Compacting Symbol Tables

After each module is compiled the symbol tables are compacted to remove unused space.
Procedure JoinSymbolTablesAndCreateUnit;
Var ReferencedUnitRecord: PReferencedModulesBlockRecord;
    SymbolsSize: LongRec;
    Block: TSymbolTable;
    UnitHeader: PUnitHeader;
    CurrentPointer: PChar;
  Function AdjustCurrentPointerToNextParagraph: Word;
  begin
    AdjustCurrentPointerToNextParagraph := Seg (CurrentPointer^);
    FillChar (CurrentPointer^, (16 - Ofs (CurrentPointer^)) and $000F, 0);
    Inc (CurrentPointer, (16 - Ofs (CurrentPointer^)) and $000F);
    CurrentPointer := Ptr (Seg (CurrentPointer^) + Ofs (CurrentPointer^) shr 4, 0);
  end;

begin
  ReferencedUnitRecord := Ptr (SymbolTable [stReferencedModules].Segment, 0);
  While ReferencedUnitRecord <> SymbolTable [stReferencedModules].Ptr do
    begin
      ReferencedUnitRecord^.ModuleSegment := 0;
      Inc (PChar (ReferencedUnitRecord), ReferencedUnitRecord^.UnitName.Len + 5);
    end;
  SymbolsSize.Long := 0;
  For Block := stMain to stSourceLineCodeOffsets do
    Inc (SymbolsSize.Long, SymbolTable [Block].UsedSize);
  If SymbolsSize.WordH <> 0 then Error (TooManySymbols);
  If SymbolsSize.WordL > $FFF0 then Error (TooManySymbols);
  UnitHeader := Ptr (SymbolTable [stMain].Segment, 0);
  CurrentPointer := SymbolTable [stMain].Ptr;
  For Block := stProcedures to stSourceLineCodeOffsets do
    begin
      UnitHeader^.BlockOffset [Block] := Ofs (CurrentPointer^);
      MoveBackward (Ptr (SymbolTable [Block].Segment, 0)^, CurrentPointer^, SymbolTable [Block].UsedSize);
      Inc (CurrentPointer, SymbolTable [Block].UsedSize);
    end;
  SymbolTable [stMain].UsedSize := Ofs (CurrentPointer^);
  UnitHeader^.JoinedBlockSize := Ofs (CurrentPointer^);
  For Block := st11 to stTypedConstantsReferences do
    UnitHeader^.BlockSize [Block] := SymbolTable [Block].UsedSize;
  UnitHeader^.SizeOfVariablesInDataSegment := SizeOfVariablesInDataSegment;
  AdjustCurrentPointerToNextParagraph;
  For Block := st11 to stTypedConstantsReferences do
    begin
      MoveBackward (Ptr (SymbolTable [Block].Segment, 0)^, CurrentPointer^, SymbolTable [Block].UsedSize);
      Inc (CurrentPointer, SymbolTable [Block].UsedSize);
      SymbolTable [Block].Segment := AdjustCurrentPointerToNextParagraph;
    end;
  HeapPtr := CurrentPointer;
end;
 
 
 
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