path: root/gs/lib/pdfopt.ps

%    Copyright (C) 2000, 2001 Aladdin Enterprises.  All rights reserved.
%
% This software is provided AS-IS with no warranty, either express or
% implied.
%
% This software is distributed under license and may not be copied,
% modified or distributed except as expressly authorized under the terms
% of the license contained in the file LICENSE in this distribution.
%
% For more information about licensing, please refer to
% http://www.ghostscript.com/licensing/. For information on
% commercial licensing, go to http://www.artifex.com/licensing/ or
% contact Artifex Software, Inc., 101 Lucas Valley Road #110,
% San Rafael, CA  94903, U.S.A., +1(415)492-9861.

% $Id$
% PDF linearizer ("optimizer").

.currentglobal true .setglobal
/pdfoptdict 200 dict def
pdfoptdict begin

% This linearizer is designed for simplicity, not for performance.
% See the main program (the last procedure in the file) for comments
% describing the main processing sequence.

% ---------------- Utilities ---------------- %

% ------ Data structures ------ %

% Distinguish dictionaries, arrays, and everything else.
/ifdaelse {		% <obj> <dictproc> <arrayproc> <otherproc> ifdaelse -
  3 index type dup /dicttype eq {
    pop pop pop
  } {
    dup /arraytype ne exch /packedarraytype ne and {
      exch
    } if pop exch pop
  } ifelse exec
} bind def

% Implement dynamically growable arrays using a dictionary.
/darray {		% <size> darray <darray>
  dict
} bind def
/dadd {			% <darray> <value> dadd -
  1 index length exch put
} bind def
/daforall {		% <darray> <proc> daforall -
  /exch cvx /get cvx 3 -1 roll /exec cvx 5 packedarray cvx
  0 1 2 index 0 get length 1 sub 4 -1 roll for
} bind def
/dacontents {		% <darray> dacontents <array>
  [ exch { } daforall ]
} bind def
/dacontstring {		% <darray> dacontstring <string>
  0 1 index { exch pop length add } forall string
  dup /NullEncode filter
                        % Stack: darray str filter
  3 -1 roll { 1 index exch writestring } daforall
  closefile
} bind def

% Force an object, mapping it if it is a reference.
/omforcenew {		% <obj> omforce <obj'> <notseen>
  dup oforce 2 copy eq { pop true } { exch 0 get omapnew exch pop } ifelse
} bind def
/omforce {		% <obj> omforce <obj'>
  omforcenew pop
} bind def
/omget {		% <dict|array> <key> omget <obj>
  get omforce
} bind def
% Visit an entire tree.
/omvisit {		% <obj> omvisit -
  omforcenew {
    { { omvisit omvisit } forall }
    { { omvisit } forall }
    { pop }
    ifdaelse
  } {
    pop
  } ifelse
} bind def
% Visit a tree, stopping at references to Page objects.
% (This is only needed for the OpenAction in the Catalog.)
/omvisitnopage {	% <obj> omvisitnopage -
  dup oforce dup type /dicttype eq {
    /Type .knownget { /Page eq } { false } ifelse
  } {
    pop false
  } ifelse {
    pop		% Page reference
  } {
    omforcenew {
      { { omvisitnopage omvisitnopage } forall }
      { { omvisitnopage } forall }
      { pop }
      ifdaelse
    } {
      pop
    } ifelse
  } ifelse
} bind def

% Collect the list of currently mapped object numbers, in order.
/omapped {		% - omapped <obj#s>
  RMap ld_length larray exch lgrowto
  RMap {
    2 index 3 1 roll 1 sub exch lput
  } ld_forall
} bind def

% Collect the list of object numbers passed to omap by a procedure.
/visited {		% <proc> visited <obj#s>
  false currentomap 2 .execn
  omapped exch setomap
} bind def

% ------ Output ------ %

% Provide a framework for closure-based streams.
.currentglobal false .setglobal
userdict /clostreams 20 dict put	% stream -> [data endproc]
.setglobal
% Create a closure-based stream.
/clostream {		% <data> <proc> <endproc> clostream <stream>
  2 index 3 -1 roll /exec load 3 packedarray cvx
  /NullEncode filter
                % Stack: data endproc stream
  clostreams 1 index 5 -2 roll 2 array astore put
} bind def
% Close a closure-based stream.
/closend {		% <stream> closend <result>
  dup closefile clostreams exch
  2 copy get 3 1 roll undef aload pop exec
} bind def

% Implement in-memory output streams.
/msproc {		% <data> <more> <accum> msproc <scratch>
  3 -1 roll dadd { 100 string } { () } ifelse
} bind def
/mstream {		% - mstream <mstream>
  10 darray {msproc} {dacontstring} clostream
} bind def
/mcontents {		% <mstream> mcontents <string>
  closend
} bind def

% Implement a stream that only keeps track of its position.
% (All streams should do this, but the PLRM doesn't require it.)
/posbuf 100 string def
/posproc {		% <data> <more> <accum> posproc <scratch>
  0 2 copy get 5 -1 roll length add put
  pop //posbuf
} bind def
/postream {		% - postream <postream>
  [0] {posproc} {0 get} clostream
} bind def
/poslength {		% <postream> poslength <pos>
  closend
} bind def

