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common/serializer.h
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common/serializer.h
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/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#ifndef COMMON_SERIALIZER_H
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#define COMMON_SERIALIZER_H
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#include "common/stream.h"
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#include "common/str.h"
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namespace Common {
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/**
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* @defgroup common_serializer Serializer
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* @ingroup common
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*
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* @brief API for serializing data.
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*
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* @{
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*/
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#define VER(x) Common::Serializer::Version(x)
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#define SYNC_AS(SUFFIX,TYPE,SIZE) \
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template<typename T> \
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void syncAs ## SUFFIX(T &val, Version minVersion = 0, Version maxVersion = kLastVersion) { \
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if (_version < minVersion || _version > maxVersion) \
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return; \
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if (_loadStream) \
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val = static_cast<T>(_loadStream->read ## SUFFIX()); \
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else { \
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TYPE tmp = val; \
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_saveStream->write ## SUFFIX(tmp); \
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} \
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_bytesSynced += SIZE; \
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}
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#define SYNC_PRIMITIVE(suffix) \
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template <typename T> \
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static inline void suffix(Serializer &s, T &value) { \
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s.syncAs##suffix(value); \
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}
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/**
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* This class allows syncing / serializing data (primarily game savestates)
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* between memory and Read/WriteStreams.
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* It optionally supports versioning the serialized data (client code must
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* use the syncVersion() method for this). This makes it possible to support
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* multiple versions of a savegame format with a single codepath
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*
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* This class was heavily inspired by the save/load code in the SCUMM engine.
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*
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* @todo Maybe rename this to Synchronizer?
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*
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* @todo One feature the SCUMM code has but that is missing here: Support for
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* syncing arrays of a given type and *fixed* size; and also support
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* for when the array size changed between versions. Also, support for
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* 2D-arrays.
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*
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* @todo Proper error handling!
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*/
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class Serializer {
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public:
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typedef uint32 Version;
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static const Version kLastVersion = 0xFFFFFFFF;
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SYNC_PRIMITIVE(Uint32LE)
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SYNC_PRIMITIVE(Uint32BE)
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SYNC_PRIMITIVE(Sint32LE)
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SYNC_PRIMITIVE(Sint32BE)
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SYNC_PRIMITIVE(FloatLE)
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SYNC_PRIMITIVE(FloatBE)
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SYNC_PRIMITIVE(DoubleLE)
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SYNC_PRIMITIVE(DoubleBE)
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SYNC_PRIMITIVE(Uint16LE)
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SYNC_PRIMITIVE(Uint16BE)
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SYNC_PRIMITIVE(Sint16LE)
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SYNC_PRIMITIVE(Sint16BE)
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SYNC_PRIMITIVE(Byte)
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SYNC_PRIMITIVE(SByte)
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protected:
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SeekableReadStream *_loadStream;
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WriteStream *_saveStream;
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uint _bytesSynced;
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Version _version;
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public:
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Serializer(SeekableReadStream *in, WriteStream *out)
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: _loadStream(in), _saveStream(out), _bytesSynced(0), _version(0) {
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assert(in || out);
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}
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virtual ~Serializer() {}
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inline bool isSaving() { return (_saveStream != 0); }
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inline bool isLoading() { return (_loadStream != 0); }
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SYNC_AS(Byte, byte, 1)
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SYNC_AS(SByte, int8, 1)
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SYNC_AS(Uint16LE, uint16, 2)
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SYNC_AS(Uint16BE, uint16, 2)
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SYNC_AS(Sint16LE, int16, 2)
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SYNC_AS(Sint16BE, int16, 2)
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SYNC_AS(Uint32LE, uint32, 4)
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SYNC_AS(Uint32BE, uint32, 4)
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SYNC_AS(Sint32LE, int32, 4)
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SYNC_AS(Sint32BE, int32, 4)
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SYNC_AS(FloatLE, float, 4)
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SYNC_AS(FloatBE, float, 4)
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SYNC_AS(DoubleLE, double, 8)
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SYNC_AS(DoubleBE, double, 8)
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/**
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* Returns true if an I/O failure occurred.
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* This flag is never cleared automatically. In order to clear it,
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* client code has to call clearErr() explicitly.
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*/
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bool err() const {
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if (_saveStream)
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return _saveStream->err();
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else
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return _loadStream->err();
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}
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/**
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* Reset the I/O error status as returned by err().
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*/
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void clearErr() {
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if (_saveStream)
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_saveStream->clearErr();
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else
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_loadStream->clearErr();
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}
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/**
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* Sync the "version" of the savegame we are loading/creating.
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* @param currentVersion current format version, used when writing a new file
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* @return true if the version of the savestate is not too new.
