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Merge pull request #1673 from xexyl/schweikhardt15

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Add 2015/schweikhardt/try.sh + format/typo checks
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Landon Curt Noll authored and GitHub committed 2023-12-09 18:44:08 -08:00
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2015/schweikhardt/README.md
+128 -84
View File
@@ -5,6 +5,17 @@ make
```
### Bugs and (Mis)features:
The current status of this entry is:
```
STATUS: INABIAF - please **DO NOT** fix
```
For more detailed information see [2015 schweikhardt in bugs.md](/bugs.md#2015-schweikhardt).
## To use:
```sh
@@ -17,7 +28,7 @@ where n is a base 16 number of any size.
### Try:
```sh
./prog 19
./try.sh
```
@@ -35,7 +46,8 @@ The code compiles without warnings on the systems that we tested!
Even more, the code was 100% clean when we ran it against various
static source checkers.
This tool references a problem that David I. Bell once described
This tool references a problem that [David I.
Bell](http://members.tip.net.au/~dbell/) once described
as having one of the largest "yummo quotients" in number theory:
```
@@ -44,11 +56,13 @@ yummo quotient = -----------------------------------
complexity of the problem statement
```
Erdős privately told one of the IOCCC judges:
[Erdős](https://en.wikipedia.org/wiki/Paul_Erdős) privately told one of the IOCCC judges:
> Solving the [Generalized Riemann
hypothesis](https://en.wikipedia.org/wiki/Generalized_Riemann_hypothesis#Extended_Riemann_hypothesis_.28ERH.29)
would be a good warm-up exercise for someone to get ready to begin to work on
the [Collatz conjecture](https://en.wikipedia.org/wiki/Collatz_conjecture).
"Solving the [Generalized Riemann hypothesis](https://en.wikipedia.org/wiki/Generalized_Riemann_hypothesis#Extended_Riemann_hypothesis_.28ERH.29)
would be a good warmup exercise for someone to get ready
to begin to work on the [Collatz conjecture](https://en.wikipedia.org/wiki/Collatz_conjecture)."
You may explore this famous conjecture using this entry:
@@ -64,6 +78,8 @@ You may explore this famous conjecture using this entry:
./prog 302ab3d052fb87c06228d249581be0e4
```
NOTE: [try.sh](try.sh) runs these for you, filtered through `less(1)`.
When you first look at the source, the code looks fairly straightforward.
But look again. Like the Collatz conjecture, simplicity is deceptive!
Oh, and the variable names? They are not simple single letter variables,
@@ -78,6 +94,7 @@ code is magic number free.
## Author's remarks:
### The TL;DR version
This is the cleanest program ever submitted. If for some input it enters
@@ -90,19 +107,24 @@ The program illustrates the bloat caused by adherence to too many rules,
each of which may sound sane in isolation, but in their entirety lead to
an obfuscated, hard to read and understand monster.
### What this program does.
The program tests whether a given natural number satisfies the
[Collatz Conjecture](https://en.wikipedia.org/wiki/Collatz_conjecture):
Take any natural number `n`. If `n` is even, divide it by `2` to get `n/2`.
If `n` is odd, multiply it by 3 and add 1 to obtain `3n + 1`.
Repeat the process indefinitely.
Take any natural number `n`. If `n` is even, divide it by `2` to get `n/2`. If
`n` is odd, multiply it by `3` and add `1` to obtain `3n + 1`. Repeat the
process indefinitely.
The conjecture is that no matter what number you start with,
you eventually reach 1.
you eventually reach `1`.
Paul Erdős said about the Collatz conjecture:
"Mathematics may not be ready for such problems."
> "Mathematics may not be ready for such problems."
He also offered $500 for its solution.
For example, the sequence of numbers for `n` = 6 is
@@ -113,14 +135,19 @@ Continuing past one leads to the *cycle* 1, 4, 2, 1, 4, 2, 1, ...
