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Merged common/gzip-stream.* and common/zlib.*

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svn-id: r34578
This commit is contained in:
Max Horn 2008-09-16 11:50:10 +00:00
parent 6a4d96649e
commit f3dfb5ebab
6 changed files with 329 additions and 401 deletions
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2
backends/saves/compressed/compressed-saves.cpp
View file

@ -23,7 +23,7 @@
* *
*/ */
#include "common/gzip-stream.h" #include "common/zlib.h"
#include "backends/saves/compressed/compressed-saves.h" #include "backends/saves/compressed/compressed-saves.h"

327
common/gzip-stream.cpp
View file

@ -1,327 +0,0 @@
/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#include "common/gzip-stream.h"
#include "common/util.h"
#if defined(USE_ZLIB)
#include <zlib.h>
#if ZLIB_VERNUM < 0x1204
#error Version 1.2.0.4 or newer of zlib is required for this code
#endif
#endif
namespace Common {
#if defined(USE_ZLIB)
/**
* A simple wrapper class which can be used to wrap around an arbitrary
* other SeekableReadStream and will then provide on-the-fly decompression support.
* Assumes the compressed data to be in gzip format.
*/
class GZipReadStream : public Common::SeekableReadStream {
protected:
enum {
BUFSIZE = 16384 // 1 << MAX_WBITS
};
byte _buf[BUFSIZE];
Common::SeekableReadStream *_wrapped;
z_stream _stream;
int _zlibErr;
uint32 _pos;
uint32 _origSize;
bool _eos;
public:
GZipReadStream(Common::SeekableReadStream *w) : _wrapped(w) {
assert(w != 0);
_stream.zalloc = Z_NULL;
_stream.zfree = Z_NULL;
_stream.opaque = Z_NULL;
// Verify file header is correct
w->seek(0, SEEK_SET);
uint16 header = w->readUint16BE();
assert(header == 0x1F8B ||
((header & 0x0F00) == 0x0800 && header % 31 == 0));
if (header == 0x1F8B) {
// Retrieve the original file size
w->seek(-4, SEEK_END);
_origSize = w->readUint32LE();
} else {
// Original size not available in zlib format
_origSize = 0;
}
_pos = 0;
w->seek(0, SEEK_SET);
_eos = false;
// Adding 32 to windowBits indicates to zlib that it is supposed to
// automatically detect whether gzip or zlib headers are used for
// the compressed file. This feature was added in zlib 1.2.0.4,
// released 10 August 2003.
// Note: This is *crucial* for savegame compatibility, do *not* remove!
_zlibErr = inflateInit2(&_stream, MAX_WBITS + 32);
if (_zlibErr != Z_OK)
return;
// Setup input buffer
_stream.next_in = _buf;
_stream.avail_in = 0;
}
~GZipReadStream() {
inflateEnd(&_stream);
delete _wrapped;
}
bool err() const { return (_zlibErr != Z_OK) && (_zlibErr != Z_STREAM_END); }
void clearErr() {
// only reset _eos; I/O errors are not recoverable
_eos = false;
}
uint32 read(void *dataPtr, uint32 dataSize) {
_stream.next_out = (byte *)dataPtr;
_stream.avail_out = dataSize;
// Keep going while we get no error
while (_zlibErr == Z_OK && _stream.avail_out) {
if (_stream.avail_in == 0 && !_wrapped->eos()) {
// If we are out of input data: Read more data, if available.
_stream.next_in = _buf;
_stream.avail_in = _wrapped->read(_buf, BUFSIZE);
}
_zlibErr = inflate(&_stream, Z_NO_FLUSH);
}
// Update the position counter
_pos += dataSize - _stream.avail_out;
if (_zlibErr == Z_STREAM_END && _stream.avail_out > 0)
_eos = true;
return dataSize - _stream.avail_out;
}
bool eos() const {
return _eos;
}
int32 pos() const {
return _pos;
}
int32 size() const {
return _origSize;
}
bool seek(int32 offset, int whence = SEEK_SET) {
int32 newPos = 0;
assert(whence != SEEK_END); // SEEK_END not supported
switch(whence) {
case SEEK_SET:
newPos = offset;
break;
case SEEK_CUR:
newPos = _pos + offset;
}
assert(newPos >= 0);
if ((uint32)newPos < _pos) {
// To search backward, we have to restart the whole decompression
// from the start of the file. A rather wasteful operation, best
// to avoid it. :/
#if DEBUG
warning("Backward seeking in GZipReadStream detected");
#endif
_pos = 0;
_wrapped->seek(0, SEEK_SET);
_zlibErr = inflateReset(&_stream);
if (_zlibErr != Z_OK)
return false; // FIXME: STREAM REWRITE
_stream.next_in = _buf;
_stream.avail_in = 0;
}
offset = newPos - _pos;
// Skip the given amount of data (very inefficient if one tries to skip
// huge amounts of data, but usually client code will only skip a few
// bytes, so this should be fine.
byte tmpBuf[1024];
while (!err() && offset > 0) {
offset -= read(tmpBuf, MIN((int32)sizeof(tmpBuf), offset));
}
_eos = false;
return true; // FIXME: STREAM REWRITE
}
};
/**
* A simple wrapper class which can be used to wrap around an arbitrary
* other WriteStream and will then provide on-the-fly compression support.
* The compressed data is written in the gzip format.
*/
class GZipWriteStream : public Common::WriteStream {
protected:
enum {
BUFSIZE = 16384 // 1 << MAX_WBITS
};
byte _buf[BUFSIZE];
Common::WriteStream *_wrapped;
z_stream _stream;
int _zlibErr;
void processData(int flushType) {
// This function is called by both write() and finalize().
while (_zlibErr == Z_OK && (_stream.avail_in || flushType == Z_FINISH)) {
if (_stream.avail_out == 0) {
if (_wrapped->write(_buf, BUFSIZE) != BUFSIZE) {
_zlibErr = Z_ERRNO;
break;
}
_stream.next_out = _buf;
_stream.avail_out = BUFSIZE;
}
_zlibErr = deflate(&_stream, flushType);
}
}
public:
GZipWriteStream(Common::WriteStream *w) : _wrapped(w) {
assert(w != 0);
_stream.zalloc = Z_NULL;
_stream.zfree = Z_NULL;
_stream.opaque = Z_NULL;
// Adding 16 to windowBits indicates to zlib that it is supposed to
// write gzip headers. This feature was added in zlib 1.2.0.4,
// released 10 August 2003.
// Note: This is *crucial* for savegame compatibility, do *not* remove!
_zlibErr = deflateInit2(&_stream,
Z_DEFAULT_COMPRESSION,
Z_DEFLATED,
MAX_WBITS + 16,
8,
Z_DEFAULT_STRATEGY);
assert(_zlibErr == Z_OK);
_stream.next_out = _buf;
_stream.avail_out = BUFSIZE;
_stream.avail_in = 0;
_stream.next_in = 0;
}
~GZipWriteStream() {
finalize();
deflateEnd(&_stream);
delete _wrapped;
}
bool err() const {
// CHECKME: does Z_STREAM_END make sense here?
return (_zlibErr != Z_OK && _zlibErr != Z_STREAM_END) || _wrapped->err();
}
void clearErr() {
// Note: we don't reset the _zlibErr here, as it is not
// clear in general how
_wrapped->clearErr();
}
void finalize() {
if (_zlibErr != Z_OK)
return;
// Process whatever remaining data there is.
processData(Z_FINISH);
// Since processData only writes out blocks of size BUFSIZE,
// we may have to flush some stragglers.
uint remainder = BUFSIZE - _stream.avail_out;
if (remainder > 0) {
if (_wrapped->write(_buf, remainder) != remainder) {
_zlibErr = Z_ERRNO;
}
}
// Finalize the wrapped savefile, too
_wrapped->finalize();
}
uint32 write(const void *dataPtr, uint32 dataSize) {
if (err())
return 0;
// Hook in the new data ...
// Note: We need to make a const_cast here, as zlib is not aware
// of the const keyword.
_stream.next_in = const_cast<byte *>((const byte *)dataPtr);
_stream.avail_in = dataSize;
// ... and flush it to disk
processData(Z_NO_FLUSH);
return dataSize - _stream.avail_in;
}
};
#endif // USE_ZLIB
Common::SeekableReadStream *wrapCompressedReadStream(Common::SeekableReadStream *toBeWrapped) {
#if defined(USE_ZLIB)
if (toBeWrapped) {
uint16 header = toBeWrapped->readUint16BE();
bool isCompressed = (header == 0x1F8B ||
((header & 0x0F00) == 0x0800 &&
header % 31 == 0));
toBeWrapped->seek(-2, SEEK_CUR);
if (isCompressed)
return new GZipReadStream(toBeWrapped);
}
#endif
return toBeWrapped;
}
Common::WriteStream *wrapCompressedWriteStream(Common::WriteStream *toBeWrapped) {
#if defined(USE_ZLIB)
if (toBeWrapped)
return new GZipWriteStream(toBeWrapped);
#endif
return toBeWrapped;
}
} // End of namespace Common

