Add 2011/fredriksson/try.sh + format/typo checks
Before the last command that the try.sh script will do it first tries to set the stack size to unlimited (for the process) and if it fails it won't run the last command as it will likely dump core. Add entry to bugs.md but since there are quite a few things I just linked to the author's remarks (the sections). This can be adjusted another time if necessary.
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@@ -5,6 +5,17 @@ make
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```
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### Bugs and (Mis)features:
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The current status of this entry is:
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```
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STATUS: INABIAF - please **DO NOT** fix
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```
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For more detailed information see [2011 fredriksson in bugs.md](/bugs.md#2011-fredriksson).
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## To use:
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```sh
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@@ -15,13 +26,12 @@ make
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### Try:
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```sh
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./fredriksson -k1 -i POOT < /etc/group
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ulimit -s unlimited
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./fredriksson -k2 -t -n bofuskate < /usr/share/dict/words
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./try.sh
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```
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NOTE: you need to be allowed to change your stack size or else the last command
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will likely cause the program to dump core.
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in the script would likely cause the program to dump core, which is why the
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script checks the exit code of `ulimit` first.
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## Judges' remarks:
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@@ -36,10 +46,12 @@ program and calls it. As an exercise, try writing the compressor.
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## Author's remarks:
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### Approximate grep
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Implements a variant of `grep`.
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### Usage
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To search regexp from file, do:
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@@ -69,8 +81,8 @@ This version of `grep` recognizes two more options, not present in normal
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"`obfuscated`" matches "`obfuscation`"
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with one deletion and two mismatches. Likewise, "`obfuscate`" and
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"`oversimplify`" match with 7 [edit
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operations](https://en.wikipedia.org/wiki/Edit_distance#Formal_definition_and_properties). The default is `-k0`
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(i.e. exact match).
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operations](https://en.wikipedia.org/wiki/Edit_distance#Formal_definition_and_properties).
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The default is `-k0` (i.e. exact match).
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* `-t` Add local transpositions to the set of allowed
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[edit-operations](https://en.wikipedia.org/wiki/Edit_distance#Formal_definition_and_properties).
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@@ -82,7 +94,8 @@ Of course, one could construct a standard
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[regexp](https://www.regular-expressions.info) that matches the same
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patterns, but the problem is that such a regexp grows exponentially in
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size when the number of allowed [edit
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operations](https://en.wikipedia.org/wiki/Edit_distance#Formal_definition_and_properties) is increased.
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operations](https://en.wikipedia.org/wiki/Edit_distance#Formal_definition_and_properties)
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is increased.
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This version does not recognize all regular expressions, but the
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following are allowed:
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@@ -104,11 +117,13 @@ otherwise this is not needed. Note that the syntax differs from standard
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(?) grep a bit, i.e. in plain grep you can use `]` and `-` in bracket
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expressions by putting `]` as the first character, and putting `-` last.
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### Other uses
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* You can use this in place of [cat](https://en.wikipedia.org/wiki/Cat_(Unix)).
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Just say
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```sh
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./fredriksson -k3 cat < file
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```
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@@ -119,6 +134,7 @@ Just say
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./fredriksson -nk3 cat < file
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```
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### Other features
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* It is assumed that the user knows how to feed correct input to the
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@@ -132,6 +148,7 @@ Just say
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liners in IOCCC entries, just adjust your stack size to a suitable
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threshold, and search for "`ioccc`", with option `-vk5`.
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### Limitations and remarks
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* Using warning options (such as `-Wall`) when building gives a lot of warning,
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@@ -142,7 +159,7 @@ Just say
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Please ignore them all, since they just try to tell you that the source
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is obfuscated.
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* Only standard input is handled. And _only_ if stdin comes from a file,
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* Only standard input is handled. And _only_ if `stdin` comes from a file,
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i.e. pipes may or may not work. If you want to count only (`-c` option),
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then this shouldn't be an issue.
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@@ -157,7 +174,7 @@ Just say
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* Depending on the file, it might require a lot of stack space. If the
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program segfaults (because of this), say
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ulimit -s unlimited
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ulimit -s unlimited
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cross your fingers, hope it is enough, and try again.
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@@ -199,26 +216,26 @@ Just say
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corresponding binary after running it, but this feature was removed
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from the submitted entry.)
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* The code demonstrates several useful programming paradigms, such as
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* The code demonstrates several useful programming paradigms, such as:
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- recursion to remove all loops
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- subroutines (`main()` contains several logical subroutines,
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selected by the first argument)
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- function pointers
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* Algorithmically, it incorporates the following
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- (inverse) Burrows-Wheeler transform (used also e.g. in bzip2)
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* Algorithmically, it incorporates the following:
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- (inverse) Burrows-Wheeler transform (used also e.g. in `bzip2(1)`)
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- data compression (really expansion :-), run-length-encoding,
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unary coding (this is why it is expansion rather than compression)
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- approximate string matching
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- dynamic programming to compute the edit distance
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- parallel computation in sequential computers (by packing
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several objects into a single long, to speed up the dynamic
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several objects into a single `long`, to speed up the dynamic
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programming)
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- self extracting, compiling and running code
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* As a C program, it demonstrates that
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- a C subset without reserved words is complete enough,
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(excluding data type specific things (`int`, `char`, `void` ...))