% Implement streams with variable-bit-width data.
% Note that these are dictionary objects, not stream objects.
/bitstream {		% <stream> bitstream <bstream>
  4 dict begin /S exch def /N 8 def /B 0 def
  currentdict end
} bind def
/bitwrite {		% <bstream> <value> <width> bitwrite -
  PDFOPTDEBUG { ( ) print 1 index =only (:) print dup = } if
  3 -1 roll begin
  N exch sub dup 0 ge {
    /N exch def N bitshift B add
  } {
    2 copy bitshift B add S exch write
                        % Stack: value -left
    { 8 add dup 0 ge { exit } if
      2 copy bitshift 255 and S exch write
    } loop
    /N 1 index def bitshift 255 and
  } ifelse /B exch def
  end
} bind def
/bitflush {		% <bstream> bitflush -
  begin N 8 ne { S B write /B 0 def /N 8 def } if end
} bind def

/bwn {                  % <value> <width> bwn -
  2 copy                % v w v w
  2 exch exp ge {       % v w v>=2**w
    /bwn cvx /rangecheck signalerror
  } if
  bits 3 1 roll bitwrite
} def

% Capture OFile output on the temporary file, in memory, or just as a length.
/totemp {		% <proc> totemp <start> <end>
  TFile fileposition OFile
  /OFile TFile def 3 .execn
  /OFile exch def
  TFile fileposition
} bind def
/tomemory {		% <proc> tomemory <string>
  OFile /OFile mstream def 2 .execn
  OFile mcontents exch /OFile exch def
} bind def
/tolength {		% <proc> tolength <string>
  OFile /OFile postream def 2 .execn
  OFile poslength exch /OFile exch def
} bind def

% Copy a range of bytes from TFile to OFile.
/copyrange {		% <start> <end> copybytes -
  TFile 2 index setfileposition
  exch sub 1024 string exch {
                % Stack: buf left
    2 copy 1 index length .min 0 exch getinterval
    TFile exch readstring pop OFile exch writestring
    1 index length sub dup 0 le { exit } if
  } loop pop pop
} bind def

% Pad with blanks to a specified position.
/padto {		% <pos> padto -
  OFile fileposition sub
  dup 0 lt {
    (ERROR: file position incorrect by ) print =
    /padto cvx /rangecheck signalerror
  } {
    { ( ) ows } repeat
  } ifelse
} bind def

% ---------------- Read objects into memory ---------------- %

/touch {		% <object> touch -
  {
    { touch touch } forall
  } {
    dup xcheck {
                % Executable array, must be an indirect object.
      dup 0 get resolved? { pop pop } { oforce touch } ifelse
    } {
      { touch } forall
    } ifelse
  } {
    pop
  } ifdaelse
} bind def

% ---------------- Replace references with referents ---------------- %

/replaceable? {		% <value> replaceable? <bool>
  dup type /integertype eq exch xcheck not and
} bind def
/replacement {		% <obj|ref> replacement <obj'>
  dup oforce dup replaceable? { exch } if pop
} bind def

/replacerefs {		% <object> replacerefs <object>
  {
    dup {
      2 index 2 index undef
      exch replacement exch replacement
      2 index 3 1 roll put
    } forall
  } {
    0 1 2 index length 1 sub {
      1 index exch 2 copy get replacement put
    } for
  } {
  } ifdaelse
} bind def

/replaceReferences {	% - replaceReferences -
  Objects { replacerefs pop } lforall
                % Delete replaced objects.
  0 1 Objects llength 1 sub {
    Objects 1 index lget replaceable? {
      PDFOPTDEBUG { (Deleting ) print dup = } if
      Generations 1 index 0 lput
    } if pop
  } for
} bind def

% ---------------- Create new objects ---------------- %

/createObjects {	% [<obj>...] createObjects <firstobj#>
  Objects llength dup
  dup 3 index length add growPDFobjects
                % Stack: objects objn objn
  3 1 roll exch {
    Objects 2 index 3 -1 roll lput
    Generations 1 index 1 lput
    1 add
  } forall pop
} bind def

% ---------------- Propagate attributes ---------------- %

/nopropattrs <<
        % Never propagate these.
  /Type dup /Kids dup /Count dup /Parent dup
        % Handle Resources specially.
  /Resources dup
>> def

% Merge Resources.
/mergeres {		% <fromdict> <todict> mergeres -
                % Values in todict take priority over fromdict.
  1 index /Resources .knownget {
    1 index /Resources .knownget {
                % Stack: fromdict todict fromres tores
      exch oforce exch oforce
                % todict's Resources may be shared, so make a copy.
      dup length dict .copydict
      exch {
                % Stack: fromdict todict tores' fromkey fromvalue
        2 index 2 index knownoget {
                % Stack: fromdict todict tores' fromkey fromvalue tovalue
          exch oforce exch
                % ProcSet is an array, other types are dictionaries.
          dup type /dicttype eq {
                % Dictionary, not ProcSet.
            exch dup length 2 index length add dict .copydict .copydict
          } {
                % Array or packed array, ProcSet.
                % Use dictionaries to do the merge.
            dup length 2 index length add dict begin
            exch { dup def } forall { dup def } forall
            mark currentdict end { pop } forall .packtomark
          } ifelse
        } if
        2 index 3 1 roll put
      } forall
    } if /Resources exch put pop
  } {
    pop pop
  } ifelse
} bind def