Interesting factoid: if you allow *negative* start values, there are
a few more cycles, each of different length:
> −1, −2, −1
>
> −5, −14, −7, −20, −10, −5
>
> −17, −50, −25, −74, −37, −110, −55, −164, −82, −41, −122, −61, −182, −91, −272, −136, −68, −34, −17
```
−1, −2, −1
−5, −14, −7, −20, −10, −5
−17, −50, −25, −74, −37, −110, −55, −164,
−82, −41, −122, −61, −182, −91, −272, −136,
−68, −34, −17
```
The program computes the sequence for a given positive natural number
and stops at 1. The number `n` is specified in hexadecimal (without 0x
and stops at `1`. The number `n` is specified in hexadecimal (without `0x`
prefix) as the first argument. The program prints the given number in
zero-padded hex and each iteration along with a line count in decimal.
The example above looks like this (compiled with 64 bit word size):
@@ -139,7 +166,7 @@ $ ./prog 6
```
The size of `n` is only limited by the argument size limit of your
shell/OS (the program implements arbitrary size bignums).
shell/OS (the program implements arbitrary size `bignum`s).
To query this on your POSIX system, run
```sh
@@ -172,7 +199,7 @@ For a given `n` the program behavior is one of the following 3:
mathematicians have tested all `n < 4FFDD776055A0000` (~10<sup>18</sup>) so
don't try anything less than that.
2. The chosen `n` leads to a sequence with ever bigger numbers, so that
eventually the bignum cannot be stored in memory. If this happens, the program
eventually the `bignum` cannot be stored in memory. If this happens, the program
outputs `laugh` (more likely) or `throw up` (less likely) and stops. You *might*
have found a number for which the sequence *diverges*. If confirmed, this
disproves the conjecture.
@@ -180,6 +207,7 @@ disproves the conjecture.
the same sequence over and over). You have disproved the conjecture and should
certainly submit a paper to the nearest mathematical journal.
### Design objectives
I gave myself the following objectives. Like in real world programming,
@@ -188,11 +216,11 @@ continuum, where trade-offs have to be made.
1. No arbitrary limits on the input number. 64 bits might be enough
for everybody, but is not enough for exploring new Collatz-territory.
Thus bignums are required.
Thus `bignums` are required.
2. Ultra-portable. Must run on C89 systems and self-adapt to C99 and C11
features like exact width types.
3. Super-efficient. Must be able to run with the widest type as the
base of the bignums. Make the user select the widest type supported
base of the `bignums`. Make the user select the widest type supported
by the implementation and then crunch away. If a non-standard
128bit type is available, it should be usable.
4. Pentagon level lint cleanliness and MISRA compliance.
@@ -200,6 +228,7 @@ by the implementation and then crunch away. If a non-standard
programmers. The epitome of best practice demonstration for all
future textbooks on C.
### Program Obfuscation
In the following I address all the *tests* as specified by your honors in the
@@ -214,6 +243,7 @@ In the following I address all the *tests* as specified by your honors in the
* compile it (with flags to enable all warnings)
* execute it
### Look at the original source
Using one letter identifiers is quite old. I decided to use TLI (three
@@ -250,44 +280,48 @@ acid](https://en.wikipedia.org/wiki/Proteinogenic_amino_acid)):
glx Glutamic acid or Glutamine
xle Leucine or Isoleucine
unk Unknown
``
```
My own research results complete this list (not yet in Wikipedia due to
the rule "[No original
research](https://en.wikipedia.org/wiki/Wikipedia:No_original_research)"):
```
and Androgynine
xor Xenoricine
not Notanamine
tla Triletramine
and Androgynine
xor Xenoricine
not Notanamine
tla Triletramine
```
Interestingly, the TLI are the perfect mnemonics for C language source.
For example, `met` is "Main's Exit Type" (`int`), `ala` is "A Large
Algebraic" (bignum), `ile` an "Incremented Local Entity" (index
counter), `gly` means "Grow Larger memorY", `gln` is "Grown Larger Now"
(after realloc), `not` is a "Not Overflowing Type" (recursive!), `unk`
is the "UNit (Known as 1)", `trp` is the "Tabula Rasa Product" (zero),
`phe` is "Print HEx" and so on.
For example, `met` is "`main()'s Exit Type`" (`int`), `ala` is "`A Large
Algebraic`" (`bignum`), `ile` an "`Incremented Local Entity`" (index
counter), `gly` means "`Grow Larger memorY`", `gln` is "`Grown Larger Now`"
(after `realloc(3)`), `not` is a "`Not Overflowing Type`" (recursive!), `unk`
is the "`UNit (Known as 1)`", `trp` is the "`Tabula Rasa Product`" (zero),
`phe` is "`Print HEx`" and so on.
### Convert ANSI trigraphs to ASCII
Huh??!
### C pre-process the source ignoring '#include' lines
### C pre-process the source ignoring `#include` lines
Wow, an identity operation (except for the `<stdint.h>` and `EOF + __STDC__`
trivialities). Did you gain any insight through this?
### C pre-process the source ignoring '#define' and '#include' lines
`#define`? Which `#define` directives? How many 4K source files do you
see that neither use a single `#define` directive *nor* abuse the build
see that don't use a single `#define` directive *or* abuse the build
file? Even though the "no `#define`" rule I submitted myself to made it
hard, I could use `__LINE__` and stdio macros `EOF`, `L_tmpnam`,
hard, I could use `__LINE__` and `stdio.h` macros `EOF`, `L_tmpnam`,
`BUFSIZ`, `FILENAME_MAX`, `TMP_MAX` to obfuscate at least something.
### Run it through a C beautifier
Another identity operation. I've done it for you already. Use this
@@ -314,15 +348,15 @@ $ cat .indent.pro
-Tala
```
It looks like a perfect program should:
It looks like a perfect program should have:
* two and a half `#includes` of unsuspicious standard headers
* two and a half `#include`s of non-suspicious standard headers
* followed by self protection against goofy implementations
* followed by a handful of `typedef`s
* and a pair of file scope objects by necessity
* prototypes! With parameter names! `static` for internal linkage even! This __must__ be a first in IOCCC history.
* function definitions, `main` last
* everything is fully const-poisoned: automatics, statics, arguments, even `main`
* everything is fully `const`-poisoned: automatics, statics, arguments, even `main`
* everything is fully curly braced, even single statements
* plenty of meaningful TLC (Three Letter Comments)
@@ -332,10 +366,11 @@ engineers). How many programs have *that* property? The check for
`__STDC_VERSION__` was a bit tough to arrive at, since 199901L has too
many bits set. But I realized that I only needed a number larger than
199409 and less than 199901. 199680 has only 4 bits set and writing it
as (256 + 128 + 4 + 2) * 512 minimizes the character count. That's what
as `(256 + 128 + 4 + 2) * 512` minimizes the character count. That's what
judges get when they don't like programs that are longer than they need
to be.
### Examine the algorithm
Spoilers ahead. Duh!
@@ -361,15 +396,16 @@ if (non-NULL and nonempty argv[1]) {
}
```
Bignums are represented as the two member structs
`Bignum`s are represented as the two member `struct`s:
```c
typedef struct {
size_t places; /* number of places in base 2<sup>8*sizeof(type)</sup> */
size_t places; /* number of places in base 2 to the power of (8*sizeof(type)) */
type *number; /* dynamically allocated memory for number */
} bignum
```
### Compile it (with flags to enable all warnings)
Here's where the program shines brighter than a [gamma-ray
@@ -381,19 +417,21 @@ analyzers at my program and make it find the slightest of issues.
Is `clang -Wall -Wextra -Weverything -Dtyp=uint32_t prog.c` all you can
do? Clang has implemented a new warning? Bring it on!
### Execute it
May you win the jackpot!
