% Copyright (C) 2001-2023 Artifex Software, Inc.
% 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.
%
% Refer to licensing information at http://www.artifex.com or contact
% Artifex Software, Inc.,  39 Mesa Street, Suite 108A, San Francisco,
% CA 94129, USA, for further information.
%

% The current implementation of setpagedevice has the following limitations:
%	- It doesn't attempt to "interact with the user" for Policy = 2.

languagelevel 1 .setlanguagelevel
level2dict begin
% ---------------- Redefinitions ---------------- %

% Define interpreter callouts for handling gstate-saving operators,
% to make sure that they create a page device dictionary for use by
% the corresponding gstate-restoring operator.
% We'd really like to avoid the cost of doing this, but we don't see how.
% The names %gsavepagedevice, %savepagedevice, %gstatepagedevice,
% %copygstatepagedevice, and %currentgstatepagedevice are known to the
% interpreter.

(%gsavepagedevice) cvn
 { currentpagedevice pop gsave
 } bind def

(%savepagedevice) cvn
 { currentpagedevice pop save
 } bind def

(%gstatepagedevice) cvn
 { currentpagedevice pop gstate
 } bind def

(%copygstatepagedevice) cvn
 { currentpagedevice pop copy
 } bind def

(%currentgstatepagedevice) cvn
 { currentpagedevice pop currentgstate
 } bind def

% Define interpreter callouts for handling gstate-restoring operators
% when the current page device needs to be changed.
% The names %grestorepagedevice, %grestoreallpagedevice,
% %restorepagedevice, %restore1pagedevice, and %setgstatepagedevice
% are known to the interpreter.

% ---------------- Keys and Attributes ---------------- %

% We have to deal specially with entries that the driver may change
% on its own. We also have to deal specially with parameters which the device may
% change on its own but which we *also* want to transmit to the device. Previously
% any parameter which was 'dynamic' would not be sent to the device, making it
% impossible to set a parameter, and later have the device change it. Currently
% only OutputICCProfile fits this category.
% This whole area is broken its completely the wrong way round from the way the spec says it should work.

% This dictionary contains the keys we never want to set.
/.readonlypdkeys mark
  /.MediaSize dup		% because it changes when PageSize is set
  /PageCount dup
  /Colors dup
  /BitsPerPixel dup
  /ColorValues dup
.dicttomark readonly def

% Bonkers, but needed by our ridiculous setpagedevice implementation. There are
% some keys (at the moment, RedValues, GreenValues and BlueValues are known) which
% only exist in the page device dictionary under some conditions (ProcessColorModel == DeviceRGB)
% If we change the conditions, so that these keys are no longer present in the params
% returned by the device, sending these keys to the device can trigger a fault.
% This is a problem because of our stored dictionary:
%
% 1) Set up the inital dictioanry by retrieving the params from the device
% 2) Change the conditions (ProcessColorModel == DeviceGray)
% 3) merge any volatile keys from the device. Note that RedValues etc no longer defined.
% 4) Call .installpagdevice, use the stored dicitonary to set the params
% 5) The stored RedValues etc, cause an error.
%
% The stored dictioanry is readonly (we use forceput to wedge new keys into it) so
% we can't 'undef' keys from it. (the dictionary is made readonly by the action of zsetpagedevice
% '.setpagedevice' in PostScrfipt)
%
% So the only solution is to have 'write only' keys. These can be written to the device
% but are not stored in the saved page device dictionary. This means PostScript programs
% can't interrogate and take action on these, but there's no solution to that except to
% rewrite this stuff completely so that it actually works properly.

/.writeonlykeys mark
  /RedValues dup        % Set by the device when ProcessColorModel changes
  /GreenValues dup      % Set by the device when ProcessColorModel changes
  /BlueValues dup       % Set by the device when ProcessColorModel changes
  /GrayValues dup       % Set by the device when ProcessColorModel changes
.dicttomark readonly def

% This dictionary contains the keys we always want to read back from the device.
/.volatilepdkeys mark
  /.MediaSize dup		% because it changes when PageSize is set
  /RedValues dup        % Set by the device when ProcessColorModel changes
  /GreenValues dup      % Set by the device when ProcessColorModel changes
  /BlueValues dup       % Set by the device when ProcessColorModel changes
  /GrayValues dup       % Set by the device when ProcessColorModel changes
  /PageCount dup
  /Colors dup
  /BitsPerPixel dup
  /ColorValues dup
  /OutputICCProfile dup		% ColorConversionStrategy can change this
.dicttomark readonly def

% The implementation of setpagedevice is quite complex.  Currently,
% everything but the media matching algorithm is implemented here.

