path: root/support/convert/convert.dtx

\def\fileversion{1.0b}
\def\filedate{1991/07/08}
\def\docdate{1991/07/08}

%% \CheckSum{556}
%% \CharacterTable
%%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
%%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
%%   Digits        \0\1\2\3\4\5\6\7\8\9
%%   Exclamation   \!     Double quote  \"     Hash (number) \#
%%   Dollar        \$     Percent       \%     Ampersand     \&
%%   Acute accent  \'     Left paren    \(     Right paren   \)
%%   Asterisk      \*     Plus          \+     Comma         \,
%%   Minus         \-     Point         \.     Solidus       \/
%%   Colon         \:     Semicolon     \;     Less than     \<
%%   Equals        \=     Greater than  \>     Question mark \?
%%   Commercial at \@     Left bracket  \[     Backslash     \\
%%   Right bracket \]     Circumflex    \^     Underscore    \_
%%   Grave accent  \`     Left brace    \{     Vertical bar  \|
%%   Right brace   \}     Tilde         \~}
%%
%\iffalse
%
%% TeX utility `convert' to use with plainTeX or LaTeX v2.09
%% Copyright (C) 1991 by Bernd Raichle.
%
% Copying of this file is authorized only if either
% (1) you make absolutely no changes to your copy, including name, or
% (2) if you do make changes, you name it something other than
%     convert.tex, convert.doc, or convert.dtx.
% This restriction helps ensure that all utilities developed here
% remain identical.
%
% Error reports please to:
%        Bernd Raichle
%        Stettener Str. 73
%        D-73732 Esslingen
%        Federal Republic of Germany
% Email: raichle@.informatik.uni-stuttgart.de
%
%
%\fi
%
% \changes{v1.0b}{21 april 1999}{small doc changes;
%                 replaced extension doc with dtx;
%                 license conditions changed to LPPL}
% \changes{v1.0a}{8 july 1991}{revised documentation}
% \changes{v0.6}{6 july 1991}{replaced `input by `read
%                             when reading the input file}
% \changes{v0.5}{18 june 1991}{added conversion table in a file}
% \changes{v0.4}{14 may 1991}{added conversion to macros}
% \changes{v0.3}{22 april 1991}{plain\TeX\ version, fixed NUL-char bug}
% \changes{v0.2}{27 march 1991}{added C-I expansion and
%                               C-M/C-J distinction}
% \changes{v0.1}{16 march 1991}{first version (for \LaTeX)}
%
%
% \DoNotIndex{\fileversion,\filedate,\docdate}
% \DoNotIndex{\catcode,\def,\let,\string,\immediate,\write,\read}
% \DoNotIndex{\ifx,\else,\fi,\expandafter,\csname,\endcsname,\end}
% \DoNotIndex{\everypar,\errhelp,\errmessage,\inputlineno,\ifnum}
% \DoNotIndex{\errorcontextlines,\afterassignment,\jobname,\relax}
% \DoNotIndex{\chardef,\openout,\closeout,\openin,\closein,\the}
% \DoNotIndex{\message,\begingroup,\endgroup,\lowercase,\advance}
% \DoNotIndex{\gdef,\lccode,\xdef,\noexpand,\global,\ifcase,\or}
% \DoNotIndex{\uppercase,\uccode,\count,\endlinechar,\ifeof}
% \DoNotIndex{\endinput,\^^@}
% \DoNotIndex{\sixt@@n,\nullfont,\count@,\z@,\@ne,\tw@,\thr@@,\m@ne}
% \DoNotIndex{\sixt@@n,\@cclvi,\loop,\repeat,\space,\empty,\active}
% \DoNotIndex{\undefined,\newcount,\newwrite}
%
%
% \title{Convert -- a \TeX-file converter for
%        \TeX~3.0\thanks{This file has version number \fileversion,
%        last revised \filedate, documentation dated \docdate.}}
% \author{Bernd Raichle}
%
% \address{Stettener Str.~73\\
%          D-73732 Esslingen\\
%          Federal Republic of Germany}
% \netaddress{raichle@informatik.uni-stuttgart.de}
% \signature{\signaturemark Bernd Raichle\\
%         \theaddress1}
%
% \date{June 12, 1991}
%
% \maketitle
%
% \begin{abstract}
%   The release of \TeX~3.0 and use of national character sets
%   arise one problem: the portability of texts.  Users should be
%   able to use an customized \TeX\ which allows the input and
%   output of national characters.
