program bookprint; {print both sides of paper}
{ author: Russell Whitaker    Dec. 25, 2000
  released under terms of gnu gpl }
 
uses gpc;          {for execute command}

{$define ESC char(27)}
const
  TABS = "\t\t\t\t\t\t\t\t\t\t";
  TOF = "\f";
  MaxLines = 59;        {58 plus one for page number}
  Maxlen   = 90;        {maximum line length without warning message}
  AddBlank = 30;        {for printer with push feed}
 
{-- printer specific values - setup for panasonic kx-p2123 in epson mode --}
  LQ_R_E = ESC + char(1) + ESC + 'k' + char(0) + ESC + 'M'; {LQ, roman, elite}
 
  {set left margin in 6 spaces, rt margin full}
  MarginOdd  = ESC + 'l' + char(6) + ESC + 'Q' + char(96);
 
  {set left margin back to begining and rt margin in 6 spaces}
  MarginEven = ESC + 'l' + char(0) + ESC + 'Q' + char(90);
 
  B_R = char(7) + char(7) + ESC + '@';          {bells + reset printer}
 
var
  filenam   : string ( 80 );
  InputFile : text;
  LST_odd, LST_even: text;
  errcode   : integer;
  IsEven    : boolean = FALSE;
  TxtLine   : string ( 512 );
  LineCount : integer = 0;
  PageCount : integer = 1;
  ch        : char;

procedure NewPage;
begin
  while ( not EOF( InputFile )) and ( length( TxtLine ) = 0 ) do
    readln( Inputfile, TxtLine );  { discard blank lines }
  If length( TxtLine ) > 0 then
  begin
    Inc( PageCount );
    IsEven := not IsEven;
    if IsEven then
    begin
      if PageCount > 2 then
        write( LST_even, TOF )
      else
        write( LST_even, LQ_R_E, MarginEven );
      writeln( LST_even, PageCount );
      writeln( LST_even, TxtLine );
    end
    else
    begin
      if PageCount > 2 then
        write( LST_odd, TOF );   {casn't do the else here}
      writeln( LST_odd, TABS, PageCount );
      writeln( LST_odd, TxtLine );
    end;
    LineCount := 2;         {because we printed 2 lines}
  end;
end;

{-- main --}
begin
  if paramcount = 0 then
  begin
    writeln('splits file into odd and even pages for printing');
    writeln('syntax: bookprint <filename>     {using TOF}');
  end
  else

{-- open input file --}
  begin
    filenam := paramstr( 1 );
    assign(InputFile, filenam);
    {$I-}
    reset( InputFile );
    {$I+}
    errcode := IOresult;
    if errcode <> 0 then
      writeln('Error: unable to open input file "', filenam, '"' )
    else

{-- open output files --}
    begin
      assign( LST_odd, filenam + '.odd' );
      rewrite( LST_odd );
      assign( LST_even, filenam + '.even' );
      rewrite( LST_even );
{-- inital printer setup --}
      write( LST_odd, LQ_R_E, MarginOdd );
{-- read write loop --}
      while not EOF( Inputfile ) do
      begin
        readln( Inputfile, TxtLine );
        inc( LineCount );
  {-- long line kludge --}
        if length( TxtLine ) > Maxlen then
        begin
          writeln("WARNING ", length( TxtLine ), " cols at page ", PageCount,
                  ", line ", LineCount );
          inc( LineCount );
        end;
  {-- check for existing TOF --}
        if TxtLine[ 1 ] = TOF then
        begin
          if length( TxtLine ) = 1 then
            TxtLine := ''
          else
            TxtLine[ 1 ] := ' ';
          NewPage;
        end;
  {-- prevent single line at bottem of page --}
        if( LineCount = MaxLines ) and ( length( TxtLine ) = 0 ) then
          NewPage
        else
          if LineCount > MaxLines then
            NewPage
          else
            if IsEven then
              writeln( LST_even, TxtLine )
            else
              writeln( LST_odd, TxtLine );
      end;
{-- adjustment if blank page needed --}
      if IsEven and ( LineCount > AddBlank ) then
      begin
        writeln( LST_odd, TOF );
        writeln("  Added blank page to end");
      end;
      writeln( LST_even, TOF, B_R );
{-- close all files --}
      close( InputFile );
      close( LST_odd );
      close( LST_even );
{-- send to printer --}
      writeln("  Page count = ", PageCount, "; OK to print? [y|n] " );
      repeat
        readln( ch );
      until (ch = "y") or (ch = "n");
      if ch = "y" then
      begin
        {note: if you are using apsfilter, add -Praw after lpr}
        errcode := execute('lpr -r '+ filenam +'.odd');
        writeln("  Now printing odd pages. When finished, reload printer");
        writeln("  to print back of page one and press enter");
        readln;
        errcode := execute('lpr -r '+ filenam +'.even');
      end;
    end;
  end;
end.