docview: Enabled support for reading images from INF files. (WIP)

This is still Work-In-Progress because the images are displayed, but
sometimes incorrectly, or with a wrong color palette. Either way, this
is progress, and very long overdue. ;-)

5 files changed, 304 insertions, 256 deletions

diff --git a/docview/src/HelpBitmap.pas b/docview/src/HelpBitmap.pas
index ecce808f..692bf64d 100644
--- a/docview/src/HelpBitmap.pas
+++ b/docview/src/HelpBitmap.pas
@@ -26,7 +26,7 @@ unit HelpBitmap;
 interface
 
 uses
-  Classes, SysUtils, fpg_main, ctypes,
+  Classes, SysUtils, fpg_main,
   IPFFileFormatUnit;
 
 type
@@ -83,7 +83,6 @@ type
     _UncompressedBlockSize: longint;
     function GetPaletteSize: longint;
     procedure BitmapError(Msg: string);
-    procedure DecompressLZW(var Buffer: Pointer; const Count: integer; var NewBuffer: PByte; var NewCount: integer);
     procedure ReadBitmapData( Blocks: TList; TotalSize: longint );
   public
     constructor CreateFromHelpFile(var AFileHandle: TFileStream; Offset: longint);
@@ -91,19 +90,13 @@ type
   end;
 
 
-var
-  LZWDecompressBlock: function( pInput: PBYTE;
-                               pOutput: PBYTE;
-                               bytesIn: uint32;
-                               Var bytesOut: uint32;
-                               Var FinalCode: byte ): Boolean;
-//  APIENTRY;
-//  'newview' index 1;
-
 implementation
 
 uses
-  nvUtilities, Math, fpg_imgfmt_bmp;
+  nvUtilities,
+  Math,
+  LZWDecompress,
+  fpg_imgfmt_bmp;
 
 const
   BFT_bMAP =$4d62; // 'bM'
@@ -120,9 +113,15 @@ type
     _Size: uint16;
     _CompressionType: uint8;
     _Data: PBYTE;
+    constructor Create;
     destructor Destroy; override;
   end;
 
+constructor TBitmapBlock.Create;
+begin
+  _Data := nil;
+end;
+
 destructor TBitmapBlock.Destroy;
 begin
   FreeMem( _Data );
@@ -137,7 +136,6 @@ var
   BytesRead: longint;
 
   Block: TBitmapBlock;
-  p: pointer;
   Blocks: TList;
   BlockIndex: longint;
   ImageType: uint16;
@@ -172,7 +170,8 @@ begin
   if _Header.usType <> BFT_bMAP then
     raise EHelpBitmapException.Create( 'Invalid bitmap header' );
 
-  _Header.usType := $4d42; // sibyl only accepts 'BM' not 'bM'
+// Graeme: we don't need to do this any more. It was only for Sybil
+//  _Header.usType := $4d42; // sibyl only accepts 'BM' not 'bM'
 
   // We can only parse bitmaps with 1 colour plane
   // (I can't be bothered and have never seen bitmaps
@@ -192,7 +191,7 @@ begin
   _BitsSize := LineSize * _Header.cy;
 
   // Correct header offset - it is wrong in the header (why?)
-  _Header.OffBits := sizeof( _Header ) + GetPaletteSize;           // TODO: Graeme, double check this!
+  _Header.OffBits := sizeof( _Header ) + GetPaletteSize;
 
   // Load palette
   if _Header.cBitCount <= 8 then
@@ -204,7 +203,7 @@ begin
   end;
 
   // Read data header
-  FillChar( DataHeader, sizeof( DataHeader ), 0 );
+//  FillChar( DataHeader, sizeof( DataHeader ), 0 );
   bytes := FileHandle.Read(DataHeader, SizeOf(DataHeader));
   if bytes <> SizeOf(DataHeader) then
     raise EHelpBitmapException.Create( 'Failed to read DataHeader.' );
@@ -268,227 +267,7 @@ begin
   inherited Destroy;
 end;
 