%   The exchange of texts with extended character set is
%   supported by \TeX\ if you are using the \verb+^^x+ notation
%   described in the \TeX{}book.  This utility written in \TeX\
%   converts a text to this notation.
% \end{abstract}
%
%
% \section{External and internal character representation}
%
% \subsection{Basics}
%
% {\small\it
% {\S 17. The character set.}\\
% In order to make \TeX\ readily portable to a wide variety of
% computers, all of its input text is converted to an internal eight-bit
% code that includes standard ASCII, the ``American Standard Code for
% Information Interchange.''  This conversion is done immediately when each
% character is read in. Conversely, characters are converted from ASCII to
% the user's external representation just before they are output to a
% text file.
% \par\smallskip
% {\S 23.}\\
% The ASCII code is ``standard'' only to a certain extent, since many
% computer installations have found it advantageous to have ready access
% to more than 94 printing characters. Appendix~C of {\sl The \TeX book\/}
% gives a complete specification of the intended correspondence between
% characters and \TeX's internal representation.
% \par
% \hbox to\hsize{\hfil\rm from \TeX: The Program.}\par}
%
% \medskip
%
% \TeX\ reads the input file line by line and converts between the internal
% character set (a superset of ASCII) and the user's external character
% set with the help of two arrays named {\tt xord} and {\tt xchr}.
%
% Each character~$c_e$ read from the file or the terminal is replaced
% by the (internal) character $c_i = \mathop{\rm xord}[c_e]$.
%
% When \TeX\ writes a character~$c_i$ to a file or the terminal the
% string {\tt str\_pool$[c_i]$} is used to produce visible strings for
% unprintable characters.  Each (internal) character~$c_j$ from this
% string is replaced by the (external) character
%  $c_e = \mathop{\rm xchr}[c_j]$.
%
% \medskip
%
% The conversions between the internal and the external character set
% are system dependent. A text written on system~$A$ has to be translated
% when it is transferred to system~$B$ with another external character set.
%
% {\catcode`\^=12
% A text is portable only if both systems use the same mapping from their
% external character set to ASCII characters $32-127$\footnote{Additionally
% the mapping to ASCII characters with special functions like NUL, CR,
% LF,\ldots has to be equal too.} and the text uses no other characters.
% \TeX\ supports further the use of non-ASCII characters
% if a special notation is used:  when reading text the character sequence
% \verb=^^x= is replaced by one character with internal code $x-64$ or
% $x+64$.  Additionally \TeX~3 allows the notation \verb=^^xy= where
% \verb=xy= are two lowercase hexadecimal digits. The four character sequence
% is replaced by one character with internal code equal to the
% hexadecimal value.\footnote{The characters in {\tt ^^x} and {\tt ^^xy}
% are first translated to their internal representation before the
% replacement is done.  Additionally the category code of character {\tt ^}
% has to be~5.  For example \LaTeX's {\tt verbatim} environment change the
% category code to~12.}}
%
%
% \subsection{Example}
%
% Assume that you have two \TeX\ versions and the external character set
% uses ASCII for character codes~$< 128$.  The code of the character
% {\tt \"a} is {\it 132} (or hexadecimal \verb="84=) and \TeX's internal
% code should be {\it 228} (or \verb="e4=) for this character.
%
% Version~1 uses idendity as mapping between external and internal
% character codes, all characters not in $32-127$ are printed in
% \verb=^^x= notation.  Version~2 maps the character {\tt \"a} and
% prints this character as {\tt \"a}.
