/**

  * vim: set ts=4 :

  * =============================================================================

  * SourceMod

  * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.

  * =============================================================================

  *

  * This program is free software; you can redistribute it and/or modify it under

  * the terms of the GNU General Public License, version 3.0, as published by the

  * Free Software Foundation.

  * 

  * 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, see <http://www.gnu.org/licenses/>.

  *

  * As a special exception, AlliedModders LLC gives you permission to link the

  * code of this program (as well as its derivative works) to "Half-Life 2," the

  * "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software

  * by the Valve Corporation.  You must obey the GNU General Public License in

  * all respects for all other code used.  Additionally, AlliedModders LLC grants

  * this exception to all derivative works.  AlliedModders LLC defines further

  * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),

  * or <http://www.sourcemod.net/license.php>.

  *

  * Version: $Id$

  */

 #include "HalfLife2.h"

 #include "sourcemod.h"

 #include "sourcemm_api.h"

 #include "UserMessages.h"

 #include "PlayerManager.h"

 #include "sm_stringutil.h"

 #include <IGameConfigs.h>

 #include <compat_wrappers.h>

 #include <Logger.h>

 #include "LibrarySys.h"

 #include "logic_bridge.h"

 #include <tier0/mem.h>

 typedef ICommandLine *(*FakeGetCommandLine)();

 #if defined _WIN32

 #define TIER0_NAME			"tier0.dll"

 #define VSTDLIB_NAME		"vstdlib.dll"

 #elif defined __APPLE__

 #define TIER0_NAME			"libtier0.dylib"

 #define VSTDLIB_NAME		"libvstdlib.dylib"

 #elif defined __linux__

 #if SOURCE_ENGINE == SE_ORANGEBOXVALVE

 #define TIER0_NAME			"libtier0_srv.so"

 #define VSTDLIB_NAME		"libvstdlib_srv.so"

 #elif SOURCE_ENGINE >= SE_CSS

 #define TIER0_NAME			"libtier0.so"

 #define VSTDLIB_NAME		"libvstdlib.so"

 #else

 #define TIER0_NAME			"tier0_i486.so"

 #define VSTDLIB_NAME		"vstdlib_i486.so"

 #endif

 #endif

 CHalfLife2 g_HL2;

 ConVar *sv_lan = NULL;

 static void *g_EntList = NULL;

 static int entInfoOffset = -1;

 namespace SourceHook

 {

 	template<>

 	int HashFunction<datamap_t *>(datamap_t * const &k)

 	{

 		return reinterpret_cast<int>(k);

 	}

 	template<>

 	int Compare<datamap_t *>(datamap_t * const &k1, datamap_t * const &k2)

 	{

 		return (k1-k2);

 	}

 }

 CHalfLife2::CHalfLife2()

 {

 	m_pClasses = sm_trie_create();

 }

 CHalfLife2::~CHalfLife2()

 {

 	sm_trie_destroy(m_pClasses);

 	List<DataTableInfo *>::iterator iter;

 	DataTableInfo *pInfo;

 	for (iter=m_Tables.begin(); iter!=m_Tables.end(); iter++)

 	{

 		pInfo = (*iter);

 		delete pInfo;

 	}

 	m_Tables.clear();

 	THash<datamap_t *, DataMapTrie>::iterator h_iter;

 	for (h_iter=m_Maps.begin(); h_iter!=m_Maps.end(); h_iter++)

 	{

 		if (h_iter->val.trie)

 		{

 			sm_trie_destroy(h_iter->val.trie);

 			h_iter->val.trie = NULL;

 		}

 	}

 	m_Maps.clear();

 }

 #if SOURCE_ENGINE != SE_DARKMESSIAH

 CSharedEdictChangeInfo *g_pSharedChangeInfo = NULL;

 #endif

 #if !defined METAMOD_PLAPI_VERSION || PLAPI_VERSION < 11

 bool is_original_engine = false;

 #endif

 void CHalfLife2::OnSourceModStartup(bool late)

 {

 #if SOURCE_ENGINE != SE_DARKMESSIAH

 	/* The Ship currently is the only known game to use an older version of the engine */

 #if defined METAMOD_PLAPI_VERSION || PLAPI_VERSION >= 11

 	if (g_SMAPI->GetSourceEngineBuild() == SOURCE_ENGINE_ORIGINAL)