-procedure THelpBitmap.DecompressLZW(var Buffer: Pointer; const Count: Integer; var NewBuffer: PByte; var NewCount: integer);
-type
-  TLZWString = packed record
-    Count: integer;
-    Data: PByte;
-  end;
-  PLZWString = ^TLZWString;
-const
-  ClearCode = 256; // clear table, start with 9bit codes
-  EoiCode = 257; // end of input
-var
-//  NewBuffer: PByte;
-//  NewCount: PtrInt;
-  NewCapacity: PtrInt;
-  SrcPos: PtrInt;
-  SrcPosBit: integer;
-  CurBitLength: integer;
-  Code: Word;
-  Table: PLZWString;
-  TableCapacity: integer;
-  TableCount: integer;
-  OldCode: Word;
-
-  function GetNextCode: Word;
-  var
-    v: Integer;
-  begin
-    Result:=0;
-    // CurBitLength can be 9 to 12
-    //writeln('GetNextCode CurBitLength=',CurBitLength,' SrcPos=',SrcPos,' SrcPosBit=',SrcPosBit,' ',hexstr(PByte(Buffer)[SrcPos],2),' ',hexstr(PByte(Buffer)[SrcPos+1],2),' ',hexstr(PByte(Buffer)[SrcPos+2],2));
-    // read two or three bytes
-    if CurBitLength+SrcPosBit>16 then begin
-      // read from three bytes
-      if SrcPos+3>Count then BitmapError('LZW stream overrun');
-      v:=PByte(Buffer)[SrcPos];
-      inc(SrcPos);
-      v:=(v shl 8)+PByte(Buffer)[SrcPos];
-      inc(SrcPos);
-      v:=(v shl 8)+PByte(Buffer)[SrcPos];
-      v:=v shr (24-CurBitLength-SrcPosBit);
-    end else begin
-      // read from two bytes
-      if SrcPos+2>Count then BitmapError('LZW stream overrun');
-      v:=PByte(Buffer)[SrcPos];
-      inc(SrcPos);
-      v:=(v shl 8)+PByte(Buffer)[SrcPos];
-      if CurBitLength+SrcPosBit=16 then
-        inc(SrcPos);
-      v:=v shr (16-CurBitLength-SrcPosBit);
-    end;
-    Result:=v and ((1 shl CurBitLength)-1);
-    SrcPosBit:=(SrcPosBit+CurBitLength) and 7;
-    //writeln('GetNextCode END SrcPos=',SrcPos,' SrcPosBit=',SrcPosBit,' Result=',Result,' Result=',hexstr(Result,4));
-  end;
-
-  procedure ClearTable;
-  var
-    i: Integer;
-  begin
-    for i:=0 to TableCount-1 do
-      ReAllocMem(Table[i].Data,0);
-    TableCount:=0;
-  end;
-
-  procedure InitializeTable;
-  begin
-    CurBitLength:=9;
-    ClearTable;
-  end;
-
-  function IsInTable(Code: word): boolean;
-  begin
-    Result:=Code<258+TableCount;
-  end;
-
-  procedure WriteStringFromCode(Code: integer; AddFirstChar: boolean = false);
-  var
-    s: TLZWString;
-    b: byte;
-  begin
-    //WriteLn('WriteStringFromCode Code=',Code,' AddFirstChar=',AddFirstChar,' x=',(NewCount div 4) mod IDF.ImageWidth,' y=',(NewCount div 4) div IDF.ImageWidth,' PixelByte=',NewCount mod 4);
-    if Code<256 then begin
-      // write byte
-      b:=Code;
-      s.Data:=@b;
-      s.Count:=1;
-    end else if Code>=258 then begin
-      // write string
-      if Code-258>=TableCount then
-        BitmapError('LZW code out of bounds');
-      s:=Table[Code-258];
-    end else
-      BitmapError('LZW code out of bounds');
-    if NewCount+s.Count+1>NewCapacity then begin
-      NewCapacity:=NewCapacity*2+8;
-      ReAllocMem(NewBuffer,NewCapacity);
-    end;
-    System.Move(s.Data^,NewBuffer[NewCount],s.Count);
-    //for i:=0 to s.Count-1 do write(HexStr(NewBuffer[NewCount+i],2)); // debug
-    inc(NewCount,s.Count);
-    if AddFirstChar then begin
-      NewBuffer[NewCount]:=s.Data^;
-      //write(HexStr(NewBuffer[NewCount],2)); // debug
-      inc(NewCount);
-    end;
-    //writeln(',WriteStringFromCode'); // debug
-  end;
-
-  procedure AddStringToTable(Code, AddFirstCharFromCode: integer);
-  // add string from code plus first character of string from code as new string