% By default, we only present the requested changes to the device,
% but there are some parameters that require special merging action.
% Define those parameters here, with the procedures that do the merging.
% The procedures are called as follows:
%	<merged> <key> <new_value> -proc- <merged> <key> <new_value'>
/.mergespecial mark
  /InputAttributes
   { dup //null eq
      { pop //null
      }
      { 3 copy pop .knownget
         { dup //null eq
            { pop dup length dict }
            { dup length 2 index length add dict .copydict }
           ifelse
         }
         { dup length dict
         }
        ifelse .copydict readonly
      }
     ifelse
   } bind
  /OutputAttributes 1 index
  /Policies
    { 3 copy pop .knownget
       { dup length 2 index length add dict .copydict }
       { dup length dict }
      ifelse copy readonly
    } bind
.dicttomark readonly def

% M. Sweet, Easy Software Products:
%
% Define NOMEDIAATTRS to turn off the default (but unimplementable) media
% selection policies for setpagedevice.  This is used by CUPS to support
% the standard Adobe media attributes.
NOMEDIAATTRS {
  % Define only PageSize for input attribute matching.
  /.inputattrkeys [
    /PageSize
  ] readonly def
  % Define no other keys used in media selection.
  /.inputselectionkeys [
    /noInputSelectionsKeys
  ] readonly def

  % Define no keys used in output attribute matching.
  /.outputattrkeys [
    /noOutputAttrKeys
  ] readonly def
} {
  % Define the keys used in input attribute matching.
  /.inputattrkeys [
    /PageSize /MediaColor /MediaWeight /MediaType /InsertSheet /ManualFeed
          % The following are documented in Adobe's supplement for v2017.
    /LeadingEdge /MediaClass
  ] readonly def
  % Define other keys used in media selection.
  /.inputselectionkeys [
    /MediaPosition /Orientation
  ] readonly def

  % Define the keys used in output attribute matching.
  /.outputattrkeys [
    /OutputType
  ] readonly def
} ifelse

% Define all the parameters that should always be copied to the merged
% dictionary.
/.copiedkeys [
  /OutputDevice
  //.mergespecial { pop } forall
  .inputattrkeys aload pop
  .inputselectionkeys aload pop
  .outputattrkeys aload pop
] readonly def

% Define the parameters that should not be presented to the device.
% The procedures are called as follows:
%	<merged> <key> <value> -proc-
% The procedure leaves all its operands on the stack and returns
% true iff the key/value pair should be presented to .putdeviceparams.
/.presentspecial mark
  .readonlypdkeys
      { pop //false }
  forall
                        % We must ignore an explicit request for .MediaSize,
                        % because media matching always handles this.
  /.MediaSize //false
  /Name //false
  /OutputDevice //false
  /PageDeviceName //false
  /PageOffset //false
  /PageSize //false		% obsolete alias for .MediaSize
  /InputAttributes //false
  .inputattrkeys
       { dup dup /PageSize eq exch /LeadingEdge eq or
       { pop }
       { { 2 index /InputAttributes .knownget { //null eq } { //true } ifelse } }
      ifelse
    }
  forall
  .inputselectionkeys { //false } forall
  /OutputAttributes //false
  .outputattrkeys
    { { 2 index /OutputAttributes .knownget { //null eq } { //true } ifelse } }
  forall
  /Install //false
  /BeginPage //false
  /EndPage //false
  /Policies //false
        % Our extensions:
  /HWColorMap
    {			% HACK: don't transmit the color map, because
                        % window systems can change the color map on their own
                        % incrementally.  Someday we'll have a better
                        % solution for this....
      //false
    }
  /ViewerPreProcess //false
  /ImagingBBox //false	% This prevents the ImagingBBox value in the setpagedevice
                        % from affecting the device's ImagingBBox parameter, but
                        % does retain a 'shadow' copy at the PostScript level.
                        % This is done for Adobe compatibility since Adobe does
                        % render marks outside the ImagingBBox (and QuarkXpress
                        % relies on it).
.dicttomark readonly def

