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Merge pull request #1672 from xexyl/burton2015

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Add 2015/burton/try.sh + format/typo checks
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Landon Curt Noll authored and GitHub committed 2023-12-09 18:43:42 -08:00
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2015/burton/.gitignore
+1
View File
@@ -7,3 +7,4 @@ indent.o
prog
prog.alt
prog.orig
rule2
2015/burton/README.md
+43 -39
View File
@@ -23,42 +23,40 @@ Type in expressions on standard input.
### Try:
```sh
./prog '?0x3343<<2'
./try.sh
```
echo '?0x3343<<2' | ./prog
Notice how the script reads in from a file. If you type just:
```sh
./prog
```
Enter:
it will prompt you in the same way. Send ctrl-c to exit.
Finally, if you wish to read the man page:
```sh
a=0xfeedface
b=0xcafe
a << 16 + b
```
```sh
grep '[0-9]' prog.c
./prog < test.in
man ./calc.1
```
## Alternate code:
An alternate version of this entry, `prog.alt.c`, is provided.
An alternate version of this entry, [prog.alt.c](prog.alt.c), is provided.
This alternate code is discussed in the "prog.c vs prog.alt.c" section of the
author's remarks below.
To compile this alternate version:
### Alternate build:
```sh
make alt
```
### Alternate use:
Use `prog.alt` as you would `prog` above.
@@ -75,17 +73,19 @@ process.
## Author's remarks:
### calc - an integer expression calculator that outputs in both hex and decimal
All useful tools should include sufficient documentation.
See the included man page. ;-)
### Notes
This program is named calc. Onomatopoeia of sorts, in the visual realm. The
This program is named `calc`. Onomatopoeia of sorts, in the visual realm. The
formatting was easier: Form Follows Function (although [Hou][1] did this
better). It was tempting to call it iCalc, with i for integer (and it was
written on an iDevice), but sanity prevailed.
better). It was tempting to call it iCalc, with `i` for integer (and it was
written on an `iDevice`), but sanity prevailed.
Printed in 8 pt Courier, it makes aesthetically pleasing 8.5 x 11 wall art.
@@ -93,14 +93,15 @@ Printed in 8 pt Courier, it makes aesthetically pleasing 8.5 x 11 wall art.
### prog.c vs prog.alt.c
Dominik Muth observed a syntax error on `1+1`, `1-1`, `1|1`, and `1^1` when
using an ARM based computer, although `1*1` and others worked correctly. This
occurs because some platforms by default treat `char` as `unsigned char`. The
original code has this weakness, which can be corrected by adding
`-fsigned-char` to the compile line.
[Dominik Muth](/winners.html#Dominik_Muth) observed a syntax error on `1+1`,
`1-1`, `1|1`, and `1^1` when using an ARM based computer, although `1*1` and
others worked correctly. This occurs because some platforms by default treat
`char` as `unsigned char`. The original code has this weakness, which can be
corrected by adding `-fsigned-char` to the compile line.
The modified code is agnostic to `char` signedness.
### Why is this entry obfuscated/interesting?
Yes, this is another calculator program.
@@ -117,16 +118,17 @@ 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,
and hex input.
Flow control is by `for` and `return`. It is if-less, switch-less,
while-less, and hopeless. Literally, if not figuratively. ;-)
Flow control is by `for` and `return`. It is `if`-less, `switch`-less,
`while`-less, and hopeless. Literally, if not figuratively. ;-)
The code size is intentionally 2015, as stated by iocccsize -i, and can be
reformatted without changes (as in rule2.c) to exactly 4096 octets.
The code size is intentionally 2015, as stated by `iocccsize -i`, and can be
reformatted without changes (as in [rule2.c](rule2.c)) to exactly 4096 octets.
Finally, calc is interesting, if for no other reason than it is practically
Finally, `calc` is interesting, if for no other reason than it is practically
useful: Hex/decimal conversion, arithmetic, byte-swapping, bit-shifting, and
logical operations with memory, on the command line, or interactively.
### But the question is why is the entry obfuscated?
The code follows many industry best-practices:
@@ -161,8 +163,8 @@ and `long`; 10 if `#include` and `#define` are counted.
- The code helpfully declares `"syntax_error!"` right up front, filling the
reader with confidence.
- In spite of its inherent clarity, the code was presented to both *indent*(1)
and *clang-format*(1), after running it through the preprocessor, sustaining its
- In spite of its inherent clarity, the code was presented to both `indent(1)`
and `clang-format(1)`, after running it through the preprocessor, sustaining its
better qualities.
- That the code is obfuscated is spelled out two different ways in the source;
@@ -170,20 +172,21 @@ it helps to reformat the code to see the second spelling.
- The author is overly fond of the code that handles input. There is no memory
allocation, nor pre-allocation of arrays, so where does the memory come from?
The multi-base strtol() code is pretty tricky. No special attempt was made to
The multi-base `strtol(3)` code is pretty tricky. No special attempt was made to
replace operations with obscure mathematical relations, as the (lack of) beauty
is in the parsing -- ask not where is the modulus operation, but how does it
know when to mod -- okay, but where is add and subtract? And really, who
doesn't enjoy a setjmp() in the argument list?
doesn't enjoy a `setjmp(3)` in the argument list?
- Finally, documentation of the source code structure is helpfully provided in
rot13 format. But isn't it unsportsmanlike to rely upon it? However, even with
this helpful guide, things like reading input lines remain as tricky to read as
they are to write.
### Compiler warnings
Calc is C99 compliant, and is ANSI/C90 compliant except for wanting 64-bit `long
`calc` is C99 compliant, and is ANSI/C90 compliant except for wanting 64-bit `long
long`. Changing the two `long long` typedefs to `long`, and compiling with `gcc
-m32` yields a program that operates on 32-bit values, with wrap-around of
shifts mod 32:
@@ -193,8 +196,8 @@ shifts mod 32:
65536 0x00010000
```
gcc 4.2.1 without arguments compiles cleanly (e.g. cc prog.c -o prog).
This is my workaday compiler. gcc is also clean with -ansi, and -std=c99.
gcc 4.2.1 without arguments compiles cleanly (e.g. `cc prog.c -o prog`).
This is my workaday compiler. gcc is also clean with `-ansi`, and `-std=c99`.
clang 3.6.0 lives up to its namesake, resounding on non-problems.
To stifle these complaints:
@@ -203,19 +206,20 @@ To stifle these complaints:
-Wno-return-type -Wno-parentheses -Wno-empty-body
```
When invoked with -ansi -pedantic, there are two warnings, which can be ignored:
When invoked with `-ansi -pedantic`, there are two warnings, which can be ignored:
* `ISO C90 does not support 'long long'`
With -Wall -std=c99, both are quite noisy, and all can be ignored:
With `-Wall -std=c99`, both are quite noisy, and all can be ignored:
* `array subscript has type 'char' [-Wchar-subscripts]`
* `value computed is not used [-Wunused-value]`
* `operation on 'j' may be undefined [-Wsequence-point]`
### Test Suite:
If the program name begins with an "e", it echoes stdin to stdout.
If the program name begins with an `e`, it echoes `stdin` to `stdout`.
This allows for a convenient test suite:
```sh
2015/burton/road.to.obscurity → 2015/burton/road.to.obscurity.md
+116 -113
View File
@@ -1,5 +1,4 @@
Development of the obfuscated calculator.
--------------------------------------------------
# Development of the obfuscated calculator.
I wanted to enter the IOCCC....
@@ -8,83 +7,86 @@ is fierce, but not a closed door.
I needed an interesting program, that had a reasonable chance of being shrunk
within 4096 bytes, and lent itself to obfuscation. I had been revisiting
utilities I've written over the years. One useful program was calc, a simple
utilities I've written over the years. One useful program was `calc`, a simple
recursive descent signed integer expression parser I developed from first
principles as a demonstration of how computers work for my son. That program
did the basic four operations, but as a programmer, I needed more, so those
were added over time.
Calc is a useful, functioning utility. The operators before the obfuscation
dance began (this is called fore-shadowing):
`calc` is a useful, functioning utility. The operators before the obfuscation
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
it might yield good results.
Principle of operation
--------------------------------------------------
## Principle of operation
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()
```
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
--------------------------------------------------
## Obfuscation is a process
Within the above algorithm, there are many details unmentioned, all ripe for
obfuscation:
- input
- tokenization
- atoi input values
- sprintf results
- `atoi(3)` input values
- `sprintf(3)` results
- error recovery
- swapping bytes
- user interface (command line vs stdin)
- user interface (command line vs `stdin`)
Uncertain as to how this would progress, I started obfuscating/condensing
everything except the conversion operations, leaving those to sprintf() and
strtol(). The first version of the obfuscated code used an homage to 1984 anon
for I/O, and it featured a #define for else's and the types, to help minimize
everything except the conversion operations, leaving those to `sprintf(3)` and
`strtol(3)`. The first version of the obfuscated code used an homage to 1984 anon
for I/O, and it featured a `#define` for `else`s and the types, to help minimize
the repetition. And of course, most functions were renamed with one or two
letters, and most of the variables became single letter globals. Tokenization
was rather easy with a declared array, just initialized with unique values for
@@ -93,33 +95,33 @@ each.
This was when the obfuscation took a turn for the better (worse): it was easy
to hide the operations via a simple transformation. The code now dealt with
small integer values instead of direct ASCII representation of the operations.
And the strings where collapsed into a single combined error message and
And the strings were collapsed into a single combined error message and
operator tokenization table. This was relatively obscure.
Next, sprintf() was replaced with a custom formatter. This was rather simple,
Next, `sprintf(3)` was replaced with a custom formatter. This was rather simple,
but at least the formatting was not obvious. Formatting and printing were
split early. strtol() was replaced with custom logic, limited to 3 practical
split early. `strtol(3)` was replaced with custom logic, limited to 3 practical
bases: octal, decimal, and hex. The last result was remembered in a special
variable, dot.
By this time, I had a version which I considered obscure, and shared this early
version with a couple of colleagues for comments. I suggested I could improve
the obfuscation of a term() and factor(), and would like to have assignable
the obfuscation of a `term()` and `factor()`, and would like to have assignable
memories.
This code was pretty dense, but inspired by previous IOCCC entries, I thought I
might get rid of all the else's, which showed the structure of the parser
might get rid of all the `else`s, which showed the structure of the parser
rather clearly. Investing in the ternary operator, the code got quite a bit
more difficult to follow, used only for-loops, and I had to start taking notes
more difficult to follow, used only `for` loops, and I had to start taking notes
to follow it. This was a good sign! ;-)
I started testing the code. I wrote a test suite to ensure the changes I made
did not corrupt the processing (oh so easy to do with this obfuscated mess).
Why does -1>>32 yield -1? Oh, yeah: signed arithmetic. Enter Java's unsigned
shift: >>>. Better. But with more features, more to get wrong, and harder to
know which expression is causing the error. The easy solution: if the name
begins with 'e', echo the input. Now I can see the failing expression. Wait,
what is this test expression supposed to be testing?
Why does `-1>>32` yield `-1`? Oh, yeah: signed arithmetic. Enter Java's
`unsigned` shift: `>>>`. Better. But with more features, more to get wrong,
and harder to know which expression is causing the error. The easy solution: if
the name begins with `e`, echo the input. Now I can see the failing expression.
Wait, what is this test expression supposed to be testing?
Wouldn't it be nice to have comments?
@@ -130,8 +132,8 @@ statements on a single line (read: semicolon expression terminators). This
involved quite a bit of rework of the input code, but now allowed very
convenient user interaction.
Better Obscurity is a laborious process
--------------------------------------------------
## Better Obscurity is a laborious process
Satisfied with the functionality, but unsatisfied with the obscurity, I
pondered if I could get rid of all the constants? This had not been done
@@ -141,45 +143,46 @@ Obscurity now increased!
But wouldn't it be nice to have assignable memories?
Around this time, the formatted code no longer fit with the 2053 limit (due to
a lack of comprehension of the significance of the space-after-brace-and-semi
Around this time, the formatted code no longer fit with the 2053 limit (due to a
lack of comprehension of the significance of the space-after-brace-and-semi
rule, and a layout program that did not know how to do this). Frustrated, I
wrote another program to reformat this code into rule2.c, which was a single C
token per line. This solved the formatting problem, but intriguingly
wrote another program to reformat this code into [rule2.c](rule2.c), which was a
single C token per line. This solved the formatting problem, but intriguingly
introduced another. Now I was faced with the 4096 rule as well as the 2053
rule. But this was a challenge!
I wrote a de-obfuscator, and worked on both the unobfuscated version and the
master code. I worked on the template formatter to make this as automated as
possible, and worked to achieve both a perfectly presented picture AND the
single-line exactly-at-4096 rule2.c.
single-line exactly-at-4096 [rule2.c](rule2.c).
Finally, "perfection", with assignable memories! Where perfection is defined
as a nicely formatted picture at less than 2053, and exactly 4096
token-per-line rule2.c.
token-per-line [rule2.c](rule2.c).
Testing Testing Testing
--------------------------------------------------
Cross platform, it works on Mac OSX, fails on Linux. It works if #include
<stdlib.h>, but it dumps core without it (the only change!)?. 64bits without
proper declaration of ints in syscalls yields unpredictable results. 32bit
compilation showed problems with byte- swapping in using addition versus
bitwise-or. In 32bit land, x<<32 == x, so x<<32 + x>>32 does not yield the
desired result, but x<<32 | x>>32 does (with appropriate care and feeding).
## Testing Testing Testing
Cross platform, it works on Mac OSX, fails on Linux. It works if `#include
<stdlib.h>`, but it dumps core without it (the only change!)?. 64-bits without
proper declaration of `int`s in syscalls yields unpredictable results. 32-bit
compilation showed problems with byte-swapping in using addition versus
bitwise-or. In 32-bit land, `x<<32 == x`, so `x<<32 + x>>32` does not yield the
desired result, but `x<<32 | x>>32` does (with appropriate care and feeding).
And the different compilers on different hosts complained loudly and
differently, although all produced correct bits in spite of the noise.
Further, the program did not do UNIX pipelines well, due to the unbuffered
homage code (byte-at-a-time I/O), of which write() was also the source of the
portability problem. Replace write() with getchar()/putchar(), and it piped
well but lost some obscurity and no longer paid (direct) homage to history.
homage code (byte-at-a-time I/O), of which `write(2)` was also the source of the
portability problem. Replace `write(2)` with `getchar(3)`/`putchar(3)`, and it
piped well but lost some obscurity and no longer paid (direct) homage to
history.
Another problem: only one expression at a time was allowed on the command line,
no semis, no comments, and it turns out $2, $3, ... were not handled correctly.
no semis, no comments, and it turns out `$2`, `$3`, ... were not handled correctly.
Given the new I/O code, it was now possible to copy the command line arguments
into a buffer, and write a small routine to retrieve bytes from this buffer
like getchar(). Voila! Better obfuscation with much better functionality!
like `getchar(3)`. Voila! Better obfuscation with much better functionality!
But wouldn't it be nice to show what the current variables hold?
@@ -187,20 +190,20 @@ Bytes are now hard to find to keep exactly at 4096, and adding functionality to
obscured code is not easy. Restructuring the logic to gain the bytes
necessary, code to display the variables was added.
Test. Test. Test. Oh, noes! More bugs! Typing "1 + 2 5" yields 3, but no
syntax error. "g = 1" yields a syntax error, and "0xg" does not! ")" causes a
segfault! Why didn't I test these before I started obfuscating?! By this
point, everything I did to the code perturbed the 4096 bytes, all variables
were already a single character, and it was really difficult to follow the
logic in a debugger (single-stepping an expression did the entire line of code,
even if it involved multiple statements -- and it did, everywhere, even in the
Test. Test. Test. Oh, noes! More bugs! Typing "`1 + 2 5`" yields `3`, but
no syntax error. "`g = 1`" yields a syntax error, and "`0xg`" does not! "`)`"
causes a segfault! Why didn't I test these before I started obfuscating?! By
this point, everything I did to the code perturbed the 4096 bytes, all variables
were already a single character, and it was really difficult to follow the logic
in a debugger (single-stepping an expression did the entire line of code, even
if it involved multiple statements -- and it did, everywhere, even in the
unobfuscated version; think: a complex chain of ternary expressions is a single
statement). This involved careful examination of all the expressions within
the logic, trying to find a different way of getting the same result, but
typically within fewer bytes than before to allow for the added logic to fix
the bugs.
statement). This involved careful examination of all the expressions within the
logic, trying to find a different way of getting the same result, but typically
within fewer bytes than before to allow for the added logic to fix the bugs.
The bugs were fixed, the code re-formatted, and rule2.c was again 4096 bytes.
The bugs were fixed, the code re-formatted, and [rule2.c](rule2.c) was again
4096 bytes.
But wouldn't it be nice for unary plus to work?
@@ -211,22 +214,22 @@ this, bytes are scarce to come by.
But wouldn't it be nice for assignments to be silent?
Made them silent (easier said than done!). Why does "1 + 2 5" print a syntax
error, but "a = 1 + 2 5" does not? Rewrite(!) the assignment logic -- and this
requires more bytes!
Made them silent (easier said than done!). Why does "`1 + 2 5`" print a syntax
error, but "`a = 1 + 2 5`" does not? Rewrite(!) the assignment logic -- and
this requires more bytes!
Better Obscurity Through Simplification
--------------------------------------------------
Except there were not enough bytes to do this, unless #include <unistd.h> is
removed. But then sbrk() must be declared, eating into the savings. If only
## Better Obscurity Through Simplification
Except there were not enough bytes to do this, unless `#include <unistd.h>` is
removed. But then `sbrk()` must be declared, eating into the savings. If only
there were 512 bytes of memory already allocated that could be portably touched
for free....
Light bulb! Memory allocation was excised, and the code became more obscure.
It was working again! It formats beautifully, it compiled cleanly (with
apropos -Wno-guards), it remains obscure after cpp and clang-format, it
It was working again! It formats beautifully, it compiled cleanly (with apropos
`-Wno-guards`), it remains obscure after `cpp(1)` and `clang-format(1)`, it
measures within the limits and exactly at 4096 (this latter was really getting
challenging to maintain). No more bugs known, it is feature complete,
documentation written.
@@ -239,12 +242,12 @@ relatively tight. But changing around the stable initialization code -- by now
the largest piece of logic -- yielded the necessary bytes, and improved
obscurity by double duty encoding of the operations initialization.
The utility is now truly functional, and feature complete, and obscure.
Without src.doc (basic documentation of the code structure), and some commented
expanded logic stashed away, and the familiarity I have with the code having
written and revised it repeatedly, I would not even want to attempt to decipher
the logic. Many times in the debugging, I was thwarted by my own obfuscations,
and went down blind paths in trying to fix a bug or add functionality. Now I
think I have a good entry.
The utility is now truly functional, and feature complete, and obscure. Without
[src.doc.txt](src.doc.txt) (basic documentation of the code structure), and some
commented expanded logic stashed away, and the familiarity I have with the code
having written and revised it repeatedly, I would not even want to attempt to
decipher the logic. Many times in the debugging, I was thwarted by my own
obfuscations, and went down blind paths in trying to fix a bug or add
functionality. Now I think I have a good entry.
But wouldn't it be nice to import pre-set definitions from a file?
2015/burton/spoilers.md
+26 -22
View File
@@ -1,34 +1,38 @@
### Spoilers
Calc is a recursive-descent parser. It allocates from the stack deep enough
`calc` is a recursive-descent parser. It allocates from the stack deep enough
that all expressions are exhausted before the recursion stack depth reaches the
allocations. The memory map and source is documented in src.doc.txt. Tokens
are encoded using values 0-20, where 0 is an invalid token, 1 is minus, 2 is
space, 3 is plus, etc. The necessary constants are derived at the start of the program,
using the guarantee that globals are initialized to zero; so a correct null pointer
is obtained from an uninitialized global pointer variable, and the integers from
uninitialized global int variables. If x is a global int, then !x is 1, and the
derivation proceeds from there, using some identities that are confusingly similar
and interestingly combined (increasing obfuscation):
allocations. The memory map and source is documented in
[src.doc.txt](src.doc.txt). Tokens are encoded using values 0-20, where 0 is an
invalid token, 1 is minus, 2 is space, 3 is plus, etc. The necessary constants
are derived at the start of the program, using the guarantee that globals are
initialized to zero; so a correct NULL pointer is obtained from an uninitialized
global pointer variable, and the integers from uninitialized global `int`
variables. If `x` is a global `int`, then `!x` is `1`, and the derivation
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,
and minimum number of variables used.
Command line arguments are copied into the upper half of the input buffer,
separated by a space. This allows the code to have a single input parser by using
a pointer-to-func to either getchar() if live, or a getchar() simulator.
a pointer-to-func to either `getchar(3)` if live, or a `getchar(3)` simulator.
A small amount of obfuscation comes from void functions declared int, but missing return.
This is necessary to allow these functions in ternary ?: expressions and paired with && and ||;
but the requisite returns would add symbol count at no benefit to obscurity or functionality.
Function decomposition was mostly chosen to avoid curly braces:
if a for-loop required multiple statements, the body became a new function.
Last, but not least: sharing state via global variables is an ancient and honored
form of obfuscation, and remarkably effective.
A small amount of obfuscation comes from `void` functions declared `int`, but
missing `return`. This is necessary to allow these functions in ternary `?:`
expressions and paired with `&&` and `||`; but the requisite returns would add
symbol count at no benefit to obscurity or functionality. Function
decomposition was mostly chosen to avoid curly braces: if a `for`-loop required
multiple statements, the body became a new function. Last, but not least:
sharing state via global variables is an ancient and honored form of
obfuscation, and remarkably effective.
2015/burton/src.doc.txt
+5 -5
View File
@@ -20,7 +20,7 @@ td J jmp_buf
c *K pointer to cmd line args
td L char
v M(u64) detect errors, save answer in dot, format result in decimal and hex
c *N freebie null pointer
c *N freebie NULL pointer
td O unsigned char
td P void
td Q int
@@ -37,12 +37,12 @@ i64 a derived: 32
i64 b derived: 1
i64 _b(i64) term: << >> >>>
i64 c derived: 10
i64 _c(c*) convert binary global j to ascii decimal
i64 _c(c*) convert binary global j to ASCII decimal
i64 d freebie: 0
v _d(i64) accumulate converted ascii bytes into j in base passed in
v _d(i64) accumulate converted ASCII bytes into j in base passed in
i64 e derived: 256
i64 f derived: 2
i64 _f() convert from ascii to binary: selects convert base (10,8,16), result in j
i64 _f() convert from ASCII to binary: selects convert base (10,8,16), result in j
u64 g(u16) byte swap 16-bits
u64 h(u32) byte swap 32-bits
i64 i(u64) select size and byte swap minimal bytes
@@ -54,7 +54,7 @@ jb l for parser error recovery
c m() scans input for token, ignores whitespace
c n() get next input character
i64 *o registers
u32 p(c*) writes to stdout until null, newline appended intelligently
u32 p(c*) writes to stdout until NUL, newline appended intelligently
v q(**) init
i64 r(c) writes c to stdout
i64 s derived: 8
2015/burton/try.sh
Executable
+47
View File
@@ -0,0 +1,47 @@
#!/usr/bin/env bash
#
# try.sh - demonstrate IOCCC winner 2015/burton
#
# make sure CC is set so that when we do make CC="$CC" it isn't empty. Doing it
# this way allows us to have the user specify a different compiler in an easy
# way.
if [[ -z "$CC" ]]; then
CC="cc"
fi
make CC="$CC" all >/dev/null || exit 1
# clear screen after compilation so that only the entry is shown
clear
echo "$ ./prog '?0x3343<<2'" 1>&2
./prog '?0x3343<<2'
echo "$ echo '?0x3343<<2' | ./prog" 1>&2
echo '?0x3343<<2' | ./prog
echo "$ grep '[0-9]' prog.c" 1>&2
read -r -n 1 -p "Press any key to continue (notice how there are no digits!): "
echo 1>&2
grep -c '[0-9]' prog.c
read -r -n 1 -p "Press any key to run: ./prog < test.in: "
echo 1>&2
./prog < test.in
echo 1>&2
read -r -n 1 -p "Press any key to show try.this.txt: "
echo 1>&2
cat try.this.txt
echo 1>&2
read -r -n 1 -p "Press any key to run: ./prog < try.this.txt: "
echo 1>&2
./prog < try.this.txt
read -r -n 1 -p "Press any key to show the hex value of 42: "
echo 1>&2
echo "$ ./prog 42" 1>&2
./prog 42
2015/burton/try.this.txt
+6
View File
@@ -0,0 +1,6 @@
a=0xfeedface
b=0xcafe
a << 16 + b
a=0xdeadbeef
b=0xcafe
a << 16 + b
thanks-for-help.md
+8
View File
@@ -3796,6 +3796,14 @@ output.
# <a name="2015"></a>2015
## <a name="2015_burton"></a>[2015/endoh3](/2015/burton/prog.c) ([README.md](/2015/burton/README.md]))
[Cody](#cody) added the [try.sh](/2015/burton/try.sh) script. This involved
adding a text file, [try.this.txt](/2015/burton/try.this.txt).
## <a name="2015_dogon"></a>[2015/endoh3](/2015/dogon/prog.c) ([README.md](/2015/dogon/README.md]))
[Cody](#cody) improved the Makefile so that one can easily change the dimensions