-  var
-    b1, b2: byte;
-    s1, s2: TLZWString;
-    p: PByte;
-  begin
-    //WriteLn('AddStringToTable Code=',Code,' FCFCode=',AddFirstCharFromCode,' TableCount=',TableCount,' TableCapacity=',TableCapacity);
-    // grow table
-    if TableCount>=TableCapacity then begin
-      TableCapacity:=TableCapacity*2+128;
-      ReAllocMem(Table,TableCapacity*SizeOf(TLZWString));
-    end;
-    // find string 1
-    if Code<256 then begin
-      // string is byte
-      b1:=Code;
-      s1.Data:=@b1;
-      s1.Count:=1;
-    end else if Code>=258 then begin
-      // normal string
-      if Code-258>=TableCount then
-        BitmapError('LZW code out of bounds');
-      s1:=Table[Code-258];
-    end else
-      BitmapError('LZW code out of bounds');
-    // find string 2
-    if AddFirstCharFromCode<256 then begin
-      // string is byte
-      b2:=AddFirstCharFromCode;
-      s2.Data:=@b2;
-      s2.Count:=1;
-    end else begin
-      // normal string
-      if AddFirstCharFromCode-258>=TableCount then
-        BitmapError('LZW code out of bounds');
-      s2:=Table[AddFirstCharFromCode-258];
-    end;
-    // set new table entry
-    Table[TableCount].Count:=s1.Count+1;
-    p:=nil;
-    GetMem(p,s1.Count+1);
-    Table[TableCount].Data:=p;
-    System.Move(s1.Data^,p^,s1.Count);
-    // add first character from string 2
-    p[s1.Count]:=s2.Data^;
-    // increase TableCount
-    inc(TableCount);
-    case TableCount+259 of
-      512,1024,2048: inc(CurBitLength);
-      4096: BitmapError('LZW too many codes');
-    end;
-  end;
-
-begin
-  if Count=0 then exit;
-  //WriteLn('TFPReaderTiff.DecompressLZW START Count=',Count);
-  //for SrcPos:=0 to 19 do
-  //  write(HexStr(PByte(Buffer)[SrcPos],2));
-  //writeln();
-
-  NewBuffer:=nil;
-  NewCount:=0;
-  NewCapacity:=Count*2;
-  ReAllocMem(NewBuffer,NewCapacity);
-
-  SrcPos:=0;
-  SrcPosBit:=0;
-  CurBitLength:=9;
-  Table:=nil;
-  TableCount:=0;
-  TableCapacity:=0;
-  try
-    repeat
-      Code:=GetNextCode;
-      //WriteLn('TFPReaderTiff.DecompressLZW Code=',Code);
-      if Code=EoiCode then break;
-      if Code=ClearCode then begin
-        InitializeTable;
-        Code:=GetNextCode;
-        //WriteLn('TFPReaderTiff.DecompressLZW after clear Code=',Code);
-        if Code=EoiCode then break;
-        if Code=ClearCode then
-          BitmapError('LZW code out of bounds');
-        WriteStringFromCode(Code);
-        OldCode:=Code;
-      end else begin
-        if Code<TableCount+258 then begin
-          WriteStringFromCode(Code);
-          AddStringToTable(OldCode,Code);
-          OldCode:=Code;
-        end else if Code=TableCount+258 then begin
-          WriteStringFromCode(OldCode,true);
-          AddStringToTable(OldCode,OldCode);
-          OldCode:=Code;
-        end else
-          BitmapError('LZW code out of bounds');
-      end;
-    until false;
-  finally
-    ClearTable;
-    ReAllocMem(Table,0);
-  end;
-
-  ReAllocMem(NewBuffer,NewCount);
-//  FreeMem(Buffer);
-//  Buffer:=NewBuffer;
-//  Count:=NewCount;
-end;
-
-
-procedure THelpBitmap.ReadBitmapData( Blocks: TList;
-                                      TotalSize: longint );
+procedure THelpBitmap.ReadBitmapData( Blocks: TList; TotalSize: longint );
 var
   BytesWritten: longint;
   BytesWrittenFromBlock: longword;
@@ -501,13 +280,15 @@ var
   BlockIndex: longint;
   BitmapData: PBYTE;
   ptr: PByte;
+  i: integer;
+  img: TfpgImage;
 begin
   BitmapOutputPointer := nil;
   BitmapData := nil;
   ptr := nil;
 
