zdeflate.pas

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  end;
  if s^.noheader <> 0 then
    s^.status := BUSY_STATE
  else
    s^.status := INIT_STATE;
  strm.adler := 1;
  s^.last_flush := Z_NO_FLUSH;

  _tr_init(s^);
  lm_init(s^);

  deflateReset := Z_OK;
end;

{  ======================================================================== }
function deflateParams(var strm : z_stream;
                       level : int;
                       strategy : int) : int;
var
  s : deflate_state_ptr;
  func : compress_func;
  err : int;
begin
  err := Z_OK;
  if {(@strm  =  Z_NULL) or} (strm.state  =  Z_NULL) then
  begin
    deflateParams := Z_STREAM_ERROR;
    exit;
  end;

  s := deflate_state_ptr(strm.state);

  if (level = Z_DEFAULT_COMPRESSION) then
  begin
    level := 6;
  end;
  if (level < 0) or (level > 9) or (strategy < 0)
  or (strategy > Z_HUFFMAN_ONLY) then
  begin
    deflateParams := Z_STREAM_ERROR;
    exit;
  end;
  func := configuration_table[s^.level].func;

  if (@func <> @configuration_table[level].func)
    and (strm.total_in <> 0) then
  begin
      { Flush the last buffer: }
      err := deflate(strm, Z_PARTIAL_FLUSH);
  end;
  if (s^.level <> level) then
  begin
    s^.level := level;
    s^.max_lazy_match   := configuration_table[level].max_lazy;
    s^.good_match       := configuration_table[level].good_length;
    s^.nice_match       := configuration_table[level].nice_length;
    s^.max_chain_length := configuration_table[level].max_chain;
  end;
  s^.strategy := strategy;
  deflateParams := err;
end;

{ =========================================================================
  Put a short in the pending buffer. The 16-bit value is put in MSB order.
  IN assertion: the stream state is correct and there is enough room in
  pending_buf. }

{local}
procedure putShortMSB (var s : deflate_state; b : uInt);
begin
  s.pending_buf^[s.pending] := Byte(b shr 8);
  Inc(s.pending);
  s.pending_buf^[s.pending] := Byte(b and $ff);
  Inc(s.pending);
end;

{ =========================================================================
  Flush as much pending output as possible. All deflate() output goes
  through this function so some applications may wish to modify it
  to avoid allocating a large strm^.next_out buffer and copying into it.
  (See also read_buf()). }

{local}
procedure flush_pending(var strm : z_stream);
var
  len : unsigned;
  s : deflate_state_ptr;
begin
  s := deflate_state_ptr(strm.state);
  len := s^.pending;

  if (len > strm.avail_out) then
    len := strm.avail_out;
  if (len = 0) then
    exit;

  zmemcpy(strm.next_out, s^.pending_out, len);
  Inc(strm.next_out, len);
  Inc(s^.pending_out, len);
  Inc(strm.total_out, len);
  Dec(strm.avail_out, len);
  Dec(s^.pending, len);
  if (s^.pending = 0) then
  begin
    s^.pending_out := pBytef(s^.pending_buf);
  end;
end;

{ ========================================================================= }
function deflate (var strm : z_stream; flush : int) : int;
var
  old_flush : int; { value of flush param for previous deflate call }
  s : deflate_state_ptr;
var
  header : uInt;
  level_flags : uInt;
var
  bstate : block_state;
begin
  if {(@strm = Z_NULL) or} (strm.state = Z_NULL)
    or (flush > Z_FINISH) or (flush < 0) then
  begin
    deflate := Z_STREAM_ERROR;
    exit;
  end;
  s := deflate_state_ptr(strm.state);

  if (strm.next_out = Z_NULL) or
     ((strm.next_in = Z_NULL) and (strm.avail_in <> 0)) or
     ((s^.status = FINISH_STATE) and (flush <> Z_FINISH)) then
  begin
    {ERR_RETURN(strm^, Z_STREAM_ERROR);}
    strm.msg := z_errmsg[z_errbase - Z_STREAM_ERROR];
    deflate := Z_STREAM_ERROR;
    exit;
  end;
  if (strm.avail_out = 0) then
  begin
    {ERR_RETURN(strm^, Z_BUF_ERROR);}
    strm.msg := z_errmsg[z_errbase - Z_BUF_ERROR];
    deflate := Z_BUF_ERROR;
    exit;
  end;

  s^.strm := @strm; { just in case }
  old_flush := s^.last_flush;
  s^.last_flush := flush;

  { Write the zlib header }
  if (s^.status = INIT_STATE) then
  begin

    header := (Z_DEFLATED + ((s^.w_bits-8) shl 4)) shl 8;
    level_flags := (s^.level-1) shr 1;

    if (level_flags > 3) then
      level_flags := 3;
    header := header or (level_flags shl 6);
    if (s^.strstart <> 0) then
      header := header or PRESET_DICT;
    Inc(header, 31 - (header mod 31));

    s^.status := BUSY_STATE;
    putShortMSB(s^, header);

    { Save the adler32 of the preset dictionary: }
    if (s^.strstart <> 0) then
    begin
      putShortMSB(s^, uInt(strm.adler shr 16));
      putShortMSB(s^, uInt(strm.adler and $ffff));
    end;
    strm.adler := long(1);
  end;

  { Flush as much pending output as possible }
  if (s^.pending <> 0) then
  begin
    flush_pending(strm);
    if (strm.avail_out = 0) then
    begin
      { Since avail_out is 0, deflate will be called again with
	more output space, but possibly with both pending and
	avail_in equal to zero. There won't be anything to do,
	but this is not an error situation so make sure we
	return OK instead of BUF_ERROR at next call of deflate: }

      s^.last_flush := -1;
      deflate := Z_OK;
      exit;
    end;

  { Make sure there is something to do and avoid duplicate consecutive
    flushes. For repeated and useless calls with Z_FINISH, we keep
    returning Z_STREAM_END instead of Z_BUFF_ERROR. }

  end
  else
    if (strm.avail_in = 0) and (flush <= old_flush)
      and (flush <> Z_FINISH) then
    begin
      {ERR_RETURN(strm^, Z_BUF_ERROR);}
      strm.msg := z_errmsg[z_errbase - Z_BUF_ERROR];
      deflate := Z_BUF_ERROR;
      exit;
    end;

  { User must not provide more input after the first FINISH: }
  if (s^.status = FINISH_STATE) and (strm.avail_in <> 0) then
  begin
    {ERR_RETURN(strm^, Z_BUF_ERROR);}
    strm.msg := z_errmsg[z_errbase - Z_BUF_ERROR];
    deflate := Z_BUF_ERROR;
    exit;
  end;

  { Start a new block or continue the current one. }
  if (strm.avail_in <> 0) or (s^.lookahead <> 0)
    or ((flush <> Z_NO_FLUSH) and (s^.status <> FINISH_STATE)) then
  begin
    bstate := configuration_table[s^.level].func(s^, flush);

    if (bstate = finish_started) or (bstate = finish_done) then
      s^.status := FINISH_STATE;

    if (bstate = need_more) or (bstate = finish_started) then
    begin
      if (strm.avail_out = 0) then
        s^.last_flush := -1; { avoid BUF_ERROR next call, see above }

      deflate := Z_OK;
      exit;
      { If flush != Z_NO_FLUSH && avail_out == 0, the next call
	of deflate should use the same flush parameter to make sure
	that the flush is complete. So we don't have to output an
	empty block here, this will be done at next call. This also
	ensures that for a very small output buffer, we emit at most
	 one empty block. }
    end;
    if (bstate = block_done) then
    begin
      if (flush = Z_PARTIAL_FLUSH) then
        _tr_align(s^)
      else
      begin  { FULL_FLUSH or SYNC_FLUSH }
        _tr_stored_block(s^, pcharf(NIL), Long(0), FALSE);
        { For a full flush, this empty block will be recognized
          as a special marker by inflate_sync(). }

        if (flush = Z_FULL_FLUSH) then
        begin
          {macro CLEAR_HASH(s);}             { forget history }
          s^.head^[s^.hash_size-1] := ZNIL;
          zmemzero(pBytef(s^.head), unsigned(s^.hash_size-1)*sizeof(s^.head^[0]));
        end;
      end;

      flush_pending(strm);
      if (strm.avail_out = 0) then
      begin
        s^.last_flush := -1; { avoid BUF_ERROR at next call, see above }
	deflate := Z_OK;
        exit;
      end;

    end;
  end;
  {$IFDEF DEBUG}
  Assert(strm.avail_out > 0, 'bug2');
  {$ENDIF}
  if (flush <> Z_FINISH) then
  begin
    deflate := Z_OK;
    exit;
  end;

  if (s^.noheader <> 0) then
  begin
    deflate := Z_STREAM_END;
    exit;
  end;

  { Write the zlib trailer (adler32) }
  putShortMSB(s^, uInt(strm.adler shr 16));
  putShortMSB(s^, uInt(strm.adler and $ffff));
  flush_pending(strm);
  { If avail_out is zero, the application will call deflate again
    to flush the rest. }

  s^.noheader := -1; { write the trailer only once! }
  if s^.pending <> 0 then
    deflate := Z_OK
  else
    deflate := Z_STREAM_END;
end;

{ ========================================================================= }
function deflateEnd (var strm : z_stream) : int;
var
  status : int;
  s : deflate_state_ptr;
begin
  if {(@strm = Z_NULL) or} (strm.state = Z_NULL) then
  begin
    deflateEnd := Z_STREAM_ERROR;
    exit;
  end;

  s := deflate_state_ptr(strm.state);
  status := s^.status;
  if (status <> INIT_STATE) and (status <> BUSY_STATE) and
     (status <> FINISH_STATE) then
  begin
    deflateEnd := Z_STREAM_ERROR;
    exit;
  end;

  { Deallocate in reverse order of allocations: }
  TRY_FREE(strm, s^.pending_buf);
  TRY_FREE(strm, s^.head);
  TRY_FREE(strm, s^.prev);
  TRY_FREE(strm, s^.window);

  ZFREE(strm, s);
  strm.state := Z_NULL;

  if status = BUSY_STATE then
    deflateEnd := Z_DATA_ERROR
  else
    deflateEnd := Z_OK;
end;

{ =========================================================================
  Copy the source state to the destination state.
  To simplify the source, this is not supported for 16-bit MSDOS (which
  doesn't have enough memory anyway to duplicate compression states). }


{ ========================================================================= }
function deflateCopy (dest, source : z_streamp) : int;
{$ifndef MAXSEG_64K}
var
  ds : deflate_state_ptr;
  ss : deflate_state_ptr;
  overlay : pushfArray;
{$endif}
begin
{$ifdef MAXSEG_64K}
  deflateCopy := Z_STREAM_ERROR;
  exit;
{$else}

  if (source = Z_NULL) or (dest = Z_NULL) or (source^.state = Z_NULL) then
  begin
    deflateCopy := Z_STREAM_ERROR;
    exit;
  end;
  ss := deflate_state_ptr(source^.state);
  dest^ := source^;

  ds := deflate_state_ptr( ZALLOC(dest^, 1, sizeof(deflate_state)) );
  if (ds = Z_NULL) then
  begin
    deflateCopy := Z_MEM_ERROR;
    exit;
  end;