% ---------------- End Keys and Attributes ---------------- %

% Prepare to present parameters to the device, by spreading them onto the
% operand stack and removing any that shouldn't be presented.
/.prepareparams		% <params> .prepareparams -mark- <key1> <value1> ...
 { mark exch dup
    {			% Stack: -mark- key1 value1 ... merged key value
      //.presentspecial 2 index .knownget
       { exec { 3 -1 roll } { pop pop } ifelse }
       { 3 -1 roll }
      ifelse
    }
   forall pop
 } bind def

currentdict /.presentspecial .undef

% Compute the media size and initial matrix from a merged request (after
% media selection).
/.computemediasize	% <request> .computemediasize
                        %   <request> <matrix> <[width height]>
 { dup /PageSize get					% requested page size
   1 index /InputAttributes get
     2 index (%MediaSource) get get /PageSize get	% media size
                                                        % (may be a range)
   2 index /Policies get
     dup /PageSize .knownget
      { exch pop } { /PolicyNotFound get } ifelse	% PageSize policy,
                                                        % affects scaling
   3 index /Orientation .knownget not { //null } if
   4 index /RollFedMedia .knownget not { //false } if
   matrix .matchpagesize not {
                % This is a "can't happen" condition!
     /setpagedevice .systemvar /rangecheck signalerror
   } if
   2 array astore
 } bind def

% Try setting the device parameters from the merged request.
/.trysetparams		% <merged> <(ignored)> <device> <Policies>
                        %   .trysetparams
 { //true 4 index //.prepareparams exec
                        % Add the computed .MediaSize.
                        % Stack: merged (ignored) device Policies -true-
                        %   -mark- key1 value1 ...
   counttomark 5 add index //.computemediasize exec
   exch pop exch pop /.MediaSize exch
SETPDDEBUG { (Putting.) = pstack flush } if
   .putdeviceparamsonly
SETPDDEBUG { (Result of putting.) = pstack flush } if
 } bind executeonly odef

/.installpagedevice
 {	% Since setpagedevice doesn't create new device objects,
        % we must (carefully) reinstall the old parameters in
        % the same device.
   .currentpagedevice pop //null currentdevice //null
   { //.trysetparams } //.internalstopped exec
   {
     //null
   } if
   dup type /booleantype eq
    { pop pop }
    {
      SETPDDEBUG { (Error in .trysetparams!) = pstack flush } if
      {cleartomark pop pop pop} //.internalstopped exec pop
      % if resetting the entire device state failed, at least put back the
      % security related key
      currentdevice //null //false mark /.LockSafetyParams
      currentpagedevice /.LockSafetyParams .knownget not
      {systemdict /SAFER .knownget not {//false} } if
      .putdeviceparamsonly
      /.installpagedevice cvx /rangecheck signalerror
    }
   ifelse pop pop
        % A careful reading of the Red Book reveals that an erasepage
        % should occur, but *not* an initgraphics.
   erasepage .beginpage
 } bind executeonly def

/.uninstallpagedevice
 {
   {2 .endpage { .currentnumcopies //false .outputpage } if} //.internalstopped exec pop
   nulldevice
 } bind executeonly def

(%grestorepagedevice) cvn
 {
 .uninstallpagedevice
 grestore
 //.installpagedevice exec
 } bind def

(%grestoreallpagedevice) cvn
 { .uninstallpagedevice grestore //.installpagedevice exec grestoreall
 } bind def

(%restore1pagedevice) cvn
 { .uninstallpagedevice grestore //.installpagedevice exec restore
 } bind def

(%restorepagedevice) cvn
 { .uninstallpagedevice restore //.installpagedevice exec
 } bind def

(%setgstatepagedevice) cvn
 { .uninstallpagedevice setgstate //.installpagedevice exec
 } bind def

% Redefine .currentpagedevice and .setpagedevice so they convert between
% null and a fixed empty directionary.
/.nullpagedevice 0 dict readonly def
/.currentpagedevice {
  //.currentpagedevice exch dup //null eq { pop //.nullpagedevice } if exch
} bind odef
/.setpagedevice {
  dup //.nullpagedevice eq { pop //null } if //.setpagedevice
} bind odef

