vs_compress.pas

KSDev.VirtualSream.v1.01.rar 虚拟文件系统,

                        { Advanced functions }

{ The following functions are needed only in some special applications. }


{EXPORT}
function deflateInit2 (var strm : z_stream;
                       level : int;
                       method : int;
                       windowBits : int;
                       memLevel : int;
                       strategy : int) : int;

{  This is another version of deflateInit with more compression options. The
   fields next_in, zalloc, zfree and opaque must be initialized before by
   the caller.

     The method parameter is the compression method. It must be Z_DEFLATED in
   this version of the library. (Method 9 will allow a 64K history buffer and
   partial block flushes.)

     The windowBits parameter is the base two logarithm of the window size
   (the size of the history buffer).  It should be in the range 8..15 for this
   version of the library (the value 16 will be allowed for method 9). Larger
   values of this parameter result in better compression at the expense of
   memory usage. The default value is 15 if deflateInit is used instead.

     The memLevel parameter specifies how much memory should be allocated
   for the internal compression state. memLevel=1 uses minimum memory but
   is slow and reduces compression ratio; memLevel=9 uses maximum memory
   for optimal speed. The default value is 8. See zconf.h for total memory
   usage as a function of windowBits and memLevel.

     The strategy parameter is used to tune the compression algorithm. Use the
   value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
   filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
   string match).  Filtered data consists mostly of small values with a
   somewhat random distribution. In this case, the compression algorithm is
   tuned to compress them better. The effect of Z_FILTERED is to force more
   Huffman coding and less string matching; it is somewhat intermediate
   between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
   the compression ratio but not the correctness of the compressed output even
   if it is not set appropriately.

     If next_in is not null, the library will use this buffer to hold also
   some history information; the buffer must either hold the entire input
   data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
   is null, the library will allocate its own history buffer (and leave next_in
   null). next_out need not be provided here but must be provided by the
   application for the next call of deflate().

     If the history buffer is provided by the application, next_in must
   must never be changed by the application since the compressor maintains
   information inside this buffer from call to call; the application
   must provide more input only by increasing avail_in. next_in is always
   reset by the library in this case.

      deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
   not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
   an invalid method). msg is set to null if there is no error message.
   deflateInit2 does not perform any compression: this will be done by
   deflate(). }


{EXPORT}
function deflateSetDictionary (var strm : z_stream;
                               dictionary : pBytef; 
			       dictLength : uint) : int;

{    Initializes the compression dictionary (history buffer) from the given
   byte sequence without producing any compressed output. This function must
   be called immediately after deflateInit or deflateInit2, before any call
   of deflate. The compressor and decompressor must use exactly the same
   dictionary (see inflateSetDictionary).
     The dictionary should consist of strings (byte sequences) that are likely
   to be encountered later in the data to be compressed, with the most commonly
   used strings preferably put towards the end of the dictionary. Using a
   dictionary is most useful when the data to be compressed is short and
   can be predicted with good accuracy; the data can then be compressed better
   than with the default empty dictionary. In this version of the library,
   only the last 32K bytes of the dictionary are used.
     Upon return of this function, strm->adler is set to the Adler32 value
   of the dictionary; the decompressor may later use this value to determine
   which dictionary has been used by the compressor. (The Adler32 value
   applies to the whole dictionary even if only a subset of the dictionary is
   actually used by the compressor.)

     deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
   parameter is invalid (such as NULL dictionary) or the stream state
   is inconsistent (for example if deflate has already been called for this
   stream). deflateSetDictionary does not perform any compression: this will
   be done by deflate(). }

{EXPORT}
function deflateCopy (dest : z_streamp;
                      source : z_streamp) : int;

{  Sets the destination stream as a complete copy of the source stream.  If
   the source stream is using an application-supplied history buffer, a new
   buffer is allocated for the destination stream.  The compressed output
   buffer is always application-supplied. It's the responsibility of the
   application to provide the correct values of next_out and avail_out for the
   next call of deflate.

