improved indentation and whitespace for markdown code blocks
All code blocks in markdown have been intended by at least 4 spaces. We add `--tab-stop=8` to all `pandoc(1)` executions in order to set a better tab stop indentation, especially for tab intended code blocks. Changed `bin/pandoc-wrapper.sh` VERSION from "1.5.3 2024-03-26" to "1.6 2024-03-31". Fixed `1991/brnstnd/sorta.README.md` so that the sorta code is code blocks. Removed unneeded paragraph group in copyright in `inc/footer.default.html`. Fixed excess whitespace after list Author on entry `index.html` page. Changed `bin/output-index-author.sh` VERSION from "1.5.2 2024-03-26" to "1.6 2024-03-31". Performed `make www` to perform the above and test under macOS. TODO: Fix the problem of the initial line of code being extra intended. TODO: Fix excess whitespace around code that is inline.
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+13
-13
@@ -1,20 +1,20 @@
|
||||
## To build:
|
||||
|
||||
```sh
|
||||
make
|
||||
make
|
||||
```
|
||||
|
||||
|
||||
## To use:
|
||||
|
||||
```sh
|
||||
./prog "expression"
|
||||
./prog "expression"
|
||||
```
|
||||
|
||||
or:
|
||||
|
||||
```sh
|
||||
./prog
|
||||
./prog
|
||||
```
|
||||
|
||||
Type in expressions on standard input.
|
||||
@@ -23,13 +23,13 @@ Type in expressions on standard input.
|
||||
## Try:
|
||||
|
||||
```sh
|
||||
./try.sh
|
||||
./try.sh
|
||||
```
|
||||
|
||||
Notice how the script reads in from a file. If you type just:
|
||||
|
||||
```sh
|
||||
./prog
|
||||
./prog
|
||||
```
|
||||
|
||||
it will prompt you in the same way. Send ctrl-c to exit.
|
||||
@@ -38,7 +38,7 @@ it will prompt you in the same way. Send ctrl-c to exit.
|
||||
Finally, if you wish to read the man page:
|
||||
|
||||
```sh
|
||||
man ./calc.1
|
||||
man ./calc.1
|
||||
```
|
||||
|
||||
|
||||
@@ -52,7 +52,7 @@ author's remarks below.
|
||||
### Alternate build:
|
||||
|
||||
```sh
|
||||
make alt
|
||||
make alt
|
||||
```
|
||||
|
||||
|
||||
@@ -110,7 +110,7 @@ However, unlike any other calculator source code the author is aware of,
|
||||
this one contains no digits. At all. Anywhere. As in
|
||||
|
||||
```sh
|
||||
grep '[0-9]' prog.c || echo no digits!
|
||||
grep '[0-9]' prog.c || echo no digits!
|
||||
```
|
||||
|
||||
Nor are the digits simply obfuscated. There are no character constants. There
|
||||
@@ -192,8 +192,8 @@ long`. Changing the two `long long` typedefs to `long`, and compiling with `gcc
|
||||
shifts mod 32:
|
||||
|
||||
```
|
||||
1<<48
|
||||
65536 0x00010000
|
||||
1<<48
|
||||
65536 0x00010000
|
||||
```
|
||||
|
||||
gcc 4.2.1 without arguments compiles cleanly (e.g. `cc prog.c -o prog`).
|
||||
@@ -203,7 +203,7 @@ clang 3.6.0 lives up to its namesake, resounding on non-problems.
|
||||
To stifle these complaints:
|
||||
|
||||
```
|
||||
-Wno-return-type -Wno-parentheses -Wno-empty-body
|
||||
-Wno-return-type -Wno-parentheses -Wno-empty-body
|
||||
```
|
||||
|
||||
When invoked with `-ansi -pedantic`, there are two warnings, which can be ignored:
|
||||
@@ -223,8 +223,8 @@ If the program name begins with an `e`, it echoes `stdin` to `stdout`.