%
% The interesting parts of the arrays in both versions are:
%
% \hbox to\hsize{\hfil
% \begin{tabular}{|rlr|rlr|}
% \hline
% \multicolumn{3}{|l|}{\small Version 1:} &
% \multicolumn{3}{|l|}{\small Version 2:} \\ \hline
%        xord[132]&=&132         &      xord[132]&=&228 \\
%                 & &            &      xchr[228]&=&132 \\
%   str\_pool[132]&=&\verb=^^84= & str\_pool[228]&=&{\tt \"a} \\
% \hline
% \end{tabular}\hfil}
%
% \medskip
%
% If version~1 reads the character {\tt \"a} it is translated to internal
% code~$132$.  When this character is printed \TeX\ writes the string
% \verb=^^84= to the output and translates each of the four characters
% of this string to their external representation.
%
% Using version~2 the character {\tt \"a} is translated to internal
% code~$228$ when it is read.  \TeX\ writes the character~$228$ as string
% {\tt \"a} (an {\tt \"a} with code $228$!).  This character is replaced
% by its external code~$132$ and the user sees the character {\tt \"a}.  
%
% \medskip
%
% The \verb=^^xy= notation can be used in both versions to get the same
% internal character code for the {\tt \"a}.
% \TeX\ replaces the character sequence \verb=^^e4= by one character with
% internal code \verb="e4= ($= 228$).
% This character is written as explained above, i.e., version~1 prints
% \verb=^^e4=, version~2 prints {\tt \"a}.
%
%
% \section{Usage}
%
% To use this utility just type ``\verb=tex convert='' or
% ``\verb=latex convert=''.
% You are prompted for the conversion type and the input and output
% filename.  This tool checks if you want to override your input file
% but their is no check for an existing output file.
% When an empty output filename is given the output is written only to
% the terminal and in the log-file.
%
% In the current version of this tool there are two types for
% conversion.
% Type~1 converts all unprintable characters to the \verb=^^z=
% or \verb=^^xy= notation.
% Type~2 additionally reads the file {\tt convert.tbl} with
% user-defined translation entries.  Both conversion types expands
% {\tt TAB} characters and ignores additional {\tt LF} and {\tt CR}
% characters in a line with a warning.
%
% \bigskip
%
% The translation table in {\tt convert.tbl} is read without
% expansion of the control sequences given.  All characters except
% `invalid' and `ignored' characters can be used in the replacement
% string.  Another exception is the comment character `\%' which can
% be used to allow comments in this file.
%
% For each translation you wrote a line
%
%  \begin{tabular}{p{2cm}p{2cm}l}
%    & \it charnum & \it replacement text
%  \end{tabular}
%
% {\em charnum} is one of the formats allowed for character numbers
% in \TeX. Note that the replacement text can have unbalanced braces.
%
% \medskip
% {\bf Examples:}
%
% You want to replace the character with internal code $228$ by
% the string \verb={\" a}=.
%
%  \begin{tabular}{p{2cm}p{2cm}l}
%     & {\tt 228} & \verb={\" a}=
%  \end{tabular}
%
% If you don't know the internal character code of an {\tt \"a}
% you should specify this character as {\it charnum}.  The
% translation of the {\tt \"a} is done when reading the file
% {\tt convert.tbl} and when reading the input file with the same
% input/output translation.
%
%  \begin{tabular}{p{2cm}p{2cm}l}
%     & {\tt \"a} & \verb={\" a}=
%  \end{tabular}
%
% You have just received a file where all {\tt \"a} characters are
% printed as {\tt \v D} and you want to convert it to your external
% character code.
%
%  \begin{tabular}{p{2cm}p{2cm}l}
%     & {\tt \v D} & {\tt \"a}
%  \end{tabular}
%
%
%\StopEventually{\makesignature\PrintIndex}
%
% \section{The implementation}
%
%    \subsection{Initial Phase}
%
%    Because we want to use internal macros, set the category code
%    of \verb=@= to `letter'.
%    \begin{macrocode}
\catcode`@=11
%    \end{macrocode}
%
%    This utility can be used with plain\TeX\ and \LaTeX.  For plain\TeX\
%    we copy some useful things from `latex.tex'.
%    \begin{macrocode}
\newwrite\@unused
\def\typeout#1{{\let\protect\string\immediate\write\@unused{#1}}}
\def\@strip#1#2 \@gobble{\def #1{#2}}
\def\@defpar{\par}
\def\@iden#1{#1}
\def\@gobble#1{}
\def\typein[#1]#2{\typeout{#2}\read\sixt@@n to#1%
  \ifx #1\@defpar \def#1{}\else
    \@iden{\expandafter\@strip\expandafter #1#1\@gobble\@gobble} \@gobble
  \fi}
%    \end{macrocode}
%
%    The first real thing to do is to write the current version of this file.
%    \begin{macrocode}
\typeout{TeX Utility `convert' version \fileversion\space <\filedate> (br)}
\typeout{English documentation dated <\docdate> (br)}
%    \end{macrocode}
%
%    \LaTeX\ redefines \verb=\end=.  We define a new macro to end this
%    job which works for plain\TeX\ and \LaTeX.  The first \verb=\@@end=
%    has the meaning \verb=\relax= if we are using plain\TeX, otherwise
%    it's plain\TeX's \verb=\end= which is saved in \verb=\@@end= by
%    \LaTeX.
%    \begin{macro}{\endofjob}
%    \begin{macrocode}
\def\endofjob{\csname @@end\endcsname \end}
%    \end{macrocode}
%    \end{macro}
%
%    This utility should never produce a DVI-file.  For the case that this
%    is not true\footnote{This should only happen when this tool is
%    corrupted!}, we produce an error message.
%    \begin{macrocode}
\everypar{\errhelp{This TeX utility should not produce any dvi output.}%
  \errmessage{Internal Error 1. -- Please fix me!}}
\nullfont
%    \end{macrocode}
%
%    We use the fact that \TeX~3 can distingiush 256~different
%    input characters.
%    If the user has started a pre-3 \TeX\ we exit with an error message
%    to inform the user about the need of a newer \TeX\ version.
%    \begin{macrocode}
\def\sorry{%
  \typeout{******************************************}
  \typeout{* Sorry, you need TeX 3 for this Utility *}
  \typeout{******************************************}
  \endofjob}
%    \end{macrocode}
%    The new version of `plain.tex' and `lplain.tex' allocates normal
%    counter for the new \TeX~3 counter if you are using a pre-3 \TeX.
%    We use the fact that \verb=\inputlineno= is set to a negative value
%    after allocating the normal counter and that this counter is not
%    changed.  For \TeX~3 it contains a positive value.
%    \begin{macrocode}
\newif\iftexthree \texthreetrue
\ifx\undefined\inputlineno
  \texthreefalse
\else
  \count@=\inputlineno
  \ifnum\inputlineno<\z@
    \texthreefalse
  \else\ifnum\inputlineno=\count@
    \texthreefalse
  \fi\fi
\fi
\iftexthree \else \expandafter\sorry\fi
%    \end{macrocode}
%
%    If an error occurs it's unnecessary to print more than a few lines.
%    \begin{macrocode}
\errorcontextlines=\m@ne
%    \end{macrocode}
%
%    \subsection{User Input}
%
%    We need the character \verb=^= as a normal character with category
%    code `other'.
%    \begin{macrocode}
\catcode`^=12
%    \end{macrocode}
%
%    Inform the user about the usefullness of this file.
%    \begin{macrocode}
\typeout{}
\typeout{********************************************************}
\typeout{ This program converts text-files with 8bit-characters}
\typeout{ into text-files with TeX's ^^xx syntax or TeX macros}
\typeout{ for these characters.}
\typeout{********************************************************}
\typeout{}
%    \end{macrocode}
%
%    Ask the user what type of conversion should be done.  Currently
%    this file supports the conversion of unprintable characters in
%    \TeX's \verb=^^xx= syntax or user-defined replacement.
%
%    The type of conversion is saved in the counter \verb=\convtype=.
%    \begin{macro}{\convtype}
%    \begin{macrocode}
\newif\iffehler
\newcount\convtype
%    \end{macrocode}
%    \end{macro}
%    The assignment to \verb=\convtype= is not error-prove. If the user
%    types more than an integer \TeX\ reports an error.
%    \begin{macrocode}
\def\getnumber{\afterassignment\gobblerest\count@=}
\def\gobblerest#1\lineend{}
\loop
  \typeout{ Should I convert 8bit characters to...}%
  \typeout{ \space 1) ^^x notation or}%
  \typein[\conversion]%
          { \space 2) macros calls (defined in `convert.tbl')}%
%    \end{macrocode}
%    If the user types nothing, convtype should be set to zero.
%    \begin{macrocode}
  \getnumber\conversion \space 0 \lineend
  \convtype=\count@
  \fehlertrue
  \ifnum\convtype>\z@ \ifnum\convtype<\thr@@ \fehlerfalse \fi\fi
  \iffehler
    \typeout{ !! Please type 1 or 2 !!}\typeout{}%
\repeat
%    \end{macrocode}
%    We ask the user about the input and the new output
%    filename.
%    \begin{macro}{\infilename}
%    \begin{macro}{\outfilename}
%    \begin{macrocode}
\typeout{}
\typein[\infilename]{First type the name of your input file:}
\typeout{}
\typein[\outfilename]{Now type the name of your output file:}
\typeout{}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%    We should avoid the case that the user overwrites the input file.
%    \begin{macrocode}
\ifx\infilename\outfilename
  \typeout{}
  \typeout{!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!}
  \typeout{! Not possible to read from and write to the same file !}
  \typeout{!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!}
  \expandafter\endofjob
\fi
%    \end{macrocode}
%
%    If the output filename is empty, we output into the log-file
%    and on the terminal. Otherwise we open the file given in
%    \verb=\outfilename= for output.
%    \begin{macrocode}
\newwrite\outstream
\ifx\outfilename\empty
  \typeout{Output to \jobname.log and online.}
  \typeout{------------------------------------------------------------}
  \chardef\outstream=\sixt@@n
\else
  \immediate\openout\outstream \outfilename \relax
\fi
%    \end{macrocode}
%
%    \subsection{Collect and output one Line}
%
%    To access unprintable characters in a portable way in this file we
%    change the category code of \verb=~= to~7.  Additionally a character
%    with category code `active' is used very often.
%    \begin{macrocode}
\catcode`~=7
\catcode`$=\active
%    \end{macrocode}
%
%    We save the current incomplete line in the token register
%    \verb=\currentline= and maintain an input line counter.
%    \begin{macrocode}
\newtoks\currentline \currentline={}
\newcount\lineno
%    \end{macrocode}
%
%    We output a complete line with \verb=\finish@line=. When the output
%    is written in a file, we inform the user about the current processed
%    input line number.
%    \begin{macro}{\finish@line}
%    \begin{macrocode}
\ifx\outfilename\empty
  \def\finish@line{\immediate\write\outstream{\the\currentline}%
    \currentline{}\outputpos\z@}
\else
  \def\finish@line{\immediate\write\outstream{\the\currentline}%
    \currentline{}\outputpos\z@\message{\the\lineno}}
\fi
%    \end{macrocode}
%    \end{macro}
%
%    Tabs should be expanded so we need another counter.
%    \begin{macrocode}
\newcount\outputpos \outputpos=\z@
%    \end{macrocode}
%
%    The macro \verb=\expand@tab= inserts space characters in the input
%    stream until a tab position is reached.  We need an active space
%    character, so we use a little trick with \verb=\lowercase=.
%    \begin{macro}{\expand@tab}
%    \begin{macrocode}
\begingroup\lccode`$=32
\lowercase{\endgroup
\def\expand@tab{%
  \count@\outputpos
  \loop \ifnum\count@>7 \advance\count@ -8\repeat
  \loop \ifnum\count@<8 \advance\count@\@ne $\repeat
}
} % end of lowercase
%    \end{macrocode}
%    \end{macro}
%
%    With the macro \verb=\defoutstring= we define the character in argument~1
%    to write the string given in argument~2 of length given in argument~3.
%    The definition is done with \verb=\xdef= because the second argument can
%    contain some other macros (e.g. \verb=\hexnum=) which have to be expanded.
%
%    But before this is done there is a special case where
%    \verb=\lowercase= doesn't work.
%    \begin{macrocode}
\begingroup \catcode`\~~@=\active
\gdef~~@{\currentline\expandafter{\the\currentline ^^@}%
     \advance\outputpos\thr@@}
\endgroup
%    \end{macrocode}
%    \begin{macro}{\defoutstring}
%    \begin{macrocode}
\def\defoutstring#1#2#3{\ifnum#1=\z@ \else
  \begingroup \lccode`$=#1\relax
  \lowercase{\endgroup\xdef$}%
    {\currentline\noexpand\expandafter{\noexpand\the\currentline #2}%
    \advance\outputpos\noexpand#3}%
  \fi
}
%    \end{macrocode}
%    \end{macro}
%
%    To assign control sequences to characters we use two additional macros.
%    \begin{macro}{\defout}
%    \begin{macrocode}
\def\defout#1#2{\lccode`$=#1\relax
  \lowercase{\gdef$}{#2}}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\letout}
%    \begin{macrocode}
\def\letout#1#2{\lccode`$=#1\relax
  \lowercase{\global\let$}#2}
%    \end{macrocode}
%    \end{macro}
%
%    For characters greater than~127, we need a hexdecimal representation
%    with lowercase characters. The macro has to be expandable.
%    \begin{macro}{\hexnum}
%    \begin{macrocode}
\def\hexnum#1{\ifcase#1 0\or 1\or 2\or 3\or 4\or 5\or 6\or 7\or
  8\or 9\or a\or b\or c\or d\or e\or f\fi}
%    \end{macrocode}
%    \end{macro}
%
%    \subsection{Definition of active Characters}
%
%    We define macros for all of the 256 characters in TeX's internal
%    character representation.
%
%    Here is the first use of \verb=\defoutstring=: We define the printable
%    character in \TeX's character positions 32--127 to output themself.
%    \begin{macrocode}
\catcode`*=12
\count@=32
\loop
  \lccode`*=\count@
  \ifnum\count@<127
     \lowercase{\defoutstring\count@*{\@ne}}
     \advance\count@\@ne
\repeat
\defoutstring{127}{^^?}\thr@@
%    \end{macrocode}
%
%   The characters in position 0--31 are output in the form \verb=^^X=.
%    \begin{macrocode}
\count@=\@ne \count\thr@@=`A
\loop
  \uccode`*=\count\thr@@
  \ifnum\count@<32
     \uppercase{\defoutstring\count@{^^*}}\thr@@
     \advance\count@\@ne \advance\count\thr@@\@ne
\repeat
%    \end{macrocode}
%
%    The character positions 128--255 (these are new in \TeX~3) are
%    written in the form \verb=^^xx=.
%    \begin{macrocode}
\count@=128
\count\@ne=8 \count\tw@=0 % hex-counter
\loop
  \ifnum\count@<\@cclvi
     \defoutstring\count@
        {^^\hexnum{\the\count\@ne}\hexnum{\the\count\tw@}}4
     \advance\count@\@ne
     \ifnum\count\tw@>14
       \count\tw@\z@ \advance\count\@ne \@ne
     \else
       \advance\count\tw@ \@ne
     \fi
\repeat
%    \end{macrocode}
%
%    \subsection{User-defined character translation}
%
%    The user can define his own character translation.  The translation
%    are specified in a file called `convert.tbl' which contains one
%    translation per line.  Each line begins with the character number
%    (with the syntax of \TeX's \verb=<charnum>=), the rest of the line
%    is the replacement string.
%
%    After the conversion string is read in we need to know the
%    length of this string.
%    \begin{macro}{\getlength}
%    \begin{macro}{\lengthloop}
%    \begin{macrocode}
\newcount\length
\def\getlength{\afterassignment\lengthloop\let\next= }
\def\lengthloop{%
  \ifx\next\empty
  \else
    \advance\length\@ne
    \expandafter\getlength
  \fi
}
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%
%    For each line we get at first the character number and the length
%    of the translation string.  With the macro \verb=\defoutstring=
%    we redefine the corresponding macro to produce this string.
%    \begin{macro}{\processline}
%    \begin{macrocode}
\def\processline#1 #2\lineend{\length=\z@
  \getlength#2\empty \getnumber#1\space -1 \lineend
  \defoutstring\count@{#2}\length
}
%    \end{macrocode}
%    \end{macro}
%
%    Now we define the macro to read the file `convert.tbl'.
%    When reading the file we have to set most of the letter to
%    category codes `letter' or `other' to suppress expansion and
%    errors.  Only the category codes of a few letters are left
%    unchanged.
%
%    \begin{macro}{\readfile}
%    \begin{macrocode}
\newif\ifmore \moretrue
\def\readfile{\begingroup
  \count@=\z@
  \loop
    \ifnum\count@<\@cclvi
      \ifnum\catcode\count@<9
        \catcode\count@ 12
      \else\ifnum\catcode\count@=\active
        \catcode\count@ 12
      \fi\fi
      \advance\count@ \@ne
  \repeat
  \loop
    \endlinechar\m@ne
    \read\@ne to \curline
    \endlinechar`~~M
    \ifx\curline\empty % ignore empty lines
    \else
      \expandafter\processline\curline\lineend
    \fi
    \ifeof\@ne \morefalse \fi
    \ifmore
  \repeat
\endgroup}
%    \end{macrocode}
%    \end{macro}
%
%    And here is the place where the file is read.  But this is
%    only done if the user has asked for it.
%    \begin{macrocode}
\ifnum\convtype=\tw@
  \openin\@ne convert.tbl\relax
  \ifeof\@ne
     \typeout{I can't find file `convert.tbl' -- ignored.}%
  \else
    \readfile
    \closein\@ne
  \fi
\fi
%    \end{macrocode}
%
%    And the last action: we define macros for characters with special
%    functions.  These are `line feed', `carriage return' and `tab'.
%    \begin{macrocode}
\letout{9}\expand@tab
\defout{10}{%
  \typeout{!!--> Found ^J in line \the\lineno--I'll ignore all ^J.}%
  \letout{10}\relax}
\defout{13}{%
  \typeout{!!--> Found ^M in line \the\lineno--I'll ignore all ^M.}%
  \letout{13}\relax}
%    \end{macrocode}
%
%    \subsection{Convert the file}
%
%    Now after the character translation is set up we have to make
%    all characters active.  We read the file line by line with TeX's
%    \verb+\read+ primitive.  (If we would \verb+\input+ the file we
%    have to set \verb+\endlinechar+ to signal the end-of-line.)
%
%    \begin{macrocode}
\def\readfile{%
  \read\@ne to\next
  \ifeof\@ne
  \else
    \advance\lineno\@ne
    \next\relax
    \finish@line
    \expandafter\readfile
  \fi
}
%    \end{macrocode}
%
%    \begin{macrocode}
\def\makeactiveandinput{\begingroup
  \count@=\z@
  \loop
    \ifnum\count@<\@cclvi
      \catcode\count@\active
      \advance\count@\@ne
  \repeat
%    \end{macrocode}
%    While reading from the file it is useful to switch off the
%    recognition of the end-of-line character.  This saves us stripping
%    off spaces from the contents of the line.
%    \begin{macrocode}
  \endlinechar=-1
  \openin\@ne \infilename\relax
  \ifeof\@ne
    \typeout{No input file \infilename.}%
  \else
    \lineno\z@
    \readfile
    \closein\@ne
  \fi
  \endlinechar=`~~M
  \ifx\outfilename\empty
    \typeout{------------------------------------------------------------}
  \else
    \immediate\closeout\outstream
  \fi
  \endgroup
  \endofjob
}
%    \end{macrocode}
%    The last task: call the macro. 
%    \begin{macrocode}
\makeactiveandinput
%    \end{macrocode}
%
%    Normally we should never reach this point.
%    \begin{macrocode}
\errhelp{This TeX utility should not reach this point.}%
\errmessage{Internal Error 2. -- Please fix me!}
\endinput
%    \end{macrocode}
% \Finale
\endinput