 #else

 	if (strcasecmp(g_SourceMod.GetGameFolderName(), "ship") == 0)

 #endif

 	{

 		is_original_engine = true;

 	}

 	else if (g_pSharedChangeInfo == NULL)

 	{

 		g_pSharedChangeInfo = engine->GetSharedEdictChangeInfo();

 	}

 #endif

 }

 void CHalfLife2::OnSourceModAllInitialized()

 {

 	m_MsgTextMsg = g_UserMsgs.GetMessageIndex("TextMsg");

 	m_HinTextMsg = g_UserMsgs.GetMessageIndex("HintText");

 	m_SayTextMsg = g_UserMsgs.GetMessageIndex("SayText");

 	m_VGUIMenu = g_UserMsgs.GetMessageIndex("VGUIMenu");

 	g_ShareSys.AddInterface(NULL, this);

 }

 void CHalfLife2::OnSourceModAllInitialized_Post()

 {

 	InitLogicalEntData();

 	InitCommandLine();

 }

 void CHalfLife2::InitLogicalEntData()

 {

 	char *addr = NULL;

 	/*

 	 * gEntList and/or g_pEntityList

 	 *

 	 * First try to lookup pointer directly for platforms with symbols.

 	 * If symbols aren't present (Windows or stripped Linux/Mac), 

 	 * attempt find via LevelShutdown + offset

 	 */

 	if (g_pGameConf->GetMemSig("gEntList", (void **)&addr))

 	{

 #if !defined PLATFORM_WINDOWS

 		if (!addr)

 		{

 			// Key exists so notify if lookup fails, but try other method.

 			g_Logger.LogError("Failed lookup of gEntList directly - Reverting to lookup via LevelShutdown");

 		}

 		else

 		{

 #endif

 			g_EntList = reinterpret_cast<void *>(addr);

 #if !defined PLATFORM_WINDOWS

 		}

 #endif

 	}

 	if (!g_EntList)

 	{

 		if (!g_pGameConf->GetMemSig("LevelShutdown", (void **)&addr))

 		{

 			g_Logger.LogError("Logical Entities not supported by this mod (LevelShutdown) - Reverting to networkable entities only");

 			return;

 		}

 		if (!addr)

 		{

 			g_Logger.LogError("Failed lookup of LevelShutdown - Reverting to networkable entities only");

 			return;

 		}

 		int offset;

 		if (!g_pGameConf->GetOffset("gEntList", &offset))

 		{

 			g_Logger.LogError("Logical Entities not supported by this mod (gEntList) - Reverting to networkable entities only");

 			return;

 		}

 		g_EntList = *reinterpret_cast<void **>(addr + offset);

 	}

 	if (!g_EntList)

 	{

 		g_Logger.LogError("Failed lookup of gEntList - Reverting to networkable entities only");

 		return;

 	}

 	if (!g_pGameConf->GetOffset("EntInfo", &entInfoOffset))

 	{

 		g_Logger.LogError("Logical Entities not supported by this mod (EntInfo) - Reverting to networkable entities only");

 		return;

 	}

 }

 void CHalfLife2::InitCommandLine()

 {

 	char path[PLATFORM_MAX_PATH];

 	char error[256];

 	g_SourceMod.BuildPath(Path_Game, path, sizeof(path), "../bin/" TIER0_NAME);

 	if (!g_LibSys.IsPathFile(path))

 	{

 		g_Logger.LogError("Could not find path for: " TIER0_NAME);

 		return;

 	}

 	ILibrary *lib = g_LibSys.OpenLibrary(path, error, sizeof(error));

 	m_pGetCommandLine = lib->GetSymbolAddress("CommandLine_Tier0");

 	/* '_Tier0' dropped on Alien Swarm version */

 	if (m_pGetCommandLine == NULL)

 	{

 		m_pGetCommandLine = lib->GetSymbolAddress("CommandLine");

 	}

 	if (m_pGetCommandLine == NULL)

 	{

 		/* We probably have a Ship engine. */

 		lib->CloseLibrary();

 		g_SourceMod.BuildPath(Path_Game, path, sizeof(path), "../bin/" VSTDLIB_NAME);

 		if (!g_LibSys.IsPathFile(path))