% Merge attributes other than Resources.
/mergeattrs {		% <fromdict> <todict> mergeattrs <fromdict> <todict>
                % Values in todict take priority over fromdict.
  1 index {
                % Stack: fromdict todict fromkey fromvalue
    //nopropattrs 2 index known {
      pop pop
    } {
      2 index 2 index known { pop pop } { 2 index 3 1 roll put } ifelse
    } ifelse
  } forall
} bind def

% Propagate attributes to a subtree.
/proppage {		% <attrs> <subtree> proppage -
                % We should be able to tell when we reach a leaf
                % by finding a Type unequal to /Pages.  Unfortunately,
                % some files distributed by Adobe lack the Type key
                % in some of the Pages nodes!  Instead, we check for Kids.
  dup /Kids knownoget {
                % Accumulate inherited values.
    3 1 roll
                % Stack: kids attrs pagesnode
    dup length dict .copydict mergeattrs
    dup 3 1 roll mergeres
    exch { oforce 1 index exch proppage } forall pop
  } {
                % Merge inherited values into the leaf.
    mergeattrs mergeres
  } ifelse
} bind def

% Propagate attributes to all pages.
/propagateAttributes {	% - propagateAttributes -
  0 dict Trailer /Root oget /Pages oget proppage
} bind def

% ---------------- Identify document-level objects ---------------- %

/identifyDocumentObjects {	% - identifyDocumentObjects <obj#s>
  {
    Trailer /Root omget
    dup /PageMode .knownget { omvisit } if
        % Don't allow omvisit to trace references to Page objects.
    dup /OpenAction .knownget { omvisitnopage } if
    Trailer /Encrypt .knownget { omvisit } if
    dup /Threads .knownget {
        omforce dup //null ne { { omvisitnopage } forall } { pop } ifelse
    } if
    dup /AcroForm .knownget { omvisitnopage } if
    pop
  } visited
} bind def

% ---------------- Identify the objects of each page ---------------- %

/identifyfont {		% <fontref> identifyfont -
  omforce {
    exch /FontDescriptor eq {
      omforce dup /Flags .knownget { 32 and 0 ne } { false } ifelse
      exch {
        exch dup dup /FontFile eq exch /FontFile2 eq or
        exch /FontFile3 eq or 2 index and {
          fontfiles exch dadd
        } {
          omvisit
        } ifelse
      } forall pop
    } {
      omvisit
    } ifelse
  } forall
} bind def

% Collect all the objects referenced from a page.  The first object number
% (which may not be the smallest one) is that of the page object itself.
/identifyPageObjects {	% <extra> <page#> identifyPageObjects <obj#s>
  PDFOPTDEBUG {
    (%Objects for page: ) print dup =
  } if
  pdffindpageref
  dup 0 get 3 1 roll
  4 dict begin
  /filter_params 10 darray def
  /images 10 darray def
  /fontfiles 10 darray def
  {
    omforce
                % Stack: pageobj# extra page
                % Visit any extra objects if applicable.
    exch omvisitnopage
                % Visit Annots, if any.
                % We don't try to defer the drawing information.
    dup /Annots .knownget { omvisitnopage } if
                % Visit beads.
    dup /B .knownget { omvisitnopage } if
                % Visit resources dictionaries.
    dup /Resources .knownget {
      omforce dup {
                % Visit the first-level Resource dictionaries.
        omforce pop pop
      } forall {
                % Visit the resources themselves.
                % Skip Image XObjects, and FontFile streams if the
                % FontDescriptor Flags have bit 6 set.
                % We don't try to visit the resources in the order in which
                % the Contents stream(s) reference(s) them.
        exch dup /XObject eq {
          pop oforce {
            dup oforce /Subtype get /Image eq {
              dup oforce /DecodeParms .knownget {
                oforce {
                  exch /JBIG2Globals eq {
                    filter_params exch dadd
                  } {
                    pop
                  } ifelse
                } forall
              } if
              images exch dadd
            } {
              omvisit
            } ifelse pop
          } forall
        } {
          /Font eq {
            oforce { identifyfont pop } forall
          } {
            oforce omvisit
          } ifelse
        } ifelse
      } forall
    } if
                % Visit the Contents stream(s).
    dup /Contents .knownget { omvisit } if
                % Visit Image XObjects.  We don't try to visit them in
                % reference order.
    filter_params { omvisit } daforall
    images { omvisit } daforall
                % Visit FontFile streams.  We don't try to visit them in
                % reference order.
    fontfiles { omvisit } daforall
    pop
  } visited end
                % Stack: pageobj# obj#s_larray
  [ 3 1 roll {
    2 copy eq { pop } { exch } ifelse
  } lforall counttomark 1 roll ]
  PDFOPTDEBUG {
    (%Objects = ) print dup === flush
  } if
} bind def

