DP = destination pointer
  SP = source pointer
  Source and Dest are the two buffers


  SP:=0;
  DP:=0;
  repeat
    Com:=Source[SP];
    inc(SP);
    b7:=Com shr 7;  {b7 is bit 7 of Com}
    case b7 of
      0 : begin  {copy command (2)}
            {Count is bits 4-6 + 3}
            Count:=(Com and $7F) shr 4 + 3;
            {Position is bits 0-3, with bits 0-7 of next byte}
            Posit:=(Com and $0F) shl 8+Source[SP];
            Inc(SP);
            {Starting pos=Cur pos. - calculated value}
            Posit:=DP-Posit;
            for i:=Posit to Posit+Count-1 do
            begin
              Dest[DP]:=Dest[i];
              Inc(DP);
            end;
          end;
      1 : begin
            {Check bit 6 of Com}
            b6:=(Com and $40) shr 6;
            case b6 of
              0 : begin  {Copy as is command (1)}
                    Count:=Com and $3F;  {mask 2 topmost bits}
                    if Count=0 then break; {EOF marker}
                    for i:=1 to Count do
                    begin
                      Dest[DP]:=Source[SP];
                      Inc(DP);
                      Inc(SP);
                    end;
                  end;
              1 : begin  {large copy, very large copy and fill commands}
                    {Count = (bits 0-5 of Com) +3}
                    {if Com=FEh then fill, if Com=FFh then very large copy}
                    Count:=Com and $3F;
                    if Count<$3E then {large copy (3)}
                    begin
                      Inc(Count,3);
                      {Next word = pos. from start of image}
                      Posit:=Word(Source[SP]);
                      Inc(SP,2);
                      for i:=Posit to Posit+Count-1 do
                      begin
                        Dest[DP]:=Dest[i];
                        Inc(DP);
                      end;
                    end
                    else if Count=$3F then   {very large copy (5)}
                    begin
                      {next 2 words are Count and Pos}
                      Count:=Word(Source[SP]);
                      Posit:=Word(Source[SP+2]);
                      Inc(SP,4);
                      for i:=Posit to Posit+Count-1 do
                      begin
                        Dest[DP]:=Dest[i];
                        Inc(DP);
                      end;
                    end else
                    begin   {Count=$3E, fill (4)}
                      {Next word is count, the byte after is color}
                      Count:=Word(Source[SP]);
                      Inc(SP,2);
                      b:=Source[SP];
                      Inc(SP);
                      for i:=0 to Count-1 do
                      begin
                        Dest[DP]:=b;
                        inc(DP);
                      end;
                    end;
                  end;
            end;
          end;
    end;
  until false;