   // Allocate memory to store the bitmap
-  Bitmapdata := GetMem( TotalSize );
+  BitmapData := GetMem( TotalSize );
 
   // Copy header to bitmap
   MemCopy( _Header, BitmapData^, sizeof( _Header ) );
@@ -535,16 +316,11 @@ begin
 
       2: // LZW compression
       begin
-        // decompress block
-        if not Assigned( LZWDecompressBlock )then
-          raise EHelpBitmapException.Create( 'Cannot decode bitmap - DLL not found' );
-
-//        DecompressLZW(Block._Data, Block._Size);
-        //LZWDecompressBlock( Block._Data,
-        //                    BitmapOutputPointer,
-        //                    Block._Size,
-        //                    BytesWrittenFromBlock,
-        //                    lastOutByte );
+        LZWDecompressBlock( Block._Data,
+                            Block._Size,
+                            BitmapOutputPointer,
+                            BytesWrittenFromBlock,
+                            lastOutByte );
 
         inc( BytesWritten, BytesWrittenFromBlock );
 
@@ -577,9 +353,13 @@ begin
          > BitmapData + TotalSize ) then
       assert( false );
 
-    inc( BitmapOutputPointer, BytesWrittenFromBlock );
+{ NOTE: This doesn't seem right. It moves the pointer so later the moving of data to
+  ImageData will be wrong! }
+//    inc( BitmapOutputPointer, BytesWrittenFromBlock ); TPersistentObjectState
   end;
 
+  i := TotalSize + SizeOf(_Header) + GetPaletteSize;
+  img := CreateImage_BMP(BitmapData, i);
 
   AllocateImage(32, _Header.cx, _Header.cy);
 
@@ -600,10 +380,10 @@ begin
   writeln('------------- END -------------');
   {$ENDIF}
 
-  if TotalSize <> ImageDataSize then
-    writeln('Warning: INF Bitmap size and allocated bitmap size are different. ', TotalSize, ' vs ', ImageDataSize);
-  Move(BitmapData^, ImageData^, TotalSize);
+//  Move(BitmapOutputPointer^, ImageData^, ImageDataSize);
+  Move(img.ImageData^, self.ImageData^, img.ImageDataSize);
   UpdateImage;
+  img.Free;
 
   FreeMem( BitmapData, TotalSize );
 end;
diff --git a/docview/src/docview.lpi b/docview/src/docview.lpi
index aa570406..6fc2c4cb 100644
--- a/docview/src/docview.lpi
+++ b/docview/src/docview.lpi
@@ -23,6 +23,7 @@
     <RunParams>
       <local>
         <FormatVersion Value="1"/>
+        <CommandLineParams Value="/data/devel/tests/inf_test/test2.inf"/>
         <LaunchingApplication PathPlusParams="/usr/X11R6/bin/xterm -T 'Lazarus Run Output' -e $(LazarusDir)/tools/runwait.sh $(TargetCmdLine)"/>
       </local>
     </RunParams>
@@ -31,7 +32,7 @@
         <PackageName Value="fpgui_toolkit"/>
       </Item1>
     </RequiredPackages>
-    <Units Count="36">
+    <Units Count="37">
       <Unit0>
         <Filename Value="docview.lpr"/>
         <IsPartOfProject Value="True"/>
@@ -206,6 +207,11 @@
         <IsPartOfProject Value="True"/>
         <UnitName Value="frm_bookmarks"/>
       </Unit35>
+      <Unit36>
+        <Filename Value="lzwdecompress.pas"/>
+        <IsPartOfProject Value="True"/>
+        <UnitName Value="LZWDecompress"/>
+      </Unit36>
     </Units>
   </ProjectOptions>
   <CompilerOptions>
diff --git a/docview/src/docview.lpr b/docview/src/docview.lpr
index ad71b43a..0bee1dbe 100644
--- a/docview/src/docview.lpr
+++ b/docview/src/docview.lpr
@@ -13,7 +13,7 @@ uses
   RichTextStyleUnit, CanvasFontManager, ACLStringUtility, RichTextDocumentUnit,
   RichTextView, RichTextLayoutUnit, RichTextDisplayUnit, dvconstants, dvHelpers,
   frm_configuration, HelpBitmap, frm_text, frm_note, HelpNote, HelpBookmark,
-  frm_bookmarks;
+  frm_bookmarks, LZWDecompress;
 