58
common/gzip-stream.h
View file

@ -1,58 +0,0 @@
/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#ifndef COMMON_GZIP_STREAM_H
#define COMMON_GZIP_STREAM_H
#include "common/stream.h"
namespace Common {
/**
* Take an arbitrary SeekableReadStream and wrap it in a custom stream which
* provides transparent on-the-fly decompression. Assumes the data it
* retrieves from the wrapped stream to be either uncompressed or in gzip
* format. In the former case, the original stream is returned unmodified
* (and in particular, not wrapped).
*
* It is safe to call this with a NULL parameter (in this case, NULL is
* returned).
*/
Common::SeekableReadStream *wrapCompressedReadStream(Common::SeekableReadStream *toBeWrapped);
/**
* Take an arbitrary WriteStream and wrap it in a custom stream which provides
* transparent on-the-fly compression. The compressed data is written in the
* gzip format, unless ZLIB support has been disabled, in which case the given
* stream is returned unmodified (and in particular, not wrapped).
*
* It is safe to call this with a NULL parameter (in this case, NULL is
* returned).
*/
Common::WriteStream *wrapCompressedWriteStream(Common::WriteStream *toBeWrapped);
} // End of namespace Common
#endif

1
common/module.mk
View file

@ -7,7 +7,6 @@ MODULE_OBJS := \
config-manager.o \ config-manager.o \
file.o \ file.o \
fs.o \ fs.o \
gzip-stream.o \
hashmap.o \ hashmap.o \
memorypool.o \ memorypool.o \
md5.o \ md5.o \

