mirror of
https://github.com/libretro/scummvm.git
synced 2024-12-16 14:50:17 +00:00
114 lines
3.6 KiB
C++
114 lines
3.6 KiB
C++
/* 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.
|
|
*
|
|
*/
|
|
|
|
#ifndef SHORTS_SEGMENT_MANAGER_H
|
|
#define SHORTS_SEGMENT_MANAGER_H
|
|
|
|
#include "common/scummsys.h"
|
|
|
|
#if defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET)
|
|
|
|
#include "backends/plugins/elf/elf32.h"
|
|
|
|
#include "common/singleton.h"
|
|
#include "common/list.h"
|
|
|
|
#define ShortsMan ShortSegmentManager::instance()
|
|
|
|
/**
|
|
* ShortSegmentManager
|
|
*
|
|
* Since MIPS is limited to 32 bits per instruction, loading data that's further away than 16 bits
|
|
* takes several instructions. Thus, small global data (which is likely to be accessed a lot from
|
|
* multiple locations) is often put into a GP-relative area (GP standing for the global pointer register)
|
|
* in MIPS processors. This class manages these segments of small global data, and is used by the
|
|
* member functions of MIPSDLObject, which query in information from this manager in order to deal with
|
|
* this segment during the loading/unloading of plugins.
|
|
*
|
|
* Since there's no true dynamic linker to change the GP register between plugins and the main engine,
|
|
* custom ld linker scripts for both the main executable and the plugins ensure the GP-area is in the
|
|
* same place for both. The ShortSegmentManager accesses this place via the symbols __plugin_hole_start
|
|
* and __plugin_hole_end, which are defined in those custom ld linker scripts.
|
|
*/
|
|
class ShortSegmentManager : public Common::Singleton<ShortSegmentManager> {
|
|
private:
|
|
char *_shortsStart;
|
|
char *_shortsEnd;
|
|
|
|
public:
|
|
char *getShortsStart() {
|
|
return _shortsStart;
|
|
}
|
|
|
|
// Returns whether or not an absolute address is in the GP-relative section.
|
|
bool inGeneralSegment(char *addr) {
|
|
return (addr >= _shortsStart && addr < _shortsEnd);
|
|
}
|
|
|
|
class Segment {
|
|
private:
|
|
friend class ShortSegmentManager;
|
|
Segment(char *start, uint32 size, char *origAddr) :
|
|
_startAddress(start),
|
|
_size(size),
|
|
_origAddress(origAddr) {
|
|
}
|
|
|
|
virtual ~Segment() {
|
|
}
|
|
|
|
char *_startAddress; // Start of shorts segment in memory
|
|
uint32 _size; // Size of shorts segment
|
|
char *_origAddress; // Original address this segment was supposed to be at
|
|
|
|
public:
|
|
char *getStart() {
|
|
return _startAddress;
|
|
}
|
|
|
|
char *getEnd() {
|
|
return (_startAddress + _size);
|
|
}
|
|
|
|
Elf32_Addr getOffset() {
|
|
return (Elf32_Addr)(_startAddress - _origAddress);
|
|
}
|
|
|
|
bool inSegment(char *addr) {
|
|
return (addr >= _startAddress && addr <= _startAddress + _size);
|
|
}
|
|
};
|
|
|
|
Segment *newSegment(uint32 size, char *origAddr);
|
|
void deleteSegment(Segment *);
|
|
|
|
private:
|
|
ShortSegmentManager();
|
|
friend class Common::Singleton<ShortSegmentManager>;
|
|
Common::List<Segment *> _list;
|
|
char *_highestAddress;
|
|
};
|
|
|
|
#endif // defined(DYNAMIC_MODULES) && defined(USE_ELF_LOADER) && defined(MIPS_TARGET)
|
|
|
|
#endif /* SHORTS_SEGMENT_MANAGER_H */
|