% Identify the objects of the first page.
/identifyFirstPageObjects {	% - identifyFirstPageObjects <obj#s>
  Trailer /Root oget null
  1 index /PageMode knownoget {
    /UseOutlines eq {
      1 index /Outlines knownoget { exch pop } if
    } if
  } if exch pop
  1 identifyPageObjects
} bind def

% Identify the non-shared objects of the other pages, and the shared objects.
% Note that the page objects themselves may appear to be shared, because of
% references from Dest entries in annotations, but they must be treated as
% non-shared.  Note also that some objects referenced on the first page may
% also be referenced from other pages.
/identifyOtherPageObjects {	% - identifyOtherPageObjects [<pageobj#s> ...]
                                %   <sharedobj#s>
  4 dict begin
  /marks lstring Objects llength lgrowto def
                % Collect objects of other pages and identify sharing.
  [ 2 1 pdfpagecount { null exch identifyPageObjects } for ]
  dup {
    { marks exch 2 copy lget 1 add 254 .min lput } forall
  } forall
                % Mark document-level and first page objects.
  CatalogNs { marks exch 255 lput } lforall
  FirstPageNs { marks exch 255 lput } forall
                % Mark the page objects themselves as non-shared.
  dup {
    0 get marks exch 1 lput
  } forall
                % Collect the non-shared objects of each page.
  dup
  [ exch {
    [ exch {
      marks 1 index lget 1 ne { pop } if
    } forall ]
  } forall ]
                % Collect the shared objects of each page.
  exch
  [ exch {
    [ exch {
      marks 1 index lget dup 1 le exch 255 eq or { pop } if
    } forall ]
  } forall ]

                % Collect the shared objects.
  [ 1 1 marks llength 1 sub {
    marks 1 index lget dup 1 le exch 255 eq or { pop } if
  } for ]

  end
} bind def

% Identify objects not associated with any page.
/identifyNonPageObjects {	% - identifyNonPageObjects <obj#s>
  4 dict begin
  /marks lstring Objects llength lgrowto def

  LPDictN     marks exch 1 lput
  PHSN        marks exch 1 lput
  CatalogNs   { marks exch 1 lput } lforall
  FirstPageNs { marks exch 1 lput } forall
  SharedNs    { marks exch 1 lput } forall
  OtherPageNs { { marks exch 1 lput } forall } forall

        %****** PUT THESE IN A REASONABLE ORDER ******
  /npobj larray
  0
  1 1 Objects llength 1 sub {
    marks 1 index lget 0 eq {
      Generations exch lget 0 ne { 1 add } if
    } {
      pop
    } ifelse
  } for
  lgrowto def

  0
  1 1 Objects llength 1 sub {
    marks 1 index lget 0 eq {
                                          % i
      Generations 1 index lget 0 ne {
                                          % i
        npobj 2 index                     % i nobj 0
        3 -1 roll                         % nobj 0 i
        lput 1 add
      } {
        pop
      } ifelse
    } {
      pop
    } ifelse
  } for
  pop

  npobj
  end
} bind def

% ---------------- Assign object numbers ---------------- %

% Assign object numbers to all objects that will be copied.
% Return the first (translated) object number in the First Page xref table.
/assignObjectNumbers {		% - assignObjectNumbers -
  OtherPageNs { { omap pop } forall } forall
  SharedNs { omap pop } forall
  NonPageNs { omap pop } lforall
                % Assign object numbers for the First Page xref table last.
  LPDictN omap	% don't pop, this is the return value
  CatalogNs { omap pop } lforall
  FirstPageNs { omap pop } forall
  PHSN omap pop
} bind def

% ---------------- Create the LPDict ---------------- %

% Create the contents of the LPDict.
/createLPDict {			% <phsstart> <phsend> <firstpageend>
                                %   <xref0start> <filelength> createLPDict -
  LPDict
  dup /Linearized 1 put
  dup /L 4 -1 roll put		% filelength
  dup /T 4 -1 roll put		% xref0start
  dup /E 4 -1 roll put		% firstpageend
  dup /H 5 -2 roll 1 index sub 2 array astore put	% phsstart, end-start
  dup /O 1 pdffindpageref 0 get omap put
  /N pdfpagecount put
} bind def

% ---------------- Adjust object positions ---------------- %

/adjustObjectPositions {	% <boundary> <deltabelow> <deltaabove>
                                %   adjustObjectPositions -
        % Objects fall into 4 categories: LPDict, PHS, Catalog, and others.
        % We handle the first two as special cases.
  XRef {
                % Stack: bdy below above key loc
    dup 5 index ge { 2 } { 3 } ifelse index add
    XRef 3 1 roll ld_put
  } ld_forall pop pop pop
  XRef LPDictN omap HeaderLength ld_put
  XRef PHSN omap PHSStart ld_put
} bind def

