diff options
Diffstat (limited to 'backends/plugins/elf/shorts-segment-manager.h')
-rw-r--r-- | backends/plugins/elf/shorts-segment-manager.h | 118 |
1 files changed, 117 insertions, 1 deletions
diff --git a/backends/plugins/elf/shorts-segment-manager.h b/backends/plugins/elf/shorts-segment-manager.h index 5692c8a07b..219648d91d 100644 --- a/backends/plugins/elf/shorts-segment-manager.h +++ b/backends/plugins/elf/shorts-segment-manager.h @@ -1 +1,117 @@ -dummy +/* 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 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 */ + |