|
||||
This allows for a convenient test suite:
|
||||
|
||||
```sh
|
||||
ln -sf prog eprog
|
||||
PATH=. eprog < test.in | diff - test.out
|
||||
ln -sf prog eprog
|
||||
PATH=. eprog < test.in | diff - test.out
|
||||
```
|
||||
|
||||
### Spoilers:
|
||||
|
||||
+14
-15
@@ -132,8 +132,7 @@
|
||||
<h2 id="author"><a name="author"></a>Author:</h2>
|
||||
<ul>
|
||||
<li>Name: <a href="../../authors.html#Dave_Burton">Dave Burton</a><br>
|
||||
Location: <a href="../../location.html#US">US</a> - <em>United States of America</em> (<em>United States</em>)
|
||||
<br><br></li>
|
||||
Location: <a href="../../location.html#US">US</a> - <em>United States of America</em> (<em>United States</em>)</li>
|
||||
</ul>
|
||||
|
||||
<!-- END: next line ends content generated by: bin/output-index-author.sh -->
|
||||
@@ -142,25 +141,25 @@ Location: <a href="../../location.html#US">US</a> - <em>United States of America
|
||||
<!-- START: this line starts content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
|
||||
|
||||
<h2 id="to-build">To build:</h2>
|
||||
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="fu">make</span></span></code></pre></div>
|
||||
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a> <span class="fu">make</span></span></code></pre></div>
|
||||
<h2 id="to-use">To use:</h2>
|
||||
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="ex">./prog</span> <span class="st">"expression"</span></span></code></pre></div>
|
||||
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a> <span class="ex">./prog</span> <span class="st">"expression"</span></span></code></pre></div>
|
||||
<p>or:</p>
|
||||
<div class="sourceCode" id="cb3"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="ex">./prog</span></span></code></pre></div>
|
||||
<div class="sourceCode" id="cb3"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a> <span class="ex">./prog</span></span></code></pre></div>
|
||||
<p>Type in expressions on standard input.</p>
|
||||
<h2 id="try">Try:</h2>
|
||||
<div class="sourceCode" id="cb4"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="ex">./try.sh</span></span></code></pre></div>
|
||||
<div class="sourceCode" id="cb4"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a> <span class="ex">./try.sh</span></span></code></pre></div>
|
||||
<p>Notice how the script reads in from a file. If you type just:</p>
|
||||
<div class="sourceCode" id="cb5"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="ex">./prog</span></span></code></pre></div>
|
||||
<div class="sourceCode" id="cb5"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a> <span class="ex">./prog</span></span></code></pre></div>
|
||||
<p>it will prompt you in the same way. Send ctrl-c to exit.</p>
|
||||
<p>Finally, if you wish to read the man page:</p>
|
||||
<div class="sourceCode" id="cb6"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="fu">man</span> ./calc.1</span></code></pre></div>
|
||||
<div class="sourceCode" id="cb6"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a> <span class="fu">man</span> ./calc.1</span></code></pre></div>
|
||||
<h2 id="alternate-code">Alternate code:</h2>
|
||||
<p>An alternate version of this entry, <a href="prog.alt.c">prog.alt.c</a>, is provided.
|
||||
This alternate code is discussed in the “prog.c vs prog.alt.c” section of the
|
||||
author’s remarks below.</p>
|
||||
<h3 id="alternate-build">Alternate build:</h3>
|
||||
<div class="sourceCode" id="cb7"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="fu">make</span> alt</span></code></pre></div>
|
||||
<div class="sourceCode" id="cb7"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a> <span class="fu">make</span> alt</span></code></pre></div>
|
||||
<h3 id="alternate-use">Alternate use:</h3>
|
||||
<p>Use <code>prog.alt</code> as you would <code>prog</code> above.</p>
|
||||
<h2 id="judges-remarks">Judges’ remarks:</h2>
|
||||
@@ -190,7 +189,7 @@ corrected by adding <code>-fsigned-char</code> to the compile line.</p>
|
||||
<p>Yes, this is another calculator program.</p>
|
||||
<p>However, unlike any other calculator source code the author is aware of,
|
||||
this one contains no digits. At all. Anywhere. As in</p>
|
||||
<div class="sourceCode" id="cb8"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="fu">grep</span> <span class="st">'[0-9]'</span> prog.c <span class="kw">||</span> <span class="bu">echo</span> no digits!</span></code></pre></div>
|
||||
<div class="sourceCode" id="cb8"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a> <span class="fu">grep</span> <span class="st">'[0-9]'</span> prog.c <span class="kw">||</span> <span class="bu">echo</span> no digits!</span></code></pre></div>
|
||||
<p>Nor are the digits simply obfuscated. There are no character constants. There
|
||||
is only one single, short string, and it does not contain any obfuscated digits.