304
common/zlib.cpp
View file

@ -8,37 +8,327 @@
* modify it under the terms of the GNU General Public License * modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2 * as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version. * of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, * This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of * but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details. * GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License * You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software * along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* *
* $URL$ * $URL$
* $Id$ * $Id$
*
*/ */
#include "common/zlib.h" #include "common/zlib.h"
#include "common/util.h"
#if defined(USE_ZLIB) #if defined(USE_ZLIB)
#ifdef __SYMBIAN32__
#include <zlib\zlib.h>
#else
#include <zlib.h>
#endif
#ifdef __SYMBIAN32__ #if ZLIB_VERNUM < 0x1204
#include <zlib\zlib.h> #error Version 1.2.0.4 or newer of zlib is required for this code
#else #endif
#include <zlib.h>
#endif #endif
namespace Common { namespace Common {
#if defined(USE_ZLIB)
bool uncompress(byte *dst, unsigned long *dstLen, const byte *src, unsigned long srcLen) { bool uncompress(byte *dst, unsigned long *dstLen, const byte *src, unsigned long srcLen) {
return Z_OK == ::uncompress(dst, dstLen, src, srcLen); return Z_OK == ::uncompress(dst, dstLen, src, srcLen);
} }
} // end of namespace Common /**
* A simple wrapper class which can be used to wrap around an arbitrary
* other SeekableReadStream and will then provide on-the-fly decompression support.
* Assumes the compressed data to be in gzip format.
*/
class GZipReadStream : public Common::SeekableReadStream {
protected:
enum {
BUFSIZE = 16384 // 1 << MAX_WBITS
};
byte _buf[BUFSIZE];
Common::SeekableReadStream *_wrapped;
z_stream _stream;
int _zlibErr;
uint32 _pos;
uint32 _origSize;
bool _eos;
public:
GZipReadStream(Common::SeekableReadStream *w) : _wrapped(w) {
assert(w != 0);
_stream.zalloc = Z_NULL;
_stream.zfree = Z_NULL;
_stream.opaque = Z_NULL;
// Verify file header is correct
w->seek(0, SEEK_SET);
uint16 header = w->readUint16BE();
assert(header == 0x1F8B ||
((header & 0x0F00) == 0x0800 && header % 31 == 0));
if (header == 0x1F8B) {
// Retrieve the original file size
w->seek(-4, SEEK_END);
_origSize = w->readUint32LE();
} else {
// Original size not available in zlib format
_origSize = 0;
}
_pos = 0;
w->seek(0, SEEK_SET);
_eos = false;
// Adding 32 to windowBits indicates to zlib that it is supposed to
// automatically detect whether gzip or zlib headers are used for
// the compressed file. This feature was added in zlib 1.2.0.4,
// released 10 August 2003.
// Note: This is *crucial* for savegame compatibility, do *not* remove!
_zlibErr = inflateInit2(&_stream, MAX_WBITS + 32);
if (_zlibErr != Z_OK)
return;
// Setup input buffer
_stream.next_in = _buf;
_stream.avail_in = 0;
}
~GZipReadStream() {
inflateEnd(&_stream);
delete _wrapped;
}
bool err() const { return (_zlibErr != Z_OK) && (_zlibErr != Z_STREAM_END); }
void clearErr() {
// only reset _eos; I/O errors are not recoverable
_eos = false;
}
uint32 read(void *dataPtr, uint32 dataSize) {
_stream.next_out = (byte *)dataPtr;
_stream.avail_out = dataSize;
// Keep going while we get no error
while (_zlibErr == Z_OK && _stream.avail_out) {
if (_stream.avail_in == 0 && !_wrapped->eos()) {
// If we are out of input data: Read more data, if available.
_stream.next_in = _buf;
_stream.avail_in = _wrapped->read(_buf, BUFSIZE);
}
_zlibErr = inflate(&_stream, Z_NO_FLUSH);
}
// Update the position counter
_pos += dataSize - _stream.avail_out;
if (_zlibErr == Z_STREAM_END && _stream.avail_out > 0)
_eos = true;
return dataSize - _stream.avail_out;
}
bool eos() const {
return _eos;
}
int32 pos() const {
return _pos;
}
int32 size() const {
return _origSize;
}
bool seek(int32 offset, int whence = SEEK_SET) {
int32 newPos = 0;
assert(whence != SEEK_END); // SEEK_END not supported
switch(whence) {
case SEEK_SET:
newPos = offset;
break;
case SEEK_CUR:
