example.pas

本代码为LZW算法的C语言实现程序

  err := deflate(c_stream, Z_NO_FLUSH);
  CHECK_ERR(err, 'deflate');

  (* Switch back to compressing mode: *)
  deflateParams(c_stream, Z_BEST_COMPRESSION, Z_FILTERED);
  c_stream.next_in := uncompr;
  c_stream.avail_in := Integer(uncomprLen);
  err := deflate(c_stream, Z_NO_FLUSH);
  CHECK_ERR(err, 'deflate');

  err := deflate(c_stream, Z_FINISH);
  if err <> Z_STREAM_END then
    EXIT_ERR('deflate should report Z_STREAM_END');

  err := deflateEnd(c_stream);
  CHECK_ERR(err, 'deflateEnd');
end;
{$ENDIF}

(* ===========================================================================
 * Test inflate with large buffers
 *)
{$IFDEF TEST_INFLATE}
procedure test_large_inflate(compr: Pointer; comprLen: LongInt;
                             uncompr: Pointer; uncomprLen: LongInt);
var err: Integer;
    d_stream: z_stream; (* decompression stream *)
begin
  StrCopy(PChar(uncompr), 'garbage');

  d_stream.zalloc := NIL;
  d_stream.zfree := NIL;
  d_stream.opaque := NIL;

  d_stream.next_in := compr;
  d_stream.avail_in := Integer(comprLen);

  err := inflateInit(d_stream);
  CHECK_ERR(err, 'inflateInit');

  while TRUE do
  begin
    d_stream.next_out := uncompr;            (* discard the output *)
    d_stream.avail_out := Integer(uncomprLen);
    err := inflate(d_stream, Z_NO_FLUSH);
    if err = Z_STREAM_END then
      break;
    CHECK_ERR(err, 'large inflate');
  end;

  err := inflateEnd(d_stream);
  CHECK_ERR(err, 'inflateEnd');

  if d_stream.total_out <> 2 * uncomprLen + comprLen div 2 then
  begin
    WriteLn('bad large inflate: ', d_stream.total_out);
    Halt(1);
  end
  else
    WriteLn('large_inflate(): OK');
end;
{$ENDIF}

(* ===========================================================================
 * Test deflate with full flush
 *)
{$IFDEF TEST_FLUSH}
procedure test_flush(compr: Pointer; var comprLen : LongInt);
var c_stream: z_stream; (* compression stream *)
    err: Integer;
    len: Integer;
begin
  len := StrLen(hello)+1;

  c_stream.zalloc := NIL;
  c_stream.zfree := NIL;
  c_stream.opaque := NIL;

  err := deflateInit(c_stream, Z_DEFAULT_COMPRESSION);
  CHECK_ERR(err, 'deflateInit');

  c_stream.next_in := hello;
  c_stream.next_out := compr;
  c_stream.avail_in := 3;
  c_stream.avail_out := Integer(comprLen);
  err := deflate(c_stream, Z_FULL_FLUSH);
  CHECK_ERR(err, 'deflate');

  Inc(PByteArray(compr)^[3]); (* force an error in first compressed block *)
  c_stream.avail_in := len - 3;

  err := deflate(c_stream, Z_FINISH);
  if err <> Z_STREAM_END then
    CHECK_ERR(err, 'deflate');

  err := deflateEnd(c_stream);
  CHECK_ERR(err, 'deflateEnd');

  comprLen := c_stream.total_out;
end;
{$ENDIF}

(* ===========================================================================
 * Test inflateSync()
 *)
{$IFDEF TEST_SYNC}
procedure test_sync(compr: Pointer; comprLen: LongInt;
                    uncompr: Pointer; uncomprLen : LongInt);
var err: Integer;
    d_stream: z_stream; (* decompression stream *)
begin
  StrCopy(PChar(uncompr), 'garbage');

  d_stream.zalloc := NIL;
  d_stream.zfree := NIL;
  d_stream.opaque := NIL;

  d_stream.next_in := compr;
  d_stream.avail_in := 2; (* just read the zlib header *)

  err := inflateInit(d_stream);
  CHECK_ERR(err, 'inflateInit');

  d_stream.next_out := uncompr;
  d_stream.avail_out := Integer(uncomprLen);

  inflate(d_stream, Z_NO_FLUSH);
  CHECK_ERR(err, 'inflate');

  d_stream.avail_in := Integer(comprLen-2);   (* read all compressed data *)
  err := inflateSync(d_stream);               (* but skip the damaged part *)
  CHECK_ERR(err, 'inflateSync');

  err := inflate(d_stream, Z_FINISH);
  if err <> Z_DATA_ERROR then
    EXIT_ERR('inflate should report DATA_ERROR');
    (* Because of incorrect adler32 *)

  err := inflateEnd(d_stream);
  CHECK_ERR(err, 'inflateEnd');

  WriteLn('after inflateSync(): hel', PChar(uncompr));
end;
{$ENDIF}

(* ===========================================================================
 * Test deflate with preset dictionary
 *)
{$IFDEF TEST_DICT}
procedure test_dict_deflate(compr: Pointer; comprLen: LongInt);
var c_stream: z_stream; (* compression stream *)
    err: Integer;
begin
  c_stream.zalloc := NIL;
  c_stream.zfree := NIL;
  c_stream.opaque := NIL;

  err := deflateInit(c_stream, Z_BEST_COMPRESSION);
  CHECK_ERR(err, 'deflateInit');

  err := deflateSetDictionary(c_stream, dictionary, StrLen(dictionary));
  CHECK_ERR(err, 'deflateSetDictionary');

  dictId := c_stream.adler;
  c_stream.next_out := compr;
  c_stream.avail_out := Integer(comprLen);

  c_stream.next_in := hello;
  c_stream.avail_in := StrLen(hello)+1;

  err := deflate(c_stream, Z_FINISH);
  if err <> Z_STREAM_END then
    EXIT_ERR('deflate should report Z_STREAM_END');

  err := deflateEnd(c_stream);
  CHECK_ERR(err, 'deflateEnd');
end;
{$ENDIF}

(* ===========================================================================
 * Test inflate with a preset dictionary
 *)
{$IFDEF TEST_DICT}
procedure test_dict_inflate(compr: Pointer; comprLen: LongInt;
                            uncompr: Pointer; uncomprLen: LongInt);
var err: Integer;
    d_stream: z_stream; (* decompression stream *)
begin
  StrCopy(PChar(uncompr), 'garbage');

  d_stream.zalloc := NIL;
  d_stream.zfree := NIL;
  d_stream.opaque := NIL;

  d_stream.next_in := compr;
  d_stream.avail_in := Integer(comprLen);

  err := inflateInit(d_stream);
  CHECK_ERR(err, 'inflateInit');

  d_stream.next_out := uncompr;
  d_stream.avail_out := Integer(uncomprLen);

  while TRUE do
  begin
    err := inflate(d_stream, Z_NO_FLUSH);
    if err = Z_STREAM_END then
      break;
    if err = Z_NEED_DICT then
    begin
      if d_stream.adler <> dictId then
        EXIT_ERR('unexpected dictionary');
      err := inflateSetDictionary(d_stream, dictionary, StrLen(dictionary));
    end;
    CHECK_ERR(err, 'inflate with dict');
  end;

  err := inflateEnd(d_stream);
  CHECK_ERR(err, 'inflateEnd');

  if StrComp(PChar(uncompr), hello) <> 0 then
    EXIT_ERR('bad inflate with dict')
  else
    WriteLn('inflate with dictionary: ', PChar(uncompr));
end;
{$ENDIF}

var compr, uncompr: Pointer;
    comprLen, uncomprLen: LongInt;

begin
  if zlibVersion^ <> ZLIB_VERSION[1] then
    EXIT_ERR('Incompatible zlib version');

  WriteLn('zlib version: ', zlibVersion);
  WriteLn('zlib compile flags: ', Format('0x%x', [zlibCompileFlags]));

  comprLen := 10000 * SizeOf(Integer); (* don't overflow on MSDOS *)
  uncomprLen := comprLen;
  GetMem(compr, comprLen);
  GetMem(uncompr, uncomprLen);
  if (compr = NIL) or (uncompr = NIL) then
    EXIT_ERR('Out of memory');
  (* compr and uncompr are cleared to avoid reading uninitialized
   * data and to ensure that uncompr compresses well.
   *)
  FillChar(compr^, comprLen, 0);
  FillChar(uncompr^, uncomprLen, 0);

  {$IFDEF TEST_COMPRESS}
  WriteLn('** Testing compress');
  test_compress(compr, comprLen, uncompr, uncomprLen);
  {$ENDIF}

  {$IFDEF TEST_GZIO}
  WriteLn('** Testing gzio');
  if ParamCount >= 1 then
    test_gzio(ParamStr(1), uncompr, uncomprLen)
  else
    test_gzio(TESTFILE, uncompr, uncomprLen);
  {$ENDIF}

  {$IFDEF TEST_DEFLATE}
  WriteLn('** Testing deflate with small buffers');
  test_deflate(compr, comprLen);
  {$ENDIF}
  {$IFDEF TEST_INFLATE}
  WriteLn('** Testing inflate with small buffers');
  test_inflate(compr, comprLen, uncompr, uncomprLen);
  {$ENDIF}

  {$IFDEF TEST_DEFLATE}
  WriteLn('** Testing deflate with large buffers');
  test_large_deflate(compr, comprLen, uncompr, uncomprLen);
  {$ENDIF}
  {$IFDEF TEST_INFLATE}
  WriteLn('** Testing inflate with large buffers');
  test_large_inflate(compr, comprLen, uncompr, uncomprLen);
  {$ENDIF}

  {$IFDEF TEST_FLUSH}
  WriteLn('** Testing deflate with full flush');
  test_flush(compr, comprLen);
  {$ENDIF}
  {$IFDEF TEST_SYNC}
  WriteLn('** Testing inflateSync');
  test_sync(compr, comprLen, uncompr, uncomprLen);
  {$ENDIF}
  comprLen := uncomprLen;

  {$IFDEF TEST_DICT}
  WriteLn('** Testing deflate and inflate with preset dictionary');
  test_dict_deflate(compr, comprLen);
  test_dict_inflate(compr, comprLen, uncompr, uncomprLen);
  {$ENDIF}

  FreeMem(compr, comprLen);
  FreeMem(uncompr, uncomprLen);
end.