|
||||
And yet the output is in decimal and hexadecimal, and it accepts octal, decimal,
|
||||
@@ -246,13 +245,13 @@ they are to write.</p></li>
|
||||
<h3 id="compiler-warnings">Compiler warnings</h3>
|
||||
<p><code>calc</code> is C99 compliant, and is ANSI/C90 compliant except for wanting 64-bit <code>long long</code>. Changing the two <code>long long</code> typedefs to <code>long</code>, and compiling with <code>gcc -m32</code> yields a program that operates on 32-bit values, with wrap-around of
|
||||
shifts mod 32:</p>
|
||||
<pre><code>1<<48
|
||||
65536 0x00010000</code></pre>
|
||||
<pre><code> 1<<48
|
||||
65536 0x00010000</code></pre>
|
||||
<p>gcc 4.2.1 without arguments compiles cleanly (e.g. <code>cc prog.c -o prog</code>).
|
||||
This is my workaday compiler. gcc is also clean with <code>-ansi</code>, and <code>-std=c99</code>.</p>
|
||||
<p>clang 3.6.0 lives up to its namesake, resounding on non-problems.
|
||||
To stifle these complaints:</p>
|
||||
<pre><code>-Wno-return-type -Wno-parentheses -Wno-empty-body</code></pre>
|
||||
<pre><code> -Wno-return-type -Wno-parentheses -Wno-empty-body</code></pre>
|
||||
<p>When invoked with <code>-ansi -pedantic</code>, there are two warnings, which can be ignored:</p>
|
||||
<ul>
|
||||
<li><code>ISO C90 does not support 'long long'</code></li>
|
||||
@@ -266,8 +265,8 @@ To stifle these complaints:</p>
|
||||
<h3 id="test-suite">Test Suite:</h3>
|
||||
<p>If the program name begins with an <code>e</code>, it echoes <code>stdin</code> to <code>stdout</code>.
|
||||
This allows for a convenient test suite:</p>
|
||||
<div class="sourceCode" id="cb11"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="fu">ln</span> <span class="at">-sf</span> prog eprog</span>
|
||||
<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="va">PATH</span><span class="op">=</span>. <span class="ex">eprog</span> <span class="op"><</span> test.in <span class="kw">|</span> <span class="fu">diff</span> <span class="at">-</span> test.out</span></code></pre></div>
|
||||
<div class="sourceCode" id="cb11"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a> <span class="fu">ln</span> <span class="at">-sf</span> prog eprog</span>
|
||||
<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a> <span class="va">PATH</span><span class="op">=</span>. <span class="ex">eprog</span> <span class="op"><</span> test.in <span class="kw">|</span> <span class="fu">diff</span> <span class="at">-</span> test.out</span></code></pre></div>
|
||||
<h3 id="spoilers">Spoilers:</h3>
|
||||
<p>If you do not want to puzzle out how it works, see <a href="spoilers.html">spoilers.html</a>.</p>
|
||||
<!--
|
||||
|
||||
@@ -135,50 +135,50 @@ did the basic four operations, but as a programmer, I needed more, so those
|
||||
were added over time.</p>
|
||||
<p><code>calc</code> is a useful, functioning utility. The operators before the obfuscation
|
||||
dance began (this is called foreshadowing):</p>
|
||||
<pre><code>() forced precedence
|
||||
- ~ ? unary minus, compl, byteswap
|
||||
* / % & << >> mul, div, mod, bitand, shift: left, right
|
||||
+ - | ^ add, sub, bitor, xor
|
||||