% ---------------- Write the output file ---------------- %

% Write objects identified by object number.
/writeobjn {		% <obj#> writeobjn -
  Generations 1 index lget pdfwriteobj
} bind def
/writeobjns {		% <obj#s> writeobjns -
  { writeobjn } forall
} bind def
/lwriteobjns {		% <obj#s> writeobjns -
  { writeobjn } lforall
} bind def

% Write a part of the output file.
/writePart {		% <proc> <label> writePart -
  PDFOPTDEBUG {
    dup print ( count=) print count =only ( start=) print
    OFile { .fileposition } stopped { pop (???) } if =
    2 .execn
    print ( end=) print
    OFile { .fileposition } stopped { pop (???) } if =
  } {
    pop exec
  } ifelse
} bind def

% Write the header.
/writePart1 {		% - writePart1 -
  {
    pdfwriteheader
  } (part1) writePart
} bind def

% Write the linearization parameters dictionary.
/writePart2 {		% - writePart2 -
  {
    LPDictN writeobjn
  } (part2) writePart
} bind def

% Write the First Page xref table and trailer.
% Free variables: FirstPageXN.
/writePart3 {		% <xrefstart> writePart3 -
  {
    FirstPageXN NObjects 1 add 1 index sub pdfwritexref
    Trailer dup length 1 add dict copy Trailer xcheck { cvx } if
    dup /Size NObjects 1 add put
    dup /Prev 4 -1 roll put
    pdfwritetrailer
    0 pdfwritestartxref
  } (part3) writePart
} bind def

% Write the Catalog and other required document-level objects.
% Free variables: CatalogNs.
/writePart4 {		% - writePart4 -
  {
    CatalogNs lwriteobjns
  } (part4) writePart
} bind def

% Write the Primary Hint Stream.
/writePart5 {		% - writePart5 -
  {
    PHSN writeobjn
  } (part5) writePart
} bind def

% Write the First Page's objects.
% Free variables: FirstPageNs.
/writePart6 {		% - writePart6 -
  {
    FirstPageNs writeobjns
  } (part6) writePart
} bind def

% Write the objects of other pages (Page + non-shared objects).
% Free variables: OtherPageNs.
/writePart7 {		% - writePart7 <lengths>
  {
    [ OtherPageNs {
      OFile fileposition exch
      writeobjns OFile fileposition exch sub
    } forall ]
  } (part7) writePart
} bind def

% Write the shared objects of other pages.
% Free variables: SharedNs.
/writePart8 {		% - writePart8 -
  {
    SharedNs writeobjns
  } (part8) writePart
} bind def

% Write the other objects not associated with pages.
% Free variables: NonPageNs.
/writePart9 {		% - writePart9 -
  {
    NonPageNs { writeobjn } lforall
  } (part9) writePart
} bind def

% Write the main xref table and trailer.
% Free variables: FirstPageXN.
/writePart11xref {	% writePart11 -
  {
    0 FirstPageXN pdfwritexref
  } (part11xref) writePart
} bind def
/writePart11rest {	% <part3start> writePart11rest -
  {
    << /Size FirstPageXN >> pdfwritetrailer
    pdfwritestartxref
  } (part11rest) writePart
} bind def

% ---------------- Write hint tables ---------------- %

/bitsneeded {		% <maxvalue> bitsneeded <#bits>
  0 exch { dup 0 eq { pop exit } if exch 1 add exch 2 idiv } loop
} bind def

% Find the start and end of objects in the output.
/omstart {		% <obj#> omstart <pos>
  PDFOPTDEBUG { (start\() print dup =only } if
  omap
  PDFOPTDEBUG { (=>) print dup =only } if
  XRef exch ld_get
  PDFOPTDEBUG { (\) = ) print dup = } if
} bind def
/omend {		% <obj#> omend <pos>
        % The end of an object is the start of the next object.
        % The caller must be sure that this object is not the last one
        % in part 9.
  PDFOPTDEBUG { (end\() print dup =only } if
  omap
  PDFOPTDEBUG { (=>) print dup =only } if
  1 add
        % Check that the requested object wasn't the last one in part 6:
        % the next object in the output file is the first in part 7.
  PHSN omap 1 index eq { pop 1 } if
  XRef exch ld_get
  PDFOPTDEBUG { (\) = ) print dup = } if
} bind def
/omlength {		% <obj#> omlength <length>
  dup omend exch omstart sub
} bind def

% Find the Contents of a page.
/contentsobjects { % <pagedict> contentsobjects <firstobj#> <lastobj#> true
                   % <pagedict> contentsobjects false
  /Contents .knownget {
    dup oforce                   % ref []
    dup type /dicttype eq {
      pop 0 get dup true         % ref ref
    } {
      exch pop                   % []
      dup length 0 ne {
        dup 0 get 0 get          % [] 1st
        exch dup                 % 1st [] []
        length 1 sub get 0 get   % 1st last
        true
      } {
        pop false
      } ifelse
    } ifelse
  } {
    false
  } ifelse
} bind def

/contentsstart {	% <pagedict> contentsstart <pos> true
                        % <pagedict> contentsstart false
  contentsobjects { pop omstart true } { false } ifelse
} bind def

