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scummvm/engines/sci/engine/vm_hooks.h
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2020-05-25 03:21:59 +03:00

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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.
*
*/
#ifndef SCI_ENGINE_VM_HOOKS_H
#define SCI_ENGINE_VM_HOOKS_H
#include "sci/engine/vm.h"
namespace Sci {
#define ARRAYSIZE(x) ((int)(sizeof(x) / sizeof(x[0])))
#define HOOKARRAY(x) x, ARRAYSIZE(x)
/** _hooksMap keys are built from script number and PC's offset */
struct HookHashKey {
int scriptNumber;
uint32 offset;
uint64 hash();
bool operator==(const HookHashKey &other) const {
return scriptNumber == other.scriptNumber && offset == other.offset;
}
};
/** _hooksMap value entry */
struct HookEntry {
/** These are used to make sure that the PC is indeed the requested place */
const char *objName;
Common::String selector;
int exportId;
const char *opcodeName;
/** If all the previous match, patch */
const byte *patch;
uint patchSize;
};
/** Used for allGamesHooks - from it we build the specific _hooksMap */
struct GeneralHookEntry {
SciGameId gameId;
Common::Language language; // language to be patched. UNK_LANG means to patch all languages
HookHashKey key;
HookEntry entry;
};
/** Hash key equality function */
struct HookHash : public Common::UnaryFunction<HookHashKey, uint64> {
uint64 operator()(HookHashKey val) const { return val.hash(); }
};
/** VM Hook mechanism */
class VmHooks {
public:
VmHooks();
/** Called just before executing opcode, to check if there is a requried hook */
void vm_hook_before_exec(Sci::EngineState *s);
byte *data();
bool isActive(Sci::EngineState *s);
void advance(int offset);
private:
/** Hash map of all game's hooks */
Common::HashMap<HookHashKey, HookEntry, HookHash> _hooksMap;
Common::Array<byte> _hookScriptData;
/** Used to avoid double patching in row, and to support `call`ing */
reg_t _lastPc;
/** Raised after patch has ended, to avoid confusion with situation of returning from a `call` to the patch, and continue execution of original code */
bool _just_finished;
/** Location inside patch */
int _location;
};
} // End of namespace Sci
#endif // SCI_ENGINE_VM_HOOKS_H