For least surprising results, the execution character set should be
ASCII. The program computes four bits from every character in `argv[1]` and
interprets them as a hex digit. On ASCII the characters a-f, A-F and 0-9
are converted as expected.
For least surprising results, the execution character set should be ASCII. The
program computes four bits from every character in `argv[1]` and interprets them
as a hex digit. In ASCII the characters `a-f`, `A-F` and `0-9` are converted as
expected.
This means however, that the program accepts __any string__, turns it
into a starting number (which is output as the first line), and starts
crunching. Nothing stops you from executing
```sh
./prog "$(cat prog.c)" # Kind of quine?
./prog "$(cat rules guidelines)" # A jackpot? Maybe next year...
@@ -402,9 +440,10 @@ crunching. Nothing stops you from executing
In a certain way, the program is character set and encoding agnostic.
### Assumptions made
* The `EOF` macro from `<stdio.h>` must expand to negative one since it is used
* The `EOF` macro from `<stdio.h>` must expand to `-1` since it is used
to decrement a pointer and do some other math.
None of the tools catches this one. The program self-protects against unusual
systems with `#if EOF + __STDC__` followed by `#error goofy!`. In the rare event
@@ -414,12 +453,14 @@ your system is goofy, replace all `EOF` tokens with `(-1)` and remove the
While the program works best when bytes/characters are octets and the
number of bits in a type is `sizeof(typ) << 3`, it will work correctly
on 24bit or 36bit systems with 9 bits/byte, or systems where
on 24-bit or 36-bit systems with 9 bits/byte, or systems where
`sizeof(typ)` is 1 even for `int` and so on. On such systems, it will only
use 8 * `sizeof(typ)` bits per place. It does not work when `CHAR_BIT <= 7`.
use `8 * sizeof(typ)` bits per place. It does not work when `CHAR_BIT <= 7`.
### Results of various checkers
### cppcheck
The open source static checker [cppcheck](http://cppcheck.sourceforge.net/)
@@ -451,12 +492,11 @@ No hits found.
#### valgrind
The open source dynamic checker [valgrind](http://valgrind.org/)
runs an executable and verifies all memory accesses and (de)allocations for
proper bounds and memory leaks.
Since the program frees all memory in all possible execution paths, even when
it must bail out,
valgrind should be happy. An early version of my program however reported this:
The open source dynamic checker [valgrind](http://valgrind.org/) runs an
executable and verifies all memory accesses and (de)allocations for proper
bounds and memory leaks. Since the program frees all memory in all possible
execution paths, even when it must bail out, valgrind should be happy. An early
version of my program however reported this:
```
valgrind --leak-check=full --show-leak-kinds=all ./prog 6
@@ -486,8 +526,8 @@ valgrind --leak-check=full --show-leak-kinds=all ./prog 6
==14615== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
```
From which I concluded that `printf` allocated a single 4K block for
which no matching free existed. But how to free memory allocated deep
From which I concluded that `printf(3)` allocated a single 4K block for
which no matching `free(3)` existed. But how to free memory allocated deep
down in the guts of the Standard I/O library? After some serious head
scratching it hit me. The only chance I have is telling the system I no
longer want to do I/O, maybe then it would free that buffer. A reading
@@ -528,6 +568,7 @@ valgrind --leak-check=full --show-leak-kinds=all ./prog 6
A squeaky clean valgrind result!
#### FlexeLint
FlexeLint is a commercial lint tool by [Gimpel
@@ -568,7 +609,7 @@ rules](http://doc.hcc-embedded.com/display/CODING/MISRA+Rules) for C
programming. I am proud to report that my program fulfills *almost all*
rules. To assess the few exceptions, one has to understand that MISRA
rules are geared towards embedded systems used in the automotive
industry. That's why features like `malloc` and `printf` are right out.
industry. That's why features like `malloc(3)` and `printf(3)` are right out.
But that's too restrictive for an IOCCC hosted application, so I ignored
these:
@@ -578,7 +619,7 @@ these:
* 20.9 The input/output library stdio.h shall not be used in production code.