% ---------------- Auxiliary definitions ---------------- %

% Define the required attributes of all page devices, and their default values.
% We don't include attributes such as .MediaSize, which all devices
% are guaranteed to supply on their own.
/.defaultpolicies mark
  % M. Sweet, Easy Software Products
  %
  % Due to the fact that it is not possible to properly implement
  % the selection policies from a Ghostscript driver, we have changed
  % the default policy to "7" (impose) to avoid numerous problems with
  % printing within CUPS...
  %
  % If NOMEDIAATTRS is false, the set the default depending on whether
  % PSFitPage is true. Policy 13 does best fit with page scaling up or down
  % so it is only useful if FIXEDMEDIA is also specified, or if the set of
  % media in the InputAttributes dictionary is the actual available choices
  % and does not include any "range" page sizes.
  /PageSize NOMEDIAATTRS { 7 } { //systemdict /PSFitPage known { 13 } { 0 } ifelse } ifelse
  /PolicyNotFound 1
  /PolicyReport {
    dup /.LockSafetyParams known {
        % Only possible error is invalidaccess
      /setpagedevice .systemvar /invalidaccess signalerror
    }
    if
    pop
  } bind
.dicttomark readonly def
% Note that the values of .requiredattrs are executed, not just fetched.
/.requiredattrs mark
  /PageDeviceName //null
  /PageOffset [0 0] readonly
% We populate InputAttributes with all of the known page sizes
% followed by a dummy media type that handles pages of any size.
% This will create some duplicates, but that only slightly slows
% down the media selection (loop is in zmedia2.c).
%
% Some PostScript creators assume that slot 0 is the default media
% size and some can't handle a non-standard 4-element array which
% is a 'range' type page size (always put last).
%
% Real Devices that can only handle specific page sizes will override this.
  /InputAttributes {
    mark
    % First put the device's default page size in slot 0
    % This satifies those that have devices built with a4 as the default
    0 mark /PageSize /GetDeviceParam .special_op
    not {/setpagedevice .systemvar /configurationerror signalerror} if .dicttomark
    % Only populate the other entries if we aren't FIXEDMEDIA
    FIXEDMEDIA not {
      statusdict /.pagetypenames get {
        statusdict /.pagetypeprocs get
        exch get 0 2 getinterval cvlit
        counttomark 1 sub 2 idiv exch mark exch /PageSize exch
        % stack: mark --dict-- --dict-- ... key mark /PageSize [x y]
        % see note above about pagetype executable array contents.
        .dicttomark
      } forall
      % If NORANGEPAGESIZE is defined, (-dNORANGEPAGESIZE), then don't add
      % the 'match any' PageSize entry
      systemdict /NORANGEPAGESIZE known not {
        % Add one last entry which is the 4 element range array (non-standard)
        counttomark 2 idiv
          % PageSize with either dimension 0 will be detected in
          % match_page_size, so we can allow it here
        mark /PageSize [0 dup 16#7ffff dup] .dicttomark
      } if
    } if % FIXEDMEDIA false
    .dicttomark
  }
  (%MediaSource) 0
  /OutputAttributes {
    mark 0 mark .dicttomark readonly .dicttomark
  }
  (%MediaDestination) 0
  /Install {{.callinstall}} bind
  /BeginPage {{.callbeginpage}} bind
  /EndPage {{.callendpage}} bind
  /Policies .defaultpolicies
  /ImagingBBox //null		% default value
  /UseCIEColor /.getuseciecolor load
.dicttomark readonly def

% Define currentpagedevice so it creates the dictionary on demand if needed,
% adding all the required entries defined just above.

/.makecurrentpagedevice {	% - .makecurrentpagedevice <dict>
  currentdevice //null .getdeviceparams
        % Make the dictionary large enough to add defaulted entries.
  counttomark 2 idiv //.requiredattrs length add dict
  counttomark 2 idiv { dup 4 2 roll put } repeat exch pop
        % Add any missing required attributes.
        % Make a writable and (if possible) local copy of any default
        % dictionaries, to work around a bug in the output of WordPerfect,
        % which assumes that these dictionaries are writable and local.
  .currentglobal exch dup gcheck .setglobal
  //.requiredattrs {
    2 index 2 index known {
      1 index /Policies eq {
        % Merge policies from the device driver with defaults
        2 index             % <<>> /key value <<>>
        3 2 roll get        % <<>> value <<policies>>
        exch {
          2 index 2 index known {
            pop pop
          } {
            2 index 3 1 roll put
          } ifelse
        } forall
        pop
      } {
        pop pop
      } ifelse
    } {
      exec 2 index 3 1 roll put
    } ifelse
  } forall exch .setglobal

  % Remove any keys we don't want to be stored, before .setpagedevice
  % makes the dictionary read only
  .writeonlykeys {2 index exch undef pop} forall
  dup .setpagedevice
} bind def

% Copy a dictionary recursively.
/.copytree {	% <dict> .copytree <dict'>
  dup length dict exch {
    dup type /dicttype eq { .copytree } if 2 index 3 1 roll put
  } forall
} def

/currentpagedevice {
  .currentpagedevice {
    dup length 0 eq {
      pop //.makecurrentpagedevice exec
    } {
                % If any of the dynamic keys have changed,
                % we must update the page device dictionary.
      currentdevice //.volatilepdkeys .getdeviceparams .dicttomark {
                % Stack: current key value
            2 index 2 index .knownget { 1 index ne } { //true } ifelse
             { 2 index wcheck not
                {	% This is the first entry being updated.
                        % Copy the dictionary to make it writable.
                  3 -1 roll
                  currentglobal 1 index dup gcheck currentglobal and setglobal
                  length dict
                  exch setglobal
                  .copydict
                  3 1 roll
                }
               if
               2 index 3 1 roll put
             }
             { pop pop
             }
            ifelse
      } forall
      % If the device is the distiller device, update distillerparams that
      % may have been changed by setdistillerparams
      /IsDistiller /GetDeviceParam .special_op {
        exch pop
      }{
        //false
      }ifelse
      {
          currentdistillerparams {
              % Stack: current key value
            2 index 2 index .knownget { 1 index ne } { //true } ifelse
            { 2 index 3 1 roll put } { pop pop } ifelse
          } forall
      } if
                % If the dictionary was global and is now local, copy
                % any global subsidiary dictionaries to local VM.  This
                % too is to work around the Word Perfect bug (see above).
      dup gcheck not {
        dup {
          dup type /dicttype eq { dup gcheck } { //false } ifelse {
                % Copy-on-write, see above.
            2 index wcheck not {
              3 -1 roll dup length dict .copydict
              3 1 roll
            } if
            //.copytree exec 2 index 3 1 roll put
          } {
            pop pop
          } ifelse
        } forall
      } if
                % We would like to do a .setpagedevice so we don't keep
                % re-creating the dictionary.  Unfortunately, the effect
                % of this is that if any dynamic key changes (PageCount
                % in particular), we will do the equivalent of a
                % setpagedevice at the next restore or grestore.
                % Therefore, we make the dictionary read-only, but
                % we don't store it away.  I.e., NOT:
                % dup wcheck { .setpagedevice .currentpagedevice pop } if
      readonly
    } ifelse
  } if
} bind odef

% Define access to device defaults.
/.defaultdeviceparams
 { finddevice //null .getdeviceparams
 } bind def

% Select media (input or output).  The hard work is done in an operator:
%	<pagedict> <attrdict> <policydict> <keys> .matchmedia <key> true
%	<pagedict> <attrdict> <policydict> <keys> .matchmedia false
%	<pagedict> null <policydict> <keys> .matchmedia null true
/.selectmedia		% <orig> <request> <merged> <failed>     <-- retained
                        %   <attrdict> <policydict> <attrkeys> <mediakey>
                        %   .selectmedia
 { 5 index 5 -2 roll 4 index .matchmedia
                % Stack: orig request merged failed attrkeys mediakey
                %   (key true | false)
    { 4 index 3 1 roll put pop
    }
    {	% Adobe's implementations have a "big hairy heuristic"
        % to choose the set of keys to report as having failed the match.
        % For the moment, we report any keys that are in the request
        % and don't have the same value as in the original dictionary.
      5 index 1 index .knownget
       { 4 index 3 1 roll put }
       { 3 index exch .undef }
      ifelse
       {	% Stack: <orig> <request> <merged> <failed> <attrkey>
         3 index 1 index .knownget
          { 5 index 2 index .knownget { ne } { pop //true } ifelse }
          { //false }
         ifelse		% Stack: ... <failed> <attrkey> <report>
          { 2 copy /rangecheck put }
         if pop
       }
      forall
    }
   ifelse
 } bind def

% Apply Policies to any unprocessed failed requests.
% As we process each request entry, we replace the error name
% in the <failed> dictionary with the policy value,
% and we replace the key in the <merged> dictionary with its prior value
% (or remove it if it had no prior value).

% These procedures are called with the following on the stack:
%   <orig> <merged> <failed> <Policies> <key> <policy>
% They are expected to consume the top 2 operands.
% NOTE: we currently treat all values other than 0, 1, or 7 (for PageSize)
% the same as 0, i.e., we signal an error.
/0Policy {		% Set errorinfo and signal a configurationerror.
  NOMEDIAATTRS {
    % NOMEDIAATTRS means that the default policy is 7...
    pop 2 index exch 7 put
  } {
    pop dup 4 index exch get 2 array astore
    $error /errorinfo 3 -1 roll put
    cleartomark
    /setpagedevice .systemvar /configurationerror signalerror
  } ifelse
} bind executeonly odef

% Making this an operator means we can properly hide
% the contents - specifically .forceput
/1Policy
{
  % Roll back the failed request to its previous status.
  SETPDDEBUG { (Rolling back.) = pstack flush } if
  3 index 2 index 3 -1 roll .forceput
  4 index 1 index .knownget
  { 4 index 3 1 roll .forceput } executeonly
  { 3 index exch .undef }
  ifelse
} bind executeonly odef

/7Policy {		% For PageSize only, just impose the request.
  1 index /PageSize eq
  { pop pop 1 index /PageSize 7 put }
  { .policyprocs 0 get exec }
  ifelse
} bind executeonly odef

/.applypolicies		% <orig> <merged> <failed> .applypolicies
                        %   <orig> <merged'> <failed'>
{
  1 index /Policies get 1 index
  { type /integertype eq
     {
       pop		% already processed
     }{
       2 copy .knownget not { 1 index /PolicyNotFound get } if
                      % Stack: <orig> <merged> <failed> <Policies> <key>
                      %   <policy>
        dup 1 eq {
          1Policy
        }{
          dup 7 eq {
            7Policy
          }{
            0Policy
          } ifelse
        } ifelse
     } ifelse
  }
  forall pop
} .bind executeonly odef

currentdict /0Policy undef
currentdict /1Policy undef
currentdict /7Policy undef

% Put device parameters without resetting currentpagedevice.
% (.putdeviceparams clears the current page device.)
/.putdeviceparamsonly	% <device> <Policies|null> <require_all> -mark-
                        %   <key1> <value1> ... .putdeviceparamsonly
                        % On success: <device> <eraseflag>
                        % On failure: <device> <Policies|null> <req_all> -mark-
                        %   <key1> <error1> ...
 { .currentpagedevice
    { counttomark 4 add 1 roll .putdeviceparams
      dup type /booleantype eq { 3 } { counttomark 5 add } ifelse -1 roll
      .setpagedevice
    }
    { pop .putdeviceparams
    }
   ifelse
 } bind def


/.postinstall {		% mark ... <failed> <merged> .postinstall -
   matrix currentmatrix .setdefaultmatrix
                % Erase and initialize the page.
   initgraphics
   currentoverprint //false setoverprint 1 setcolor
   .fillpage
   0 setcolor setoverprint
   .beginpage

                % Clean up, calling PolicyReport if needed.
                % Stack: mark ... <failed> <merged>
SETPDDEBUG { (Finishing.) = pstack flush } if

   exch dup length 0 ne
    { 1 index /Policies get /PolicyReport get
      counttomark 1 add 2 roll cleartomark
      exec
    }
    { cleartomark
    }
   ifelse pop

} def

% ---------------- setpagedevice itself ---------------- %

/setpagedevice
 {
                % To avoid VM mismatches caused by copying subsidiary
                % dictionaries to local VM (see WorPerfect bug in
                % .makecurrentpagedevice) we want to make the dict
                % returned by currentpagedevice local. However, if we
                % run with -dSAFER we get a call to setpagedevice from
                % .setsafe in gs_init.ps during startup. The dict returned
                % by currentpagdevice is stored to the graphics state by
                % .setpagedevice below, and returned by currentpagdevice.
                % The Display PostScript code insists that the savedinitialgstate
                % not have any pointers to local VM objects, so if we simply
                % make the dict local then we fail in gs_dps.ps. The only
                % solution is to make sure the VM mode is global during
                % startup (to satisfy gs_dps.ps) and local thereafter
                % (to satisfy the WordPerfect bug).
   dup /..StartupGlobal known
   {
       currentglobal exch //true setglobal
       dup /..StartupGlobal undef
   } {
                % ensure that we are always in local VM mode to avoid
                % mismatches. This is because we always create child
                % dictionaries in local VM, regardless of the current VM state,
                % (see .makecurrentpagdevice) and we can't store local objects
                % in a global object, so we must ensure teh dictionary returned
                % from currentpagedevice is in local VM.
     currentglobal exch //false setglobal
   } ifelse

   %% We used to execute endpage after .tsrysetparams, but that actually alters
   %% the page device dictionary (in particular /PageSize) this is not correct.
   %% Testing with Adobe Acrobat Distiller shows that EndPage is ececuted if the
   %% page device dictionary is empty, and indeed even if setpagedevice returns
   %% an error (caught by stopped), so it seems pretty clear that we should
   %% run any required EndPage very early in the setpagedevice process.
   %% Bug 690667.
   2 .endpage
   { 1 //true .outputpage
     (>>setpagedevice, press <return> to continue<<\n) //.confirm exec
   }
   if
                % We mustn't pop the argument until the very end,
                % so that the pseudo-operator machinery can restore the stack
                % if an error occurs.
   mark 1 index currentpagedevice

                % Check whether we are changing OutputDevice;
                % also handle the case where the current device
                % is not a page device.
                % Stack: mark <request> <current>
SETPDDEBUG { (Checking.) = pstack flush } if

   dup /OutputDevice .knownget
    {		% Current device is a page device.
      2 index /OutputDevice .knownget
       {	% A specific OutputDevice was requested.
         2 copy eq
          { pop pop //null }
          { exch pop }
         ifelse
       }
       { pop //null
       }
      ifelse
    }
    {		% Current device is not a page device.
                % Use the default device.
      1 index /OutputDevice .knownget not { .defaultdevicename } if
    }
   ifelse
   dup //null eq
    { pop
    }
    { exch pop //.defaultdeviceparams exec
                % In case of duplicate keys, .dicttomark takes the entry
                % lower on the stack, so we can just append the defaults here.
      //.requiredattrs { exec } forall .dicttomark
    }
   ifelse

                % Check whether a viewer wants to intervene.
                % We must check both the request (which takes precedence)
                % and the current dictionary.
                % Stack: mark <request> <orig>
   exch dup /ViewerPreProcess .knownget
    { exec }
    { 1 index /ViewerPreProcess .knownget { exec } if }
   ifelse exch

                % Construct a merged request from the actual request plus
                % any keys that should always be propagated.
                % Stack: mark <request> <orig>
SETPDDEBUG { (Merging.) = pstack flush } if

   exch 1 index length 1 index length add dict
   .copiedkeys
    {		% Stack: <orig> <request> <merged> <key>
      3 index 1 index .knownget { 3 copy put pop } if pop
    }
   forall
                % Stack: <orig> <request> <merged>
   dup 2 index
    {		% stack: <orig> <request> <merged> <merged> <rkey> <rvalue>
      //.mergespecial 2 index .knownget { exec } if
      put dup
    }
   forall pop
                % Hack: if FIXEDRESOLUTION is true, discard any attempt to
                % change HWResolution.
   FIXEDRESOLUTION { dup /HWResolution .undef } if
                % Hack: if FIXEDMEDIA is true, discard any attempt to change
                % PageSize or HWSize unless the PageSize Policy 13 (for FitPage).
   dup /Policies get /PageSize get 13 ne FIXEDMEDIA and
    { dup /PageSize 4 index /PageSize get put
      dup /HWSize 4 index /HWSize get put
    } if
                % Hack: to work around some files that take a PageSize
                % from InputAttributes and impose it, discard any attempt
                % to set PageSize to a 4-element value.
                % Stack: mark <orig> <request> <merged>
    dup /PageSize .knownget {
      length 2 ne {
        dup /PageSize 4 index /PageSize get put
      } if
    } if

                % Select input and output media.
                % Stack: mark <orig> <request> <merged>
SETPDDEBUG { (Selecting.) = pstack flush } if

   0 dict	% <failed>
   1 index /InputAttributes .knownget
    { 2 index /Policies get
      .inputattrkeys (%MediaSource) cvn //.selectmedia exec
    } if
   1 index /OutputAttributes .knownget
    { 2 index /Policies get
      .outputattrkeys (%MediaDestination) cvn //.selectmedia exec
     } if
   3 -1 roll 4 1 roll		% temporarily swap orig & request
   .applypolicies
   3 -1 roll 4 1 roll		% swap back

                % Construct the new device, and attempt to set its attributes.
                % Stack: mark <orig> <request> <merged> <failed>
SETPDDEBUG { (Constructing.) = pstack flush } if

   % Non-obvious: we need to check the name of the output device, to tell
   % whether we're going to have to replace the entire device chain (which
   % may be only one device, or may be multiple devices.
   % If we're not replacing the entire change, we have to use the device in
   % the graphics state, so the configuration of the entire device chain is
   % correctly set.
   .currentoutputdevice .devicename 2 index /OutputDevice get eq
    { currentdevice }
    { 1 index /OutputDevice get finddevice }
   ifelse
                %**************** We should copy the device here,
                %**************** but since we can't close the old device,
                %**************** we don't.  This is WRONG.
        %****************copydevice
   2 index /Policies get
   //.trysetparams
   dup type /booleantype ne
    {		% The request failed.
                % Stack: ... <orig> <request> <merged> <failed> <device>
                %   <Policies> true mark <name> <errorname> ...
SETPDDEBUG { (Recovering.) = pstack flush } if
      counttomark 4 add index
      counttomark 2 idiv { dup 4 -2 roll put } repeat
      pop pop pop
                % Stack: mark ... <orig> <request> <merged> <failed> <device>
                %   <Policies>
      6 2 roll 3 -1 roll 4 1 roll
      .applypolicies
      3 -1 roll 4 1 roll 6 -2 roll
      //.trysetparams		% shouldn't fail!
      dup type /booleantype ne
       { 2 { counttomark 1 add 1 roll cleartomark } repeat
         /setpagedevice .systemvar exch signalerror
       }
      if
    }
   if

                % The attempt succeeded.  Install the new device.
                % Stack: mark ... <merged> <failed> <device> <eraseflag>
SETPDDEBUG { (Installing.) = pstack flush } if

   pop
                % .setdevice clears the current page device!
   .currentpagedevice pop exch
   { .setdevice } stopped {
     cleartomark exch pop
     /setpagedevice cvx $error /errorname get
     signalerror
   } if
   pop
   .setpagedevice

                % Implement UseCIEColor directly if this is a LL3 system.
                % The color substitution feature is now implemented in
                % the interpreter, and this is used as an optimization.
                %
                % NB: This shoud be the only use of the .setuseciecolor
                %     operator anywhere.
                %
                % Set some color space other than /DeviceGray, to insure
                % that initgraphics will actually perform a setcolorspace
                % operation (there is an optimization in setcolorspace
                % that does nothing if the operand and current color
                % spaces are the same)

    /.setuseciecolor where
      {
        pop 1 index /UseCIEColor .knownget
          {
            .setuseciecolor /DeviceRGB setcolorspace
          }
        if
      }
    if

                % Merge the request into the current page device,
                % unless we're changing the OutputDevice.
                % Stack: mark ... <merged> <failed>
   exch currentpagedevice dup length 2 index length add dict
                % Stack: mark ... <failed> <merged> <current> <newdict>
   2 index /OutputDevice .knownget {
     2 index /OutputDevice .knownget not { //null } if eq
   } {
     //true
   } ifelse {
                % Same OutputDevice, merge the dictionaries.
     .copydict
   } {
                % Different OutputDevice, discard the old dictionary.
     exch pop
   } ifelse .copydict
                % Initialize the default matrix, taking media matching
                % into account.
   //.computemediasize exec pop initmatrix concat
   dup /PageOffset .knownget
    {		% Translate by the given number of 1/72" units in device X/Y.
      dup 0 get exch 1 get
      2 index /HWResolution get dup 1 get exch 0 get
      4 -1 roll mul 72 div   3 1 roll mul 72 div
      idtransform translate
    }
   if
                % We must install the new page device dictionary
                % before calling the Install procedure.
  dup .setpagedevice
  /HighLevelDevice /GetDeviceParam .special_op {
    exch pop not
  }{
    //true
  }ifelse
  {
  .setdefaulthalftone	% Set the default screen before calling Install.
  } if
  dup /Install .knownget {
    { .execinstall } stopped {
      pop % Install procedure failed. One element will have been left on the stack.
      % stack: mark <orig> <request> <failed> <merged>
      1 index /Install $error /errorname get put	% Put it in the "failed" dict
      % .applypolicies needs stack: <orig> <merged> <failed>
      exch 4 2 roll exch 4 2 roll .applypolicies exch 4 2 roll exch 4 2 roll
      % Now execute the old Install -- failures after this are not handled
      dup /Install .knownget { { .execinstall } stopped { pop } if } if
      //.postinstall exec stop
    } {
      //.postinstall exec
    } ifelse
  } {
    //.postinstall exec
  } ifelse
  setglobal           % return to original VM allocation mode
} .bind executeonly odef

% We break out the code after calling the Install procedure into a
% separate procedure, since it is executed even if Install causes an error.
% By making .execinstall a separate operator procedure, we get the stacks
% mostly restored if it fails, except for one element (the operand).
% Thus if it fails, there will be one element left on the op stack.

/.execinstall {		% <proc> .execinstall -
  dup	% element left on the stack if the exec fails.

        % Because the interpreter optimizes tail calls, we can't just let
        % the body of this procedure be 'exec', because that would lose
        % the stack protection that is the whole reason for having the
        % procedure in the first place. The 'pop' for the dummy element
        % on the op stack suffices.
  exec
  pop	% See above.
} odef

[
    /.computemediasize
    /.prepareparams
    /.selectmedia
    /.trysetparams
    /.installpagedevice
    /.postinstall
    /.defaultdeviceparams
    /.makecurrentpagedevice
    /.mergespecial
    /.requiredattrs
    /.applypolicies
%    /.copytree
%    /.uninstallpagedevice % (called from C code)
] dup currentdict .undefinternalnames
systemdict .undefinternalnames

end				% level2dict
.setlanguagelevel