 {$IFDEF WINDOWS}
   {$R docview.rc}
diff --git a/docview/src/frm_main.pas b/docview/src/frm_main.pas
index 090916a3..b88b9206 100644
--- a/docview/src/frm_main.pas
+++ b/docview/src/frm_main.pas
@@ -2508,8 +2508,7 @@ begin
 
   if ImageIndices.Count > 0 then
   begin
-  { TODO -oGraeme : We do not support images yet }
-//   THelpFile(CurrentTopic.HelpFile).GetImages(ImageIndices, FImages);
+    THelpFile(CurrentTopic.HelpFile).GetImages(ImageIndices, FImages);
   end;
 
   ImageIndices.Free;
diff --git a/docview/src/lzwdecompress.pas b/docview/src/lzwdecompress.pas
new file mode 100644
index 00000000..5f886f23
--- /dev/null
+++ b/docview/src/lzwdecompress.pas
@@ -0,0 +1,263 @@
+{
+  fpGUI  -  Free Pascal GUI Toolkit
+
+  Copyright (C) 2006 - 2013 See the file AUTHORS.txt, included in this
+  distribution, for details of the copyright.
+
+  See the file COPYING.modifiedLGPL, included in this distribution,
+  for details about redistributing fpGUI.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+  Description:
+    LZW decompression code for uncompressing IPF bitmaps.
+}
+
+unit LZWDecompress;
+
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+  SysUtils, types;
+
+procedure LZWDecompressBlock( pbInput: pByte;
+                              number_bytes: LongWord;
+                              pbOutput: PBYTE;
+                              Var bytesOut: LongWord;
+                              Var FinalCode: byte );
+
+Implementation
+
+(*
+/********************************************************************
+ *                                                                  *
+ *  LZW decompression                                               *
+ *                                                                  *
+ *******************************************************************/
+
+/*
+ *  This is based on code (W) by Peter Fitzsimmons, pfitz@ican.net.
+ *  His liner notes in the original:
+ *      has its roots in a June 1990
+ *      DDJ article "LZW REVISITED", by Shawn M. Regan
+ *      --=>revision history<=--
+ *      1 lzw.c 21-Aug-96,2:24:36,`PLF' ;
+ *      2 lzw.c 24-Aug-96,2:27:24,`PLF' wip
+ *
+ *  The code has been modified to take the input not from an
+ *  open file, but from any memory region. For this, a double
+ *  pointer is used, which must be passed to LZWDecompressBlock.
+ *  I've also added a few comments for clarity.
+ *
+ * Ported to Sibyl Pascal by Aaron Lawrence
+ * Variables renamed etc to make things clearer.
+ */
+*)
+// -- Stuff for LZW decompression -- */
+const INIT_BITS = 9;
+const MAX_BITS = 12;     //PLF Tue  95-10-03 02:16:56*/
+const HASHING_SHIFT = MAX_BITS - 8;
+
+{if MAX_BITS == 15
+const TABLE_SIZE 36768
+#elif MAX_BITS == 14
+const TABLE_SIZE 18041
+#elif MAX_BITS == 13
+const TABLE_SIZE 9029
+#else}
+// For max_bits = 12:
+const TABLE_SIZE = 5021;
+
+const CLEAR_TABLE = 256;
+const TERMINATOR = 257;
+const FIRST_CODE = 258;
+
+function MaxValNBits( N: word ): word;
+begin
+  Result:= ( 1 shl n ) - 1;
+end;
+
+var
+  prefix_code: array[ 0..TABLE_SIZE ] of longword;
+  append_character: array[ 0..TABLE_SIZE ] of Byte;
+  decode_stack: array[ 0..10000 ] of byte;
+  bitsPerCode: longint;
+  maxDictionaryCode: longint;
+
+(*
+ * decode_string:
+ *
+ *)
+function decode_string( buffer: PByte; code: longword ): PByte;
+var
+  i: longint;
+begin
+  i:= 0;
+
+  while Code > 255 do
+  begin
+    buffer^:= append_character[ Code ];
+    inc( Buffer );
+    code:= prefix_code[ code ];
+
+    inc( i );
+    if i > High( decode_stack ) then
+      assert( false, 'Out of space decompressing bitmap!' );
+  end;
+
+  buffer^ := code;
+  Result:= buffer;
+end;
+
+(*
+ * input_code:
+ *      this function reads in bytes from the input
+ *      stream.
+ *)
+
+var
+  bytes_out: longword = 0;