/contentslength {	% <pagedict> contentslength <length>
  contentsobjects { omend exch omstart sub } { 0 } ifelse
} bind def

/writePageOffsetHints {
  PDFOPTDEBUG { /writePageOffsetHints == } if
  20 dict begin
  /bits OFile bitstream def

        % Calculate least length of a page.
  FirstPageLength OtherPageLengths { .min } forall
  /minpl exch def

        % Calculate least contents length.
  FirstPageNs 0 get Objects exch lget contentslength
  OtherPageNs { 0 get Objects exch lget contentslength .min } forall
  /mincl exch def

        % The Adobe documentation says that all versions of Acrobat
        % require item 8 (mincl) to be zero.  Patch this here.
  /mincl 0 def

        % Calculate bits needed to represent greatest page length.
  FirstPageLength OtherPageLengths { .max } forall
  minpl sub bitsneeded /maxplbits exch def
        % Calculate bits needed to represent the greatest Contents length.
  FirstPageNs 0 get Objects exch lget contentslength
  OtherPageNs { 0 get Objects exch lget contentslength .max } forall
  mincl sub bitsneeded /maxclbits exch def

        % Per Adobe documentation, Acrobat requires that item 5 (maxplbits)
        % be equal to item 9 (maxclbits).  Set both to the max of the two.
  maxplbits maxclbits .max /maxplbits 1 index def /maxclbits exch def

        % Mapping from object number to shared object reference
  /shared_id_dict FirstPageNs length SharedNs length add dict begin
  0 FirstPageNs { 1 index def 1 add } forall
    SharedNs { 1 index def 1 add } forall
  pop
  currentdict end def

                % Table F.3 Page offset hint table, header section

                % 1: Least number of objects in a page:
  FirstPageNs length OtherPageNs { length .min } forall
  /minnop 1 index def 32 bwn
                % 2: Location of first page's Page object:
  FirstPageNs 0 get omap XRef exch ld_get 32 bwn
                % 3: Bits needed to represent greatest # of objects in a page:
  FirstPageNs length OtherPageNs { length .max } forall
  minnop sub bitsneeded /maxnopbits 1 index def 16 bwn
                % 4: Least length of a page:
  minpl 32 bwn
                % 5: Bits needed to represent the greatest page length:
  maxplbits 16 bwn
                % 6: Least start of Contents offset:
  0		% (Acrobat requires that this be 0.)
  /minsco 1 index def 32 bwn
                % 7: Bits needed to represent the greatest start of Contents
                % offset:
  0		% (Acrobat ignores this.)
  /maxscobits 1 index def 16 bwn
                % 8: Least contents length:
  mincl 32 bwn
                % 9: Bits needed to represent the greatest Contents length:
  maxclbits 16 bwn
                % 10: Bits needed to represent the greatest number of Shared
                % Object references:
  FirstPageNs length SharedPageNs { length .max } forall bitsneeded
  /maxsorbits 1 index def 16 bwn
                % 11: Bits needed to identify a Shared Object:
  FirstPageNs length SharedNs length add bitsneeded
  /sobits 1 index def 16 bwn
                % 12: Bits needed to represent numerator of fraction:
  2
  /numfbits 1 index def 16 bwn
                % 13: Denominator of fraction:
  1
  /denf 1 index def 16 bwn

                % Table F.4 Page offset hint table, per-page entry

                % 1: Number of objects in pages:
  FirstPageNs length minnop sub maxnopbits bwn
  OtherPageNs {
    length minnop sub maxnopbits bwn
  } forall
  bits bitflush

                % 2: Total length of pages in bytes;
  FirstPageLength minpl sub maxplbits bwn
  OtherPageLengths {
    minpl sub maxplbits bwn
  } forall
  bits bitflush

                % 3: Number of shared objects referenced from page:
  FirstPageNs length maxsorbits bwn
  SharedPageNs { length maxsorbits bwn } forall
  bits bitflush
                % 4: A shared object identifier:
  FirstPageNs { shared_id_dict exch get sobits bwn } forall
  SharedPageNs {
    { shared_id_dict exch get sobits bwn
    } forall
  } forall
  bits bitflush

                % 5: Numerator of fractional position for each shared object:
  FirstPageNs { pop 0 numfbits bwn  } forall
  SharedPageNs {
    { pop 0 numfbits bwn
    } forall
  } forall
  bits bitflush

                % 6: Contents offsets:
                % Following Implementation Note 133 section 6 is empty.
  maxscobits 0 gt {
    [FirstPageNs OtherPageNs aload pop] {
       0 get Objects exch lget contentsstart { minsco sub } { 0 } ifelse
       maxscobits bwn
    } forall
    bits bitflush
  } if

                % 7: Contents lengths:
  [FirstPageNs OtherPageNs aload pop] {
    0 get Objects exch lget contentslength mincl sub maxclbits bwn
  } forall
  bits bitflush

  end

} bind def

/writeSharedObjectHints {
  PDFOPTDEBUG { /writeSharedObjectHints == } if
  20 dict begin
  /bits OFile bitstream def
  /obj_count SharedNs length FirstPageNs length add def