* 20.11 The functions abort, exit, getenv, and system from the library stdlib.h shall not be used.
I started out with enabling *all* messages using FlexeLint's `-w4`
I started out with enabling *all* messages using `FlexeLint`'s `-w4`
option and disabling all noise from system headers. Then I dealt with
the remaining messages by addressing them or suppressing them in such a way
that the set of suppressions was minimal. At the end of the day, this is
@@ -652,7 +693,7 @@ what remained:
Which of the rules cause which obfuscation?
MISRA 6.1, "The plain char type shall be used only for the storage and
MISRA 6.1: "The plain `char` type shall be used only for the storage and
use of character values." This forbids using character constants in
expressions other than assignments to `char` objects. A consequence is
that printing digits with `'0' + digit` is not allowed (even though
@@ -666,19 +707,19 @@ because of the "no magic numbers other than powers of two" rule. How is this
an improvement over `printf("%c", '0' + tyr + 7 * (tyr / 10)`, MISRA?
MISRA 6.3 "typedefs that indicate size and signedness should be used in
MISRA 6.3: "`typedef`s that indicate size and signedness should be used in
place of the basic types." Well, if you can't infer the size and
signedness from `typedef int met`, you're not a real C programmer.
MISRA 10.5, "If the bitwise operators `~` and `<<` are applied to an
MISRA 10.5: "If the bitwise operators `~` and `<<` are applied to an
operand of underlying type `unsigned char` or `unsigned short`, the
result shall be immediately cast to the underlying type of the operand."
Because the program must work for any unsigned type chosen for the `typ`
macro, including the narrow types enumerated in the rule, a lot of
redundant casting ensues. It gets worse with the next rule...
MISRA 12.1, "Limited dependence should be placed on the C operator
MISRA 12.1: "Limited dependence should be placed on the C operator
precedence rules in expressions." This requires parentheses for almost
all expressions involving more than one operator, especially those for which
a cast is required, leading to hard to understand expressions such as
@@ -688,17 +729,17 @@ const ser glx = (ser)((asx > (ser)64u) ? (ser)((ser)asx + (ser)8u + (ser)1u) : (
not.not[leu] = (and)((and)not.not[leu] | (and)(((and)glx % (and)16u) << (and)lys));
```
MISRA 14.7, "A function shall have a single point of exit at the end of
MISRA 14.7: "A function shall have a single point of exit at the end of
the function." Sigh. Since I must use eloquent prototypes (8.1, 16.3,
16.4) and static functions (8.10, 8.11), I can only use a few functions.
Everything usually written with an early `return` now cause *another
useless indent level*. The first three `if` statements in `main` cause a
useless indent level*. The first three `if` statements in `main()` cause a
silly 24 character indent. The maximum indent is forced to 8, which is way
too high for a sane function.
MISRA 16.10, "If a function returns error information, then that error
information shall be tested." A cast to void would draw a lint warning, so
I use the `printf` result in expressions,
MISRA 16.10: "If a function returns error information, then that error
information shall be tested." A cast to `void` would draw a lint warning, so
I use the `printf(3)` result in expressions,
```c
lys -= 4 * printf("%c", (met)tyr + 32 + 16 + ((8 + EOF) * ((met)tyr / (8 + 2))));
@@ -715,15 +756,15 @@ lys -= 4;
```
MISRA 13.1, "Assignment operators shall not be used in expressions that
MISRA 13.1: "Assignment operators shall not be used in expressions that
yield a Boolean value." Forbids the idiomatic `if ((p = malloc(n)) ==
NULL)` and requires separate statements, in other words, bloat.
MISRA 16.7, "A pointer parameter in a function prototype should be
declared as pointer to const if the pointer is not used to modify the
MISRA 16.7: "A pointer parameter in a function prototype should be
declared as pointer to `const` if the pointer is not used to modify the
addressed object." in conjunction with lint's "Note 952: Parameter could
be declared const" causes const-poisoning for all functions,
be declared `const`" causes `const`-poisoning for all functions,
```c
static void phe(const ala not);
@@ -733,11 +774,13 @@ met main(met val, const pro *const his[]);
and quite a number of automatic variables.