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*/
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bool syncVersion(Version currentVersion) {
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_version = currentVersion;
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syncAsUint32LE(_version);
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return _version <= currentVersion;
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}
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/**
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* Return the version of the savestate being serialized. Useful if the engine
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* needs to perform additional adjustments when loading old savestates.
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*/
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Version getVersion() const { return _version; }
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/**
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* Manually set the version
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*/
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void setVersion(Version version) { _version = version; }
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/**
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* Return the total number of bytes synced so far.
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*/
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uint bytesSynced() const { return _bytesSynced; }
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/**
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* Skip a number of bytes in the data stream.
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* This is useful to skip obsolete fields in old savestates.
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*/
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void skip(uint32 size, Version minVersion = 0, Version maxVersion = kLastVersion) {
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if (_version < minVersion || _version > maxVersion)
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return; // Ignore anything which is not supposed to be present in this save game version
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_bytesSynced += size;
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if (isLoading())
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_loadStream->skip(size);
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else {
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while (size--)
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_saveStream->writeByte(0);
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}
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}
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/**
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* Sync a block of arbitrary fixed-length data.
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*/
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void syncBytes(byte *buf, uint32 size, Version minVersion = 0, Version maxVersion = kLastVersion) {
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if (_version < minVersion || _version > maxVersion)
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return; // Ignore anything which is not supposed to be present in this save game version
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if (isLoading())
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_loadStream->read(buf, size);
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else
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_saveStream->write(buf, size);
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_bytesSynced += size;
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}
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/**
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* Sync a 'magic id' of up to 256 bytes, and return whether it matched.
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* When saving, this will simply write out the magic id and return true.
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* When loading, this will read the specified number of bytes, compare it
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* to the given magic id and return true on a match, false otherwise.
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*
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* A typical magic id is a FOURCC like 'MAGI'.
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*
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* @param magic magic id as a byte sequence
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* @param size length of the magic id in bytes
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* @return true if the magic id matched, false otherwise
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*/
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bool matchBytes(const char *magic, byte size, Version minVersion = 0, Version maxVersion = kLastVersion) {
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if (_version < minVersion || _version > maxVersion)
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return true; // Ignore anything which is not supposed to be present in this save game version
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bool match;
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if (isSaving()) {
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_saveStream->write(magic, size);
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match = true;
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} else {
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char buf[256];
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_loadStream->read(buf, size);
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match = (0 == memcmp(buf, magic, size));
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}
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_bytesSynced += size;
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return match;
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}
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/**
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* Sync a C-string, by treating it as a zero-terminated byte sequence.
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* @todo Replace this method with a special Syncer class for Common::String
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*/
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void syncString(String &str, Version minVersion = 0, Version maxVersion = kLastVersion) {
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if (_version < minVersion || _version > maxVersion)
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return; // Ignore anything which is not supposed to be present in this save game version
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if (isLoading()) {
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char c;
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str.clear();
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while ((c = _loadStream->readByte())) {
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str += c;
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_bytesSynced++;
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}
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_bytesSynced++;
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} else {
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_saveStream->writeString(str);
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_saveStream->writeByte(0);
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_bytesSynced += str.size() + 1;
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}
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}
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/**
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* Sync a U32-string
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*/
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void syncString32(U32String &str, Version minVersion = 0, Version maxVersion = kLastVersion) {
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if (_version < minVersion || _version > maxVersion)
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return; // Ignore anything which is not supposed to be present in this save game version
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uint32 len = str.size();
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syncAsUint32LE(len);
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if (isLoading()) {
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U32String::value_type *sl = new U32String::value_type[len];
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for (uint i = 0; i < len; i++)
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syncAsUint32LE(sl[i]);
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str = U32String(sl, len);
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delete[] sl;
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} else {
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for (uint i = 0; i < len; i++)
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_saveStream->writeUint32LE(str[i]);
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_bytesSynced += 4 * len;
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}
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}
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template <typename T>
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void syncArray(T *arr, size_t entries, void (*serializer)(Serializer &, T &), Version minVersion = 0, Version maxVersion = kLastVersion) {
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if (_version < minVersion || _version > maxVersion)
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return;
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for (size_t i = 0; i < entries; ++i) {
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serializer(*this, arr[i]);
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}
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}
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};
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#undef SYNC_PRIMITIVE
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#undef SYNC_AS
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// Mixin class / interface
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// TODO: Maybe rename this to Syncable ?
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class Serializable {
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public:
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virtual ~Serializable() {}
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// Maybe rename this method to "syncWithSerializer" or "syncUsingSerializer" ?
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virtual void saveLoadWithSerializer(Serializer &ser) = 0;
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};
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/** @} */
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} // End of namespace Common
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#endif
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