessor expansion will only make things worse. They
|
||||
also have helpful, verbose names like SvNV, SvIV, and newSVpv. I
|
||||
also have helpful, verbose names like `SvNV`, `SvIV`, and `newSVpv`. I
|
||||
couldn't have done better myself!
|
||||
|
||||
. Figuring out how the mathematical C functions get called is a bit
|
||||
- Figuring out how the mathematical C functions get called is a bit
|
||||
tricky. Note the lack of explicit switching based on command
|
||||
input.
|
||||
|
||||
. Because of the "interesting" way that commands are interpreted,
|
||||
- Because of the "interesting" way that commands are interpreted,
|
||||
all of the commands have synonyms. For example, if you find it
|
||||
easier to remember, '=' is synonymous with 'd'. This is makes it
|
||||
easier to remember, `=` is synonymous with `d`. This also makes it
|
||||
possible to write (even more) obfuscated reverse polish commands
|
||||
(I figure this explanation moves the synonyms from 'bug' to
|
||||
'feature'!)
|
||||
@@ -235,13 +238,15 @@ possible to write (even more) obfuscated reverse polish commands
|
||||
. The first IOCCC entry with an "easter egg"?...
|
||||
|
||||
|
||||
Aside: on unobfuscated Perl
|
||||
### Aside: on unobfuscated Perl
|
||||
|
||||
My original intent was to write obfuscated C and crystal-clear Perl,
|
||||
to highlight my bending of the rules. Unfortunately, Perl really
|
||||
doesn't lend itself to crystal-clear code...
|
||||
|
||||
|
||||
Bending the rules?
|
||||
### Bending the rules?
|
||||
|
||||
Well, the rules never state that you can't embed another programming
|
||||
language, but on the other hand, knowing Perl probably isn't high on
|
||||
the list of qualifications for judges... Oh dear, I guess your C
|
||||
@@ -251,7 +256,7 @@ If you don't change the rules, it'll be embedded Ada next year!
|
||||
|
||||
### AutoDefend
|
||||
|
||||
A. Isn't this the obfuscated C contest? What's this Perl $#_&&$_?
|
||||
A. Isn't this the obfuscated C contest? What's this Perl `$#_&&$_`?
|
||||
|
||||
D. Hey, this program *is* 100% C, and does not exec an external Perl
|
||||
interpreter. It simply links against the Perl language library.
|
||||
|
||||
Reference in new issue
Block a user