### Why the "laugh" and "throw up" messages?
The guidelines state "We like programs that: make us laugh and/or throw
up :-) (humor really helps!)"
### If you have a 128 bit type
If your compiler supports a 128 bit wide type (e.g. clang, gcc) then
@@ -757,24 +800,25 @@ clang -Dtyp=uint64_t -o prog64 prog.c
clang -std=c89 -Dtyp="unsigned long" -o prog89 prog.c
```
This works because the program has no need for corresponding `SCN` or
`PRI` macros to do the scanning and printing of variables of these
types. With a 128 bit type the program can represent numbers up to
340282366920938463463374607431768211457 (3.4 * 10<sup>39</sup>) as a
single "place", enough to explore yet untested numbers for the rest of
your life.
This works because the program has no need for corresponding `SCN` or `PRI`
macros to do the scanning and printing of variables of these types. With a 128
bit type the program can represent numbers up to
340282366920938463463374607431768211457 (`3.4 *
1000000000000000000000000000000000000000`) as a single "place", enough to
explore yet untested numbers for the rest of your life.
### How big a number can I test with 4 GB of RAM?
The number of hex digits in the start number is limited by `ARG_MAX`,
probably minus some overhead for the environment variables (use
[`env`(1)](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/env.html)
to trim your environment). In bits this leaves you with 2<sup>4 *
ARG_MAX</sup>.
[env(1)](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/env.html)
to trim your environment). In bits this leaves you with `2 to the power of (4 *
ARG_MAX)`.
The algorithm requires two bignums in memory for addition.
The algorithm requires two `bignum`s in memory for addition.
If you hit a divergent number, this will cause out-of-memory ("laugh")
somewhere near 2<sup>16,000,000,000</sup> (4GB/2 * 8bits/byte).
somewhere near 2<sup>16,000,000,000</sup> (`4GB/2 * 8bits/byte`).
Sadly, I don't have a test case :-)
How long would it take to overflow the *Not Overflowing Type*? Lets
@@ -782,11 +826,11 @@ assume we're processing 2GB numbers. The program copies, shifts by one,
adds and increments 2GB long bit strings, each time completely thrashing
the data cache -- at *all* levels. We have a fast machine that can do an
iteration in one second, on average. To make things easy, we round up
3*n* + 1 to 4*n*, and assume we never need to divide by two (which is
`3*n* + 1` to `4*n`, and assume we never need to divide by two (which is
quite optimistic). Then each iteration shifts left by 2. This would take
8 billion seconds, or about 250 years. If you want to get famous, you
better *remove* some of the RAM, use an ancient box, or reduce available
memory resources with the ulimit(1) built-in of your shell.
memory resources with the `ulimit(1)` built-in of your shell.
For all intents and purposes, the *Not Overflowing Type* keeps the promise!
