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+/* 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.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#if defined(DYNAMIC_MODULES) && defined(MIPS_TARGET)
+
+#ifndef SHORTS_SEGMENT_MANAGER_H
+#define SHORTS_SEGMENT_MANAGER_H
+
+#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 ((char *)addr >= _shortsStart && (char *)addr < _shortsEnd);
+ }
+
+ class Segment {
+ private:
+ friend class ShortSegmentManager;
+ Segment(char *start, int size, char *origAddr) : _startAddress(start), _size(size), _origAddress(origAddr) {}
+ ~Segment() {}
+ char *_startAddress; // Start of shorts segment in memory
+ int _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 ((char *)addr >= _startAddress && (char *)addr <= _startAddress + _size);
+ }
+ };
+
+ Segment *newSegment(int size, char *origAddr);
+ void deleteSegment(Segment *);
+
+private:
+ ShortSegmentManager();
+ friend class Common::Singleton<ShortSegmentManager>;
+ Common::List<Segment *> _list;
+ char *_highestAddress;
+};
+
+#endif /* SHORTS_SEGMENT_MANAGER_H */
+
+#endif /* defined(DYNAMIC_MODULES) && defined(MIPS_TARGET) */