     This function can be useful when several compression strategies will be
   tried, for example when there are several ways of pre-processing the input
   data with a filter. The streams that will be discarded should then be freed
   by calling deflateEnd.  Note that deflateCopy duplicates the internal
   compression state which can be quite large, so this strategy is slow and
   can consume lots of memory.

     deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
   enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
   (such as zalloc being NULL). msg is left unchanged in both source and
   destination. }

{EXPORT}
function deflateReset (var strm : z_stream) : int;

{   This function is equivalent to deflateEnd followed by deflateInit,
   but does not free and reallocate all the internal compression state.
   The stream will keep the same compression level and any other attributes
   that may have been set by deflateInit2.

      deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
   stream state was inconsistent (such as zalloc or state being NIL). }


{EXPORT}
function deflateParams (var strm : z_stream; level : int; strategy : int) : int;

{    Dynamically update the compression level and compression strategy.
   This can be used to switch between compression and straight copy of
   the input data, or to switch to a different kind of input data requiring
   a different strategy. If the compression level is changed, the input
   available so far is compressed with the old level (and may be flushed);
   the new level will take effect only at the next call of deflate().

     Before the call of deflateParams, the stream state must be set as for
   a call of deflate(), since the currently available input may have to
   be compressed and flushed. In particular, strm->avail_out must be non-zero.

     deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
   stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
   if strm->avail_out was zero. }


const
   deflate_copyright : string = ' deflate 1.1.2 Copyright 1995-1998 Jean-loup Gailly ';

{ If you use the zlib library in a product, an acknowledgment is welcome
  in the documentation of your product. If for some reason you cannot
  include such an acknowledgment, I would appreciate that you keep this
  copyright string in the executable of your product. }


{ZKsInfBlock}
function inflate_blocks_new(var z : z_stream;
                            c : check_func; 
                            w : uInt    
                            ) : pInflate_blocks_state;

function inflate_blocks (var s : inflate_blocks_state;
                         var z : z_stream;
                         r : int            
                         ) : int;

procedure inflate_blocks_reset (var s : inflate_blocks_state;
                                var z : z_stream;
                                c : puLong); 


function inflate_blocks_free(s : pInflate_blocks_state;
                             var z : z_stream) : int;

procedure inflate_set_dictionary(var s : inflate_blocks_state;
                                 const d : array of byte;  
                                 n : uInt);        

function inflate_blocks_sync_point(var s : inflate_blocks_state) : int;


{ZKsInfCodes}
function inflate_codes_new (bl : uInt;
                            bd : uInt;
                            tl : pInflate_huft;
                            td : pInflate_huft;
                            var z : z_stream): pInflate_codes_state;

function inflate_codes(var s : inflate_blocks_state;
                       var z : z_stream;
                       r : int) : int;

procedure inflate_codes_free(c : pInflate_codes_state;
                             var z : z_stream);


{ZKsInFast}
function inflate_fast( bl : uInt;
                       bd : uInt;
                       tl : pInflate_huft;
                       td : pInflate_huft;
                      var s : inflate_blocks_state;
                      var z : z_stream) : int;

{ZKsInflate}
function inflateInit(var z : z_stream) : int;

{    Initializes the internal stream state for decompression. The fields
   zalloc, zfree and opaque must be initialized before by the caller.  If
   zalloc and zfree are set to Z_NULL, inflateInit updates them to use default
   allocation functions.

     inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
   enough memory, Z_VERSION_ERROR if the zlib library version is incompatible
   with the version assumed by the caller.  msg is set to null if there is no
   error message. inflateInit does not perform any decompression: this will be
   done by inflate(). }



function inflateInit_(z : z_streamp;
                      const version : string;
                      stream_size : int) : int;


function inflateInit2_(var z: z_stream;
                       w : int;
                       const version : string;
                       stream_size : int) : int;
{
     This is another version of inflateInit with an extra parameter. The
   fields next_in, avail_in, zalloc, zfree and opaque must be initialized
   before by the caller.