newPos = _pos + offset;
}
assert(newPos >= 0);
if ((uint32)newPos < _pos) {
// To search backward, we have to restart the whole decompression
// from the start of the file. A rather wasteful operation, best
// to avoid it. :/
#if DEBUG
warning("Backward seeking in GZipReadStream detected");
#endif #endif
_pos = 0;
_wrapped->seek(0, SEEK_SET);
_zlibErr = inflateReset(&_stream);
if (_zlibErr != Z_OK)
return false; // FIXME: STREAM REWRITE
_stream.next_in = _buf;
_stream.avail_in = 0;
}
offset = newPos - _pos;
// Skip the given amount of data (very inefficient if one tries to skip
// huge amounts of data, but usually client code will only skip a few
// bytes, so this should be fine.
byte tmpBuf[1024];
while (!err() && offset > 0) {
offset -= read(tmpBuf, MIN((int32)sizeof(tmpBuf), offset));
}
_eos = false;
return true; // FIXME: STREAM REWRITE
}
};
/**
* A simple wrapper class which can be used to wrap around an arbitrary
* other WriteStream and will then provide on-the-fly compression support.
* The compressed data is written in the gzip format.
*/
class GZipWriteStream : public Common::WriteStream {
protected:
enum {
BUFSIZE = 16384 // 1 << MAX_WBITS
};
byte _buf[BUFSIZE];
Common::WriteStream *_wrapped;
z_stream _stream;
int _zlibErr;
void processData(int flushType) {
// This function is called by both write() and finalize().
while (_zlibErr == Z_OK && (_stream.avail_in || flushType == Z_FINISH)) {
if (_stream.avail_out == 0) {
if (_wrapped->write(_buf, BUFSIZE) != BUFSIZE) {
_zlibErr = Z_ERRNO;
break;
}
_stream.next_out = _buf;
_stream.avail_out = BUFSIZE;
}
_zlibErr = deflate(&_stream, flushType);
}
}
public:
GZipWriteStream(Common::WriteStream *w) : _wrapped(w) {
assert(w != 0);
_stream.zalloc = Z_NULL;
_stream.zfree = Z_NULL;
_stream.opaque = Z_NULL;
// Adding 16 to windowBits indicates to zlib that it is supposed to
// write gzip headers. This feature was added in zlib 1.2.0.4,
// released 10 August 2003.
// Note: This is *crucial* for savegame compatibility, do *not* remove!
_zlibErr = deflateInit2(&_stream,
Z_DEFAULT_COMPRESSION,
Z_DEFLATED,
MAX_WBITS + 16,
8,
Z_DEFAULT_STRATEGY);
assert(_zlibErr == Z_OK);
_stream.next_out = _buf;
_stream.avail_out = BUFSIZE;
_stream.avail_in = 0;
_stream.next_in = 0;
}
~GZipWriteStream() {
finalize();
deflateEnd(&_stream);
delete _wrapped;
}
bool err() const {
// CHECKME: does Z_STREAM_END make sense here?
return (_zlibErr != Z_OK && _zlibErr != Z_STREAM_END) || _wrapped->err();
}
void clearErr() {
// Note: we don't reset the _zlibErr here, as it is not
// clear in general how
_wrapped->clearErr();
}
void finalize() {
if (_zlibErr != Z_OK)
return;
// Process whatever remaining data there is.
processData(Z_FINISH);
// Since processData only writes out blocks of size BUFSIZE,
// we may have to flush some stragglers.
uint remainder = BUFSIZE - _stream.avail_out;
if (remainder > 0) {
if (_wrapped->write(_buf, remainder) != remainder) {
_zlibErr = Z_ERRNO;
}
}
// Finalize the wrapped savefile, too
_wrapped->finalize();
}
uint32 write(const void *dataPtr, uint32 dataSize) {
if (err())
return 0;
// Hook in the new data ...
// Note: We need to make a const_cast here, as zlib is not aware
// of the const keyword.
_stream.next_in = const_cast<byte *>((const byte *)dataPtr);
_stream.avail_in = dataSize;
// ... and flush it to disk
processData(Z_NO_FLUSH);
return dataSize - _stream.avail_in;
}
};
#endif // USE_ZLIB
Common::SeekableReadStream *wrapCompressedReadStream(Common::SeekableReadStream *toBeWrapped) {
#if defined(USE_ZLIB)
if (toBeWrapped) {
uint16 header = toBeWrapped->readUint16BE();
bool isCompressed = (header == 0x1F8B ||
((header & 0x0F00) == 0x0800 &&
header % 31 == 0));
toBeWrapped->seek(-2, SEEK_CUR);
if (isCompressed)
return new GZipReadStream(toBeWrapped);
}
#endif
return toBeWrapped;
}
Common::WriteStream *wrapCompressedWriteStream(Common::WriteStream *toBeWrapped) {
#if defined(USE_ZLIB)
if (toBeWrapped)
return new GZipWriteStream(toBeWrapped);
#endif
return toBeWrapped;
}
} // End of namespace Common

