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LASTEXPRESS: Implement savegame write compression

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This commit is contained in:
Littleboy 2012-07-31 00:58:37 -04:00
parent 4728505db2
commit acd4cf82e2
2 changed files with 191 additions and 13 deletions
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174
engines/lastexpress/game/savegame.cpp
View File

@ -73,6 +73,10 @@ uint32 SavegameStream::read(void *dataPtr, uint32 dataSize) {
return readCompressed(dataPtr, dataSize);
#endif
return readUncompressed(dataPtr, dataSize);
}
uint32 SavegameStream::readUncompressed(void *dataPtr, uint32 dataSize) {
if ((int32)dataSize > size() - pos()) {
dataSize = size() - pos();
_eos = true;
@ -84,18 +88,182 @@ uint32 SavegameStream::read(void *dataPtr, uint32 dataSize) {
return dataSize;
}
void SavegameStream::process() {
void SavegameStream::writeBuffer(uint8 value, bool onlyValue) {
if (_bufferOffset == -1)
_bufferOffset = 0;
if (_bufferOffset == 256) {
_bufferOffset = 0;
Common::MemoryWriteStreamDynamic::write(_buffer, 256);
}
if (onlyValue || value < 0xFB)
_buffer[_bufferOffset] = value;
else
_buffer[_bufferOffset] = 0xFE;
_offset++;
_bufferOffset++;
if (!onlyValue && value >= 0xFB)
{
if (_bufferOffset == 256) {
_bufferOffset = 0;
Common::MemoryWriteStreamDynamic::write(_buffer, 256);
}
_buffer[_bufferOffset] = value;
_bufferOffset++;
_offset++;
}
}
uint32 SavegameStream::process() {
_enableCompression = !_enableCompression;
// TODO Flush compression buffer
#if DISABLE_COMPRESSION
return 0;
#else
switch (_status) {
default:
break;
case kStatusReading:
_status = kStatusReady;
if (_bufferOffset != -1 && _bufferOffset != 256) {
seek(_bufferOffset - 256, SEEK_CUR);
_bufferOffset = -1;
}
break;
case kStatusWriting:
switch (_valueCount) {
default:
break;
case 1:
writeBuffer(_previousValue, false);
break;
case 2:
if (_previousValue) {
writeBuffer(0xFF, true);
writeBuffer(_repeatCount, true);
writeBuffer(_previousValue, true);
break;
}
if (_repeatCount == 3) {
writeBuffer(0xFB, true);
break;
}
if (_repeatCount == -1) {
writeBuffer(0xFC, true);
break;
}
writeBuffer(0xFD, true);
writeBuffer(_repeatCount, true);
break;
}
if (_bufferOffset != -1 && _bufferOffset != 0) {
Common::MemoryWriteStreamDynamic::write(_buffer, _bufferOffset);
_bufferOffset = -1;
}
break;
}
_status = kStatusReady;
_valueCount = 0;
uint32 offset = _offset;
_offset = 0;
return offset;
#endif
}
uint32 SavegameStream::writeCompressed(const void *dataPtr, uint32 dataSize) {
error("[SavegameStream::writeCompressed] Compression not implemented!");
if (_status == kStatusReading)
error("[SavegameStream::writeCompressed] Error: Compression buffer is in read mode.");
_status = kStatusWriting;
byte *data = (byte *)dataPtr;
while (dataSize) {
switch (_valueCount) {
default:
error("[SavegameStream::writeCompressed] Invalid value count (%d)", _valueCount);
case 0:
_previousValue = *data++;
_valueCount = 1;
break;
case 1:
if (*data != _previousValue) {
writeBuffer(_previousValue, false);
_previousValue = *data;
} else {
_valueCount = 2;
_repeatCount = 2;
}
++data;
break;
case 2:
if (*data != _previousValue || _repeatCount >= 255) {
if (_previousValue) {
writeBuffer(0xFF, true);
writeBuffer(_repeatCount, true);
writeBuffer(_previousValue, true);
_previousValue = *data++;
_valueCount = 1;
break;
}
if (_repeatCount == 3) {
writeBuffer(0xFB, true);
_previousValue = *data++;
_valueCount = 1;
break;
}
if (_repeatCount == -1) {
writeBuffer(0xFC, true);
_previousValue = *data++;
_valueCount = 1;
break;
}
writeBuffer(0xFD, true);
writeBuffer(_repeatCount, true);
_previousValue = *data++;
_valueCount = 1;
}
++data;
++_repeatCount;
break;
}
--dataSize;
}
return _offset;
}
uint32 SavegameStream::readCompressed(void *dataPtr, uint32 dataSize) {
if (_status == kStatusWriting)
error("[SavegameStream::writeCompressed] Error: Compression buffer is in write mode.");
error("[SavegameStream::readCompressed] Compression not implemented!");
}

30
engines/lastexpress/game/savegame.h
View File

@ -95,9 +95,9 @@ public:
_bufferOffset = -1;
_valueCount = 0;
_previousValue = 0;
_field_15F = 0;
_repeatCount = 0;
_offset = 0;
_status = 0;
_status = kStatusReady;
memset(_buffer, 0, 256);
}
@ -109,24 +109,34 @@ public:
uint32 read(void *dataPtr, uint32 dataSize);
uint32 write(const void *dataPtr, uint32 dataSize);
void process();
uint32 process();
private:
enum CompressedStreamStatus {
kStatusReady,
kStatusReading,
kStatusWriting
};
uint32 readUncompressed(void *dataPtr, uint32 dataSize);
// Compressed data
uint32 writeCompressed(const void *dataPtr, uint32 dataSize);
uint32 readCompressed(void *dataPtr, uint32 dataSize);
void writeBuffer(uint8 value, bool onlyValue);
private:
bool _eos;
// Compression handling
bool _enableCompression;
int _bufferOffset;
int _valueCount;
byte _previousValue;
byte _field_15F;
int _offset;
int _status;
bool _enableCompression;
int16 _bufferOffset;
byte _valueCount;
byte _previousValue;
int16 _repeatCount;
uint32 _offset;
CompressedStreamStatus _status;
byte _buffer[256];
};