2015/schweikhardt/try.sh
Executable
+51
View File
@@ -0,0 +1,51 @@
#!/usr/bin/env bash
#
# try.sh - demonstrate IOCCC winner 2015/schweikhardt
#
# 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 19" 1>&2
./prog 19
read -r -n 1 -p "Press any key to run: ./prog 2410 (space = next page, q = quit): "
echo 1>&2
./prog 2410 | less -EXF
read -r -n 1 -p "Press any key to run: ./prog abfff (space = next page, q = quit): "
echo 1>&2
./prog abfff | less -EXF
read -r -n 1 -p "Press any key to run: ./prog 27f8cebf (space = next page, q = quit): "
echo 1>&2
./prog 27f8cebf | less -EXF
read -r -n 1 -p "Press any key to run: ./prog 246f8fddf (space = next page, q = quit): "
echo 1>&2
./prog 246f8fddf | less -EXF
read -r -n 1 -p "Press any key to run: ./prog 2e95ab51ffea9de (space = next page, q = quit): "
echo 1>&2
./prog 2e95ab51ffea9de | less -EXF
read -r -n 1 -p "Press any key to run: ./prog e6a5c22fd7bde9f (space = next page, q = quit): "
echo 1>&2
./prog e6a5c22fd7bde9f | less -EXF
read -r -n 1 -p "Press any key to run: ./prog 1b7dd73a937485bf (space = next page, q = quit): "
echo 1>&2
./prog 1b7dd73a937485bf | less -EXF
read -r -n 1 -p "Press any key to run: ./prog 7d3237680d190a77e53751b (space = next page, q = quit): "
echo 1>&2
./prog 7d3237680d190a77e53751b | less -EXF
read -r -n 1 -p "Press any key to run: ./prog 302ab3d052fb87c06228d249581be0e4 (space = next page, q = quit): "
echo 1>&2
./prog 302ab3d052fb87c06228d249581be0e4 | less -EXF
echo 1>&2
read -r -n 1 -p "Press any key to run ./prog with a googol (10^100) (space = next page, q = quit): "
echo 1>&2
./prog 1249AD2594C37CEB0B2784C4CE0BF38ACE408E211A7CAAB24308A82E8F10000000000000000000000000 | less -EXF
bugs.md
+53
View File
@@ -3061,6 +3061,37 @@ If you want to try and fix this (mis)feature, you are welcome to try.
# 2015
## 2015 hou
### STATUS: INABIAF - please **DO NOT** fix
### Source code: [2015/hou/prog.c](2015/hou/prog.c)
### Information: [2015/hou/README.md](2015/hou/README.md)
The author stated:
--
Hard requirements:
* The platform must implement the `double` type as IEEE754-compliant 64-bit
floating point numbers. The 80-bit intermediate format used by x87 is
considered as an violation of this. The code should print an error message on
such platforms.
* The program must start with the CPU / FPU in round-to-nearest mode.
Soft requirements:
* The compiler must respect `volatile`. The code is formatted to warn about
that, though.
* The printed result is only correct on little-endian machines. The program
takes care to warn about this issue after printing an incorrect big-endian
result. Error messages become garbled, though.
--
## 2015 mills2
### STATUS: INABIAF - please **DO NOT** fix
@@ -3073,6 +3104,28 @@ is not compressed data it's likely to crash.
The program depends on little endian systems.
## 2015 schweikhardt
### STATUS: INABIAF - please **DO NOT** fix
### Source code: [2015/schweikhardt/prog.c](2015/schweikhardt/prog.c)
### Information: [2015/schweikhardt/README.md](2015/schweikhardt/README.md)
The program assumes that `EOF` is `-1`. This can be fixed but at this time it is
uncertain if it should be.
The author also stated:
--
While the program works best when bytes/characters are octets and the
number of bits in a type is `sizeof(typ) << 3`, it will work correctly
on 24-bit or 36-bit systems with 9 bits/byte, or systems where
`sizeof(typ)` is 1 even for `int` and so on. On such systems, it will only
use `8 * sizeof(typ)` bits per place. It does not work when `CHAR_BIT <= 7`.
--
# 2016
There was no IOCCC in 2016.
thanks-for-help.md
+5
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@@ -3884,6 +3884,11 @@ past).
[Cody](#cody) added the [try.sh](/2015/muth/try.sh) script.
## <a name="2015_schweikhardt"></a>[2015/endoh3](/2015/schweikhardt/prog.c) ([README.md](/2015/schweikhardt/README.md]))
[Cody](#cody) added the [try.sh](2015/schweikhardt/try.sh) script.
## <a name="2015_yang"></a>[2015/yang](/2015/yang/prog.c) ([README.md](/2015/yang/README.md]))
[Cody](#cody) fixed an unfortunate typo in the Makefile that was preventing some of the