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excluding data type specific things (`int`, `char`, `void` ...)
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- only letters are needed (i.e. the digits `0-9` are not)
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- only one statement is enough to code any program (plus
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variable definitions)
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@@ -255,18 +272,18 @@ Just say
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One reason for this is that the code builds (some of the) constant
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values from string literal `"\b"`, except that the backspace `\b` is not
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escaped like that; the source uses the raw ascii value (010 octal) instead.
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escaped like that; the source uses the raw ASCII value (`010` octal) instead.
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Thus when viewing with cat or something, that backspace erases the leading
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quotation mark. Makes it appear uncompilable, and it is: if you copy-paste
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the cat output from terminal to some editor, save it, the result would not
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compile.
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Some other constants are built from ASCII values of chars.
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Some other constants are built from ASCII values of `char`s.
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Besides of making the code hard to read, all this makes it also quite large.
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* Running it through GNU indent or bcpp (C beautifiers) does not beautify
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it a bit. In fact, indent makes it only worse (at least with the default
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* Running it through GNU `indent(1)` or `bcpp(1)` (C beautifiers) does not beautify
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it a bit. In fact, `indent` makes it only worse (at least with the default
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options). Running it through the preprocessor does basically nothing,
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since no `#define`s are used.
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@@ -276,7 +293,7 @@ Just say
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program exceeds the 2048 limit. However, whitespace is whitespace and
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the rules did not specify that these must be in between the statements.
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A character is a whitespace if `isspace()` returns non-zero value. Even
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if deleting even one of those chars breaks the program! (This does not
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if deleting even one of those chars it breaks the program! (This does not
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apply to the generated source `ag.c`.)
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Executable
+47
@@ -0,0 +1,47 @@
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#!/usr/bin/env bash
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#
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# try.sh - demonstrate IOCCC winner 2011/fredriksson
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#
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# make sure CC is set so that when we do make CC="$CC" it isn't empty. Doing it
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# this way allows us to have the user specify a different compiler in an easy
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# way.
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if [[ -z "$CC" ]]; then
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CC="cc"
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fi
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make CC="$CC" all >/dev/null || exit 1
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# clear screen after compilation so that only the entry is shown
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clear
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echo "$ ./fredriksson -k3 cat < fredriksson.c" 1>&2
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read -r -n 1 -p "Press any key to have the program show its source code: "
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echo 1>&2
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./fredriksson -k3 cat < fredriksson.c
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read -r -n 1 -p "Press any key to continue: "
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echo 1>&2
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read -r -n 1 -p "Press any key to run: ./fredriksson -k1 -i POOT < /etc/group: "
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echo 1>&2
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./fredriksson -k1 -i POOT < /etc/group
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echo 1>&2
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read -r -n 1 -p "Press any key to run: ./fredriksson -ck0 [0-9] < fredriksson.c: "
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echo 1>&2
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./fredriksson -ck0 [0-9] < fredriksson.c
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echo 1>&2
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read -r -n 1 -p "Press any key to run: ./fredriksson -ck0 [0-9] < ag.c: "
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echo 1>&2
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./fredriksson -ck0 [0-9] < ag.c
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echo "Trying to set unlimited stack space for this process..." 1>&2
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ulimit -s unlimited 2>/dev/null
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if [[ "$?" -ne 0 ]]; then
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echo "...couldn't set unlimited stack space, will skip command." 1>&2
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else
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read -r -n 1 -p "Press any key to run: ./fredriksson -k2 -t -n bofuskate < /usr/share/dict/words: "
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./fredriksson -k2 -t -n bofuskate < /usr/share/dict/words
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fi
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@@ -2488,6 +2488,17 @@ tends to result in empty output.
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If you want to try and fix this (mis)feature, you are welcome to try.
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## 2011 fredriksson
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### STATUS: INABIAF - please **DO NOT** fix
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### Source code: [2011/fredriksson/fredriksson.c](2011/fredriksson/fredriksson.c)
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### Information: [2011/fredriksson/README.md](2011/fredriksson/README.md)
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The author stated that there are a number of features and limitations. As the
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list is rather long see [other
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features](2011/fredriksson/README.md#other-features) and [limitations and
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remarks](2011/fredriksson/README.md#limitations-and-remarks) instead.
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## 2011 richards
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@@ -3231,6 +3231,11 @@ Cody added the video file [boing-ball.mp4](2011/eastman) which is the demo the
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author referred to.
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## [2011/fredriksson](2011/fredriksson/fredriksson.c) ([README.md](2011/fredriksson/README.md]))
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Cody added the [try.sh](2011/fredriksson/try.sh) script.
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## [2011/goren](2011/goren/goren.c) ([README.md](2011/goren/README.md]))
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Cody fixed this for macOS. Before the fix it segfaulted. It worked fine under
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