38
common/zlib.h
View file

@ -8,29 +8,31 @@
* modify it under the terms of the GNU General Public License * modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2 * as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version. * of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, * This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of * but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details. * GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License * You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software * along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* *
* $URL$ * $URL$
* $Id$ * $Id$
*
*/ */
#ifndef COMMON_ZLIB_H #ifndef COMMON_ZLIB_H
#define COMMON_ZLIB_H #define COMMON_ZLIB_H
#include "common/scummsys.h" #include "common/scummsys.h"
#include "common/stream.h"
#if defined(USE_ZLIB)
namespace Common { namespace Common {
#if defined(USE_ZLIB)
/** /**
* Thin wrapper around zlib's uncompress() function. This wrapper makes * Thin wrapper around zlib's uncompress() function. This wrapper makes
* it possible to uncompress data in engines without being forced to link * it possible to uncompress data in engines without being forced to link
@ -40,9 +42,31 @@ namespace Common {
*/ */
bool uncompress(byte *dst, unsigned long *dstLen, const byte *src, unsigned long srcLen); bool uncompress(byte *dst, unsigned long *dstLen, const byte *src, unsigned long srcLen);
} // end of namespace Common
#endif #endif
#endif /**
* Take an arbitrary SeekableReadStream and wrap it in a custom stream which
* provides transparent on-the-fly decompression. Assumes the data it
* retrieves from the wrapped stream to be either uncompressed or in gzip
* format. In the former case, the original stream is returned unmodified
* (and in particular, not wrapped).
*
* It is safe to call this with a NULL parameter (in this case, NULL is
* returned).
*/
Common::SeekableReadStream *wrapCompressedReadStream(Common::SeekableReadStream *toBeWrapped);
/**
* Take an arbitrary WriteStream and wrap it in a custom stream which provides
* transparent on-the-fly compression. The compressed data is written in the
* gzip format, unless ZLIB support has been disabled, in which case the given
* stream is returned unmodified (and in particular, not wrapped).
*
* It is safe to call this with a NULL parameter (in this case, NULL is
* returned).
*/
Common::WriteStream *wrapCompressedWriteStream(Common::WriteStream *toBeWrapped);
} // End of namespace Common
#endif