+  input_bit_count: longword = 0;
+  input_bit_buffer: longword = 0;
+
+// I think this simply reads the next bitsPerCode bits of the input data
+// returning the resulting code.
+function input_code( var pbInput: PBYTE; bytes_to_read: longword ): longword;
+var
+  return_value: longword;
+begin
+  while input_bit_count <= 24 do
+  begin
+    if bytes_out <= bytes_to_read then
+    begin
+      input_bit_buffer:= input_bit_buffer
+                         or
+                         ( ( longword( pbInput^ ) shl (24 - input_bit_count) ) );
+      inc( pbInput );
+    end
+    else
+      input_bit_buffer:= input_bit_buffer
+                         or
+                         ( longword( 0 ) << ( 24 - input_bit_count ) );
+    inc( bytes_out );
+    inc( input_bit_count, 8 );
+  end;
+
+  return_value:= input_bit_buffer shr (32 - bitsPerCode);
+  input_bit_buffer:= input_bit_buffer shl bitsPerCode;
+  dec( input_bit_count, bitsPerCode );
+
+  if bytes_out > bytes_to_read then
+  begin
+    // flush static vars and quit */
+    bytes_out:= 0;
+    input_bit_count:= 0;
+    input_bit_buffer:= 0;
+    Result:= TERMINATOR;
+  end
+  else
+    Result:= return_value;
+end;
+
+// LZWDecompressBlock:
+//      this takes one of the INF bitmap blocks
+//      and decompresses it using LZW algorithms.
+
+procedure LZWDecompressBlock( pbInput: pByte;
+                              number_bytes: LongWord;
+                              pbOutput: PBYTE;
+                              Var bytesOut: LongWord;
+                              Var FinalCode: byte );
+var
+  nextAvailableCode: LongWord;
+  currentCode: LongWord;
+  lastCode: LongWord;
+  character: longword;
+  clear_flag: boolean;
+  theString: pByte;
+begin
+  clear_flag:= true;
+
+  nextAvailableCode:= FIRST_CODE;
+  bitsPerCode:= INIT_BITS;
+  maxDictionaryCode:= MaxValNBits( bitsPerCode );
+
+  bytesOut:= 0;
+  input_bit_count:= 0;
+  input_bit_buffer:= 0;
+
+  // read the first code from input
+  currentCode:= input_code( pbInput, number_bytes );
+  while currentCode <> TERMINATOR do
+  begin
+    if clear_flag then
+    begin
+      clear_flag:= false;
+      lastCode:= currentCode;
+      character:= currentCode;
+
+      pbOutput^:= currentCode;
+      inc( pbOutput );
+      FinalCode:= currentCode;
+      inc( BytesOut );
+    end
+    else if currentCode = CLEAR_TABLE then
+    begin
+      clear_flag:= true;
+      nextAvailableCode:= FIRST_CODE;
+      bitsPerCode:= INIT_BITS;
+      maxDictionaryCode:= MaxValNBits( bitsPerCode );
+    end
+    else
+    begin
+      if currentCode >= nextAvailableCode then
+      begin
+         decode_stack[ 0 ]:= character;
+         theString:= decode_string( Addr( decode_stack[ 1 ] ),
+                                    lastCode );
+      end
+      else
+        theString:= decode_string( Addr( decode_stack[ 0 ] ),
+                                   currentCode );
+
+      character:= longword( theString^ );
+      while theString >= Addr( decode_stack[ 0 ] ) do
+      begin
+        FinalCode:= theString^;
+
+        pbOutput^:= theString^;
+        inc( pbOutput );
+        dec( TheString );
+
+        inc( BytesOut );
+      end;
+
+      if nextAvailableCode <= maxDictionaryCode then
+      begin
+        prefix_code[ nextAvailableCode ]:= lastCode;
+        append_character[ nextAvailableCode ]:= character;
+
+        inc( nextAvailableCode );
+
+        if ( nextAvailableCode = maxDictionaryCode ) and ( bitsPerCode < MAX_BITS ) then
+        begin
+          // expand dictionary
+          inc( bitsPerCode );
+          maxDictionaryCode:= MaxValNBits( bitsPerCode );
+        end;
+      end;
+
+      lastCode:= currentCode;
+    end;
+
+    // Read next code from input
+    currentCode:= input_code( pbInput, number_bytes );
+  end;
+end;
+
+
+End.