 		{

 			g_Logger.LogError("Could not find path for: " VSTDLIB_NAME);

 			return;

 		}

 		if ((lib = g_LibSys.OpenLibrary(path, error, sizeof(error))) == NULL)

 		{

 			g_Logger.LogError("Could not load %s: %s", path, error);

 			return;

 		}

 		m_pGetCommandLine = lib->GetSymbolAddress("CommandLine");

 		if (m_pGetCommandLine == NULL)

 		{

 			g_Logger.LogError("Could not locate any command line functionality");

 		}

 		lib->CloseLibrary();

 	}

 }

 ICommandLine *CHalfLife2::GetValveCommandLine()

 {

 	if (!m_pGetCommandLine)

 		return NULL;

 	return ((FakeGetCommandLine)((FakeGetCommandLine *)m_pGetCommandLine))();

 }

 #if !defined METAMOD_PLAPI_VERSION || PLAPI_VERSION < 11

 bool CHalfLife2::IsOriginalEngine()

 {

 	return is_original_engine;

 }

 #endif

 #if SOURCE_ENGINE != SE_DARKMESSIAH

 IChangeInfoAccessor *CBaseEdict::GetChangeAccessor()

 {

 	return engine->GetChangeAccessor( (const edict_t *)this );

 }

 #endif

 bool UTIL_FindInSendTable(SendTable *pTable, 

 						  const char *name,

 						  sm_sendprop_info_t *info,

 						  unsigned int offset)

 {

 	const char *pname;

 	int props = pTable->GetNumProps();

 	SendProp *prop;

 	for (int i=0; i<props; i++)

 	{

 		prop = pTable->GetProp(i);

 		pname = prop->GetName();

 		if (pname && strcmp(name, pname) == 0)

 		{

 			info->prop = prop;

 			info->actual_offset = offset + info->prop->GetOffset();

 			return true;

 		}

 		if (prop->GetDataTable())

 		{

 			if (UTIL_FindInSendTable(prop->GetDataTable(), 

 				name,

 				info,

 				offset + prop->GetOffset())

 				)

 			{

 				return true;

 			}

 		}

 	}

 	return false;

 }

 typedescription_t *UTIL_FindInDataMap(datamap_t *pMap, const char *name)

 {

 	while (pMap)

 	{

 		for (int i=0; i<pMap->dataNumFields; i++)

 		{

 			if (pMap->dataDesc[i].fieldName == NULL)

 			{

 				continue;

 			}

 			if (strcmp(name, pMap->dataDesc[i].fieldName) == 0)

 			{

 				return &(pMap->dataDesc[i]);

 			}

 			if (pMap->dataDesc[i].td)

 			{

 				typedescription_t *_td;

 				if ((_td=UTIL_FindInDataMap(pMap->dataDesc[i].td, name)) != NULL)

 				{

 					return _td;

 				}

 			}

 		}

 		pMap = pMap->baseMap;

 	}

 	return NULL; 

 }

 ServerClass *CHalfLife2::FindServerClass(const char *classname)

 {

 	DataTableInfo *pInfo = _FindServerClass(classname);

 	if (!pInfo)

 	{

 		return NULL;

 	}

 	return pInfo->sc;

 }

 DataTableInfo *CHalfLife2::_FindServerClass(const char *classname)

 {

 	DataTableInfo *pInfo = NULL;

 	if (!sm_trie_retrieve(m_pClasses, classname, (void **)&pInfo))

 	{

 		ServerClass *sc = gamedll->GetAllServerClasses();

 		while (sc)

 		{

 			if (strcmp(classname, sc->GetName()) == 0)

 			{

 				pInfo = new DataTableInfo;

 				pInfo->sc = sc;

 				sm_trie_insert(m_pClasses, classname, pInfo);

 				m_Tables.push_back(pInfo);

 				break;

 			}

 			sc = sc->m_pNext;

 		}

 		if (!pInfo)

 		{

 			return NULL;

 		}

 	}

 	return pInfo;

 }

 bool CHalfLife2::FindSendPropInfo(const char *classname, const char *offset, sm_sendprop_info_t *info)