     The windowBits parameter is the base two logarithm of the maximum window
   size (the size of the history buffer).  It should be in the range 8..15 for
   this version of the library. The default value is 15 if inflateInit is used
   instead. If a compressed stream with a larger window size is given as
   input, inflate() will return with the error code Z_DATA_ERROR instead of
   trying to allocate a larger window.

      inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
   memory, Z_STREAM_ERROR if a parameter is invalid (such as a negative
   memLevel). msg is set to null if there is no error message.  inflateInit2
   does not perform any decompression apart from reading the zlib header if
   present: this will be done by inflate(). (So next_in and avail_in may be
   modified, but next_out and avail_out are unchanged.)
}



function inflateEnd(var z : z_stream) : int;

{
   All dynamically allocated data structures for this stream are freed.
   This function discards any unprocessed input and does not flush any
   pending output.

     inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
   was inconsistent. In the error case, msg may be set but then points to a
   static string (which must not be deallocated).
}

function inflateReset(var z : z_stream) : int;

{
   This function is equivalent to inflateEnd followed by inflateInit,
   but does not free and reallocate all the internal decompression state.
   The stream will keep attributes that may have been set by inflateInit2.

      inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
   stream state was inconsistent (such as zalloc or state being NULL).
}


function inflate(var z : z_stream;
                 f : int) : int;
{
  inflate decompresses as much data as possible, and stops when the input
  buffer becomes empty or the output buffer becomes full. It may introduce
  some output latency (reading input without producing any output)
  except when forced to flush.

  The detailed semantics are as follows. inflate performs one or both of the
  following actions:

  - Decompress more input starting at next_in and update next_in and avail_in
    accordingly. If not all input can be processed (because there is not
    enough room in the output buffer), next_in is updated and processing
    will resume at this point for the next call of inflate().

  - Provide more output starting at next_out and update next_out and avail_out
    accordingly.  inflate() provides as much output as possible, until there
    is no more input data or no more space in the output buffer (see below
    about the flush parameter).

  Before the call of inflate(), the application should ensure that at least
  one of the actions is possible, by providing more input and/or consuming
  more output, and updating the next_* and avail_* values accordingly.
  The application can consume the uncompressed output when it wants, for
  example when the output buffer is full (avail_out == 0), or after each
  call of inflate(). If inflate returns Z_OK and with zero avail_out, it
  must be called again after making room in the output buffer because there
  might be more output pending.

    If the parameter flush is set to Z_SYNC_FLUSH, inflate flushes as much
  output as possible to the output buffer. The flushing behavior of inflate is
  not specified for values of the flush parameter other than Z_SYNC_FLUSH
  and Z_FINISH, but the current implement actually flushes as much output
  as possible anyway.

    inflate() should normally be called until it returns Z_STREAM_END or an
  error. However if all decompression is to be performed in a single step
  (a single call of inflate), the parameter flush should be set to
  Z_FINISH. In this case all pending input is processed and all pending
  output is flushed; avail_out must be large enough to hold all the
  uncompressed data. (The size of the uncompressed data may have been saved
  by the compressor for this purpose.) The next operation on this stream must
  be inflateEnd to deallocate the decompression state. The use of Z_FINISH
  is never required, but can be used to inform inflate that a faster routine
  may be used for the single inflate() call.

     If a preset dictionary is needed at this point (see inflateSetDictionary
  below), inflate sets strm-adler to the adler32 checksum of the
  dictionary chosen by the compressor and returns Z_NEED_DICT; otherwise 
  it sets strm->adler to the adler32 checksum of all output produced
  so far (that is, total_out bytes) and returns Z_OK, Z_STREAM_END or
  an error code as described below. At the end of the stream, inflate()
  checks that its computed adler32 checksum is equal to that saved by the
  compressor and returns Z_STREAM_END only if the checksum is correct.

    inflate() returns Z_OK if some progress has been made (more input processed
  or more output produced), Z_STREAM_END if the end of the compressed data has
  been reached and all uncompressed output has been produced, Z_NEED_DICT if a
  preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
  corrupted (input stream not conforming to the zlib format or incorrect
  adler32 checksum), Z_STREAM_ERROR if the stream structure was inconsistent
  (for example if next_in or next_out was NULL), Z_MEM_ERROR if there was not
  enough memory, Z_BUF_ERROR if no progress is possible or if there was not
  enough room in the output buffer when Z_FINISH is used. In the Z_DATA_ERROR
  case, the application may then call inflateSync to look for a good
  compression block.
}


function inflateSetDictionary(var z : z_stream;