                % Table F.5 Shared object hint table, header section

                % 1: Object number of first object in Shared Objects section
  0 32 bwn
                % 2: Location of first object in Shared Objects section:
                % If there are no shared objects,
                % Acrobat sets this to the location of linearization
                % parameters object (the very first object).
  { pdfwriteheader } tomemory length 32 bwn
                % 3: Number of Shared Object entries for first page:
  FirstPageNs length 32 bwn
                % 4: Number of Shared Object entries for Shared Objects
                % section
  obj_count 32 bwn
                % 5: Bits needed to represent the greatest number of objects
                % in a shared object group (always 0, because all groups
                % have only 1 object):
  0 16 bwn
                % 6: Least length of a Shared Object Group in bytes:
  16#7fffffff FirstPageNs { omlength .min } forall
                 SharedNs { omlength .min } forall
  /minsol 1 index def 32 bwn
                % 7: Bits needed to represent the greatest length of a
                % Shared Object Group:
  0 FirstPageNs { omlength .max } forall
       SharedNs { omlength .max } forall
  minsol sub bitsneeded
  /maxsolbits 1 index def 16 bwn

                % Table F.6 Shared object hint table, shared object group entry

                % 1: Lengths of shared object groups:
  FirstPageNs { omlength minsol sub maxsolbits bwn } forall
     SharedNs { omlength minsol sub maxsolbits bwn } forall
  bits bitflush
                % 2: MD5 flag:
  obj_count { 0 1 bwn } repeat
  bits bitflush
                % 3: No MD5 shared object signatures.

                % 4: No number_number_of_objects_in_the_group - 1
  end
} bind def

% ---------------- Main program ---------------- %

/pdfOptimize {		% <infile> <outfile> pdfOptimize -
  realtime 3 1 roll
  exch pdfdict begin pdfopenfile dup begin
  40 dict begin
  /IDict exch def
  /OFile exch def
  /starttime exch def
  /ToWrite 100 dict def
  /now {
    QUIET { pop } { print (, t = ) print realtime starttime sub = flush } ifelse
  } def
  omapinit

        % Create and open a temporary file.
        % Because of .setsafe, we have to open it as read-write, rather than
        % opening for writing, then closing it and reopening it for reading.

  null (w+) .tempfile /TFile exch def /TFileName exch def
  .setsafe

        % Read all objects into memory.

  Trailer touch
  (Read objects) now

        % Encrypted files are not yet supported.
  Trailer /Encrypt known {
    (ERROR: Encrypted files are not yet supported.) = flush
    /pdfOptimize cvx /limitcheck signalerror
  } if

        % Replace indirect references to numbers.  This is needed
        % for the Length of streams, and doesn't hurt anything else.

  replaceReferences
  (Replaced references) now

        % Create the two new objects: the linearization parameter
        % dictionary, and the Primary Hint Stream.

  /LPDict 10 dict def
  /PHS 10 dict cvx def		% executable = stream
  [LPDict PHS] createObjects
  /LPDictN 1 index def 1 add
  /PHSN exch def
  PDFOPTDEBUG { << /LPDictN LPDictN /PHSN PHSN >> === } if

        % Count the number of objects in the output.

  0 0 1 Objects llength 1 sub {
    Generations exch lget 0 ne { 1 add } if
  } for
  /NObjects exch def
  QUIET not { NObjects =only ( objects total) = flush } if

        % Propagate inherited attributes down the page tree.

  propagateAttributes
  (Propagated attributes) now

        % Identify the document-level objects (part 4).

  identifyDocumentObjects /CatalogNs exch def
  QUIET not { CatalogNs === flush } if
  (Identified Catalog) now

        % Identify the first page's objects (part 6),
        % including the Outlines tree if appropriate.

  pdfopencache
  /FirstPageNs identifyFirstPageObjects def
  QUIET not { FirstPageNs === flush } if
  (Identified first page) now

        % Identify shared vs. non-shared objects for remaining pages
        % (parts 7 and 8).

  identifyOtherPageObjects
  /SharedNs exch def
  /SharedPageNs exch def
  /OtherPageNs exch def
  QUIET not { OtherPageNs === flush SharedNs === flush } if
  (Identified other pages) now

        % Identify objects not associated with any page (part 9).

  /NonPageNs identifyNonPageObjects def
  QUIET not { NonPageNs { === } forall flush } if
  (Identified non-pages) now

        % Assign final object numbers to all the objects.
        % (The omap is currently empty.)

  /FirstPageXN assignObjectNumbers def
  (Assigned objects #s) now

        % Write the document-level objects (part 4).

  { writePart4 } totemp
  /CatalogTempEnd exch def /CatalogTempStart exch def
  (Wrote Catalog) now

        % Write the first page's objects (part 6).

  { writePart6 } totemp
  /FirstPageTempEnd exch def /FirstPageTempStart exch def
  (Wrote first page) now

        % Write the non-shared objects for other pages (part 7).

  { writePart7 /OtherPageLengths exch def } totemp
  /OtherPageTempEnd exch def /OtherPageTempStart exch def
  (Wrote other pages) now

        % Write the shared objects for other pages (part 8).

  { writePart8 } totemp
  /SharedTempEnd exch def /SharedTempStart exch def
  (Wrote shared objects) now

        % Write the objects not associated with pages (part 9).

  { writePart9 } totemp
  /NonPageTempEnd exch def /NonPageTempStart exch def

        % Compute conservative lengths of parts 2,3,5,11 of the output.
        % It's OK for these to be too large, but not too small.

  % Make dummy XRef entres for LPDict and PHS.
  XRef LPDictN omap 0 ld_put
  XRef PHSN omap 0 ld_put

  /HeaderLength {	% this is exact
    writePart1			% part 1
  } tolength def
  /CatalogLength	% this is exact
    CatalogTempEnd CatalogTempStart sub def	% part 4
  /FirstPageLength	% this is exact
    FirstPageTempEnd FirstPageTempStart sub def	% part 6
  /OtherObjectsLength	% this is exact
    NonPageTempEnd OtherPageTempStart sub def	% parts 7,8,9
  /ObjectsLength	% this is exact
    CatalogLength FirstPageLength add OtherObjectsLength add def
  /XrefLength {			% part 11
        % The LPDict must end within the first 1024 bytes,
        % so the start of the FirstPage xref table can't exceed 1024.
    writePart11xref 1024 writePart11rest
  } tolength def
  /NominalFileLength 	% Make a generous allowance for parts 2,3,5.
    HeaderLength ObjectsLength 3 mul add 10000 add 99999 .max def
  /FirstPageXrefLength {	% part 3
    NominalFileLength writePart3
  } tolength def
  /LPDictLength {		% part 2
    NominalFileLength dup 2 mul 2 copy add 1 index dup createLPDict writePart2
  } tolength def

        % Compute a few additional values from the above.

  /XrefBeginLength {
    (xref\n0 ) ows
    OFile FirstPageXN write=
  } tolength def
  HeaderLength LPDictLength add
  /FirstPageXrefStart 1 index def
  FirstPageXrefLength add
  /CatalogStart 1 index def
  CatalogLength add		% phsstart
  /PHSStart exch def

        % Adjust the object positions ignoring PHS.
        % (Writing the PHS needs these.)

  0 0 CatalogStart CatalogTempStart sub adjustObjectPositions
  % Make a temporary XRef entry for the PHS, for the benefit of omend.
  XRef PHSN omap CatalogStart ld_put
  (Adjusted positions) now

        % Construct the hint tables (part 5).

  { writePageOffsetHints } totemp
  pop /PHSTempStart exch def
  { writeSharedObjectHints } totemp
  exch PHSTempStart sub PHS /S 3 -1 roll put
  PHSTempStart sub /PHSTempLength exch def
  (Wrote hints) now

  % Prepare to read TFile.
%  TFile closefile
%  /TFile TFileName (r) file def

  PHS
    dup /File TFile put
    dup /FilePosition PHSTempStart put
    dup /Length PHSTempLength put
  pop
  /PHSLength { writePart5 } tolength def

        % Construct the linearization parameter dictionary (part 2).

  PHSStart
  dup PHSLength add		% phsend
  /FirstPageStart 1 index def
  dup FirstPageLength add	% firstpageend
  dup OtherObjectsLength add
  /XrefStart 1 index def
  XrefBeginLength add		% xref0start
  dup XrefBeginLength sub XrefLength add	% fileend
        % Because of a bug, Acrobat Reader doesn't recognize any file
        % shorter than 1K as linearized.  Patch this here.
      % Acrobat 9 insists on 4KB
  4096 .max
  /FileLength 1 index def
  createLPDict

        % Adjust the object positions again, taking the PHS into account.

  PHSStart 0 PHSLength adjustObjectPositions
  (Readjusted positions) now

        % Finally, write the output file.

  writePart1
  writePart2
  FirstPageXrefStart padto
  XrefStart writePart3
  CatalogStart padto
  CatalogTempStart CatalogTempEnd copyrange	% part 4
  writePart5
  FirstPageStart padto
  FirstPageTempStart NonPageTempEnd copyrange	% parts 6,7,8,9
  % No Overflow Hint Stream (part 10).
  XrefStart padto
  writePart11xref
  { FirstPageXrefStart writePart11rest } tomemory
  FileLength 1 index length sub padto ows
  (Wrote output file) now

        % Wrap up.

  TFile closefile TFileName deletefile
  end		% temporary dict
  end		% IDict
} bind def

end			% pdfoptdict
.setglobal

% Check for command line arguments.
[ shellarguments {
  ] dup length 2 eq {
        % Load the pdfwrite utilities if necessary.
    /omapinit where { pop } { (pdfwrite.ps) runlibfile } ifelse
    save exch
    aload pop exch (r) file exch (w) file
    3000000 setvmthreshold
    0 setobjectformat
    pdfoptdict begin pdfOptimize end
    restore
  } {
    (Usage: gs -dNODISPLAY -- pdfopt.ps input.pdf output.pdf) = flush quit
  } ifelse
} {
  pop
} ifelse