 {

 	DataTableInfo *pInfo;

 	sm_sendprop_info_t *prop;

 	if ((pInfo = _FindServerClass(classname)) == NULL)

 	{

 		return false;

 	}

 	if ((prop = pInfo->lookup.retrieve(offset)) == NULL)

 	{

 		sm_sendprop_info_t temp_info;

 		if (!UTIL_FindInSendTable(pInfo->sc->m_pTable, offset, &temp_info, 0))

 		{

 			return false;

 		}

 		pInfo->lookup.insert(offset, temp_info);

 		*info = temp_info;

 	}

 	else

 	{

 		*info = *prop;

 	}

 	return true;

 }

 SendProp *CHalfLife2::FindInSendTable(const char *classname, const char *offset)

 {

 	sm_sendprop_info_t info;

 	if (!FindSendPropInfo(classname, offset, &info))

 	{

 		return NULL;

 	}

 	return info.prop;

 }

 typedescription_t *CHalfLife2::FindInDataMap(datamap_t *pMap, const char *offset)

 {

 	typedescription_t *td = NULL;

 	DataMapTrie &val = m_Maps[pMap];

 	if (!val.trie)

 	{

 		val.trie = sm_trie_create();

 	}

 	if (!sm_trie_retrieve(val.trie, offset, (void **)&td))

 	{

 		if ((td = UTIL_FindInDataMap(pMap, offset)) != NULL)

 		{

 			sm_trie_insert(val.trie, offset, td);

 		}

 	}

 	return td;

 }

 void CHalfLife2::SetEdictStateChanged(edict_t *pEdict, unsigned short offset)

 {

 #if SOURCE_ENGINE != SE_DARKMESSIAH

 	if (g_pSharedChangeInfo != NULL)

 	{

 		if (offset)

 		{

 			pEdict->StateChanged(offset);

 		}

 		else

 		{

 			pEdict->StateChanged();

 		}

 	}

 	else

 #endif

 	{

 		pEdict->m_fStateFlags |= FL_EDICT_CHANGED;

 	}

 }

 bool CHalfLife2::TextMsg(int client, int dest, const char *msg)

 {

 	bf_write *pBitBuf = NULL;

 	cell_t players[] = {client};

 	if (dest == HUD_PRINTTALK)

 	{

 		const char *chat_saytext = g_pGameConf->GetKeyValue("ChatSayText");

 		/* Use SayText user message instead */

 		if (chat_saytext != NULL && strcmp(chat_saytext, "yes") == 0)

 		{

 			char buffer[192];

 			UTIL_Format(buffer, sizeof(buffer), "%s\1\n", msg);

 			if ((pBitBuf = g_UserMsgs.StartMessage(m_SayTextMsg, players, 1, USERMSG_RELIABLE)) == NULL)

 			{

 				return false;

 			}

 			pBitBuf->WriteByte(0);

 			pBitBuf->WriteString(buffer);

 			pBitBuf->WriteByte(1);

 			g_UserMsgs.EndMessage();

 			return true;

 		}

 	}

 	if ((pBitBuf = g_UserMsgs.StartMessage(m_MsgTextMsg, players, 1, USERMSG_RELIABLE)) == NULL)

 	{

 		return false;

 	}

 	pBitBuf->WriteByte(dest);

 	pBitBuf->WriteString(msg);

 	g_UserMsgs.EndMessage();

 	return true;

 }

 bool CHalfLife2::HintTextMsg(int client, const char *msg)

 {

 	bf_write *pBitBuf = NULL;

 	cell_t players[] = {client};

 	if ((pBitBuf = g_UserMsgs.StartMessage(m_HinTextMsg, players, 1, USERMSG_RELIABLE)) == NULL)

 	{

 		return false;

 	}

 	const char *pre_byte = g_pGameConf->GetKeyValue("HintTextPreByte");

 	if (pre_byte != NULL && strcmp(pre_byte, "yes") == 0)

 	{

 		pBitBuf->WriteByte(1);

 	}

 	pBitBuf->WriteString(msg);

 	g_UserMsgs.EndMessage();

 	return true;

 }

 bool CHalfLife2::HintTextMsg(cell_t *players, int count, const char *msg)

 {

 	bf_write *pBitBuf = NULL;

 	if ((pBitBