% New version of \listing and \inputverbatim for LaTeX
% Michal Jaegermann - June 1990
%
% These macros derived from similar macros posted in September of 1989 by
% Peter Burgess
% New Zealand Government Department of Scientific and Industrial Research
% Applied Mathematics Division
% (SRWMXPB@WINDY.DSIR.GOVT.NZ)
%
% \listing modifed to a form \listing[#1]#2#3 where
%   #1 [optional] specifies how often line numbers should be printed;
%      a default value is 5, 0 will turn off line numbering
%   #2 is a value for an indent to be aplied to whole listing
%   #3 is a name of an input file - specify an extension, unless .tex
%
% \inputverbatim[#1]#2 is the same as \listing without line numbers
% A default value for an optional indent is set to 0
%
% \inputverbatim and \listing based on \listing from The TeXbook.
% Some things were taken from LaTeX's verbatim environment.

\def\uncatcodespecials{\def\do##1{\catcode`##1=12 }\dospecials}%

\def\listing{\@ifnextchar[{\listv@rb}{\listv@rb[5]}}%
\def\listv@rb[#1]#2#3{\if@minipage\else\vskip\parskip\fi%
  \begingroup\s@tupv@rblist#1#2 \frenchspacing\@vobeyspaces\input#3 \endgroup}%
\def\inputverbatim{\@ifnextchar[{\inv@rb}{\inv@rb[\z@]}}%
\def\inv@rb[#1]#2{\listv@rb[\z@]{#1}{#2}}%

\newcount\lin@no%  number of file lines listed
\newcount\lin@rem% number of lines from the last number

%first parameter  - numbering step
%second parameter - indent size for the whole included text
\def\s@tupv@rblist#1#2{%
  \tt%
  \leftskip#2\rightskip\z@%
  \parindent\z@\parfillskip\@flushglue\parskip\z@%
  \def\par{\leavevmode\egroup\box0\endgraf}%
  \obeylines \uncatcodespecials%
  \catcode`\`=\active \catcode`\^^I=\active%
  \lin@no=0 \lin@rem=0
  \everypar{%
    \ifnum#1>0
    \advance\lin@no by1 \advance\lin@rem by1
    \ifnum\lin@rem=#1 \lin@rem=0
    \llap{\scriptsize\it\the\lin@no\ \ }%
    \fi\fi%
    \startb@x}}%

\def\startb@x{\setbox0=\hbox\bgroup}%

{\catcode`\`=\active \gdef`{\relax\lq}}%

% code to make tabs work in verbatim.

\newdimen\w \setbox0=\hbox{\tt\space} \w=8\wd0 % tab amount
{\catcode`\^^I=\active%
  \gdef^^I{\leavevmode\egroup%
    \dimen0=\wd0 % the width so far, or since the previous tab
    \divide\dimen0 by\w
    \multiply\dimen0 by\w % compute previous multiple of \w
    \advance\dimen0 by\w  % advance to next multiple of \w
    \wd0=\dimen0 \box0 \startb@x}}
%% end