NUM 0-9</code></pre>
|
||||
<pre><code> () forced precedence
|
||||
- ~ ? unary minus, compl, byteswap
|
||||
* / % & << >> mul, div, mod, bitand, shift: left, right
|
||||
+ - | ^ add, sub, bitor, xor
|
||||
NUM 0-9</code></pre>
|
||||
<p>This seemed like a reasonable candidate to experiment with obfuscation; perhaps
|
||||
it might yield good results.</p>
|
||||
<h2 id="principle-of-operation">Principle of operation</h2>
|
||||
<p>The algorithm was and is rather straightforward:</p>
|
||||
<pre><code>expr() {
|
||||
n = term()
|
||||
t = token()
|
||||
if (t == ADD) return n += expr()
|
||||
if (t == SUB) return n -= expr()
|
||||
if (t == BOR) return n |= expr()
|
||||
if (t == XOR) return n ^= expr()
|
||||
ungettoken(t)
|
||||
return n
|
||||
}
|
||||
term() {
|
||||
n = factor()
|
||||
t = token()
|
||||
if (t == MUL) return n *= term()
|
||||
if (t == DIV) return n /= term()
|
||||
if (t == AND) return n &= term()
|
||||
if (t == RSH) return n >> term()
|
||||
if (t == LSH) return n << term()
|
||||
ungettoken(t)
|
||||
return n
|
||||
}
|
||||
factor() {
|
||||
t = token()
|
||||
if (t == LPAREN) {
|
||||
n = expr()
|
||||
if token() == RPAREN
|
||||
return n
|
||||
error()
|
||||
}
|
||||
if (t == SUB) return -factor()
|
||||
if (t == CMP) return ~factor()
|
||||
if (t == QUE) return byteswap(factor())
|
||||
if (t == DIG) return strtol()
|
||||
error()
|
||||
}</code></pre>
|
||||
<pre><code> expr() {
|
||||
n = term()
|
||||
t = token()
|
||||
if (t == ADD) return n += expr()
|
||||
if (t == SUB) return n -= expr()
|
||||
if (t == BOR) return n |= expr()
|
||||
if (t == XOR) return n ^= expr()
|
||||
ungettoken(t)
|
||||
return n
|
||||
}
|
||||
term() {
|
||||
n = factor()
|
||||
t = token()
|
||||
if (t == MUL) return n *= term()
|
||||
if (t == DIV) return n /= term()
|
||||
if (t == AND) return n &= term()
|
||||
if (t == RSH) return n >> term()
|
||||
if (t == LSH) return n << term()
|
||||
ungettoken(t)
|
||||
return n
|
||||
}
|
||||
factor() {
|
||||
t = token()
|
||||
if (t == LPAREN) {
|
||||
n = expr()
|
||||
if token() == RPAREN
|
||||
return n
|
||||
error()
|
||||
}
|
||||
if (t == SUB) return -factor()
|
||||
if (t == CMP) return ~factor()
|
||||
if (t == QUE) return byteswap(factor())
|
||||
if (t == DIG) return strtol()
|
||||
error()
|
||||
}</code></pre>
|
||||
<h2 id="obfuscation-is-a-process">Obfuscation is a process</h2>
|
||||
<p>Within the above algorithm, there are many details unmentioned, all ripe for
|
||||
obfuscation:</p>
|
||||
|
||||
@@ -17,11 +17,11 @@ were added over time.
|
||||
dance began (this is called foreshadowing):
|
||||
|
||||
```
|
||||
() forced precedence
|
||||
- ~ ? unary minus, compl, byteswap
|
||||
* / % & << >> mul, div, mod, bitand, shift: left, right
|
||||
+ - | ^ add, sub, bitor, xor
|
||||
NUM 0-9
|
||||
() forced precedence
|
||||
- ~ ? unary minus, compl, byteswap
|
||||
* / % & << >> mul, div, mod, bitand, shift: left, right
|
||||
+ - | ^ add, sub, bitor, xor
|
||||
NUM 0-9
|
||||
```
|
||||
|
||||
This seemed like a reasonable candidate to experiment with obfuscation; perhaps
|
||||
@@ -33,41 +33,41 @@ it might yield good results.
|
||||
The algorithm was and is rather straightforward:
|
||||
|
||||
```
|
||||
expr() {
|
||||
n = term()
|
||||
t = token()
|
||||
if (t == ADD) return n += expr()
|
||||
if (t == SUB) return n -= expr()
|
||||
if (t == BOR) return n |= expr()
|
||||
if (t == XOR) return n ^= expr()
|
||||
ungettoken(t)
|
||||
return n
|
||||
}
|
||||
term() {
|
||||
n = factor()
|
||||
t = token()
|
||||
if (t == MUL) return n *= term()
|
||||
if (t == DIV) return n /= term()
|
||||
if (t == AND) return n &= term()
|
||||
if (t == RSH) return n >> term()
|
||||
if (t == LSH) return n << term()
|
||||
ungettoken(t)
|
||||
return n
|
||||
}
|
||||
factor() {
|
||||
t = token()
|
||||
if (t == LPAREN) {
|
||||
n = expr()
|
||||
if token() == RPAREN
|
||||
return n
|
||||
error()
|
||||
}
|
||||
if (t == SUB) return -factor()
|
||||
if (t == CMP) return ~factor()
|
||||
if (t == QUE) return byteswap(factor())
|
||||
if (t == DIG) return strtol()
|
||||
error()
|
||||
}
|
||||
expr() {
|
||||
n = term()
|
||||
t = token()
|
||||
if (t == ADD) return n += expr()
|
||||
if (t == SUB) return n -= expr()
|
||||
if (t == BOR) return n |= expr()
|
||||
if (t == XOR) return n ^= expr()
|
||||
ungettoken(t)
|
||||
return n
|
||||
}
|
||||
term() {
|
||||
n = factor()
|
||||
t = token()
|
||||
if (t == MUL) return n *= term()
|
||||
if (t == DIV) return n /= term()
|
||||
if (t == AND) return n &= term()
|
||||
if (t == RSH) return n >> term()
|
||||
if (t == LSH) return n << term()
|
||||
ungettoken(t)
|
||||
return n
|
||||
}
|
||||
factor() {
|
||||
t = token()
|
||||
if (t == LPAREN) {
|
||||
n = expr()
|
||||
if token() == RPAREN
|
||||
return n
|
||||
error()
|
||||
}
|
||||
if (t == SUB) return -factor()
|
||||
if (t == CMP) return ~factor()
|
||||
if (t == QUE) return byteswap(factor())
|
||||
if (t == DIG) return strtol()
|
||||
error()
|
||||
}
|
||||
```
|
||||
|
||||
## Obfuscation is a process
|
||||
|
||||
@@ -134,11 +134,11 @@ global pointer variable, and the integers from uninitialized global <code>int</c
|
||||
variables. If <code>x</code> is a global <code>int</code>, then <code>!x</code> is <code>1</code>, and the derivation
|
||||
proceeds from there, using some identities that are confusingly similar and
|
||||
interestingly combined (increasing obfuscation):</p>
|
||||
<pre><code>obc clr
|
||||
--- ---
|
||||
-~x x+1
|
||||
~-x x-1
|
||||
y-~x y+x+1</code></pre>
|
||||
<pre><code> obc clr
|
||||
--- ---
|
||||
-~x x+1
|
||||
~-x x-1
|
||||
y-~x y+x+1</code></pre>
|
||||
<p>The derived constants are a compromise between simple expressions, maximum utility,
|
||||
and minimum number of variables used.</p>
|
||||
<p>Command line arguments are copied into the upper half of the input buffer,
|
||||
|
||||
@@ -14,11 +14,11 @@ proceeds from there, using some identities that are confusingly similar and
|
||||
interestingly combined (increasing obfuscation):
|
||||
|
||||
```
|
||||
obc clr
|
||||
--- ---
|
||||
-~x x+1
|
||||
~-x x-1
|
||||
y-~x y+x+1
|
||||
obc clr
|
||||
--- ---
|
||||
-~x x+1
|
||||
~-x x-1
|
||||
y-~x y+x+1
|
||||
```
|
||||
|
||||
The derived constants are a compromise between simple expressions, maximum utility,
|
||||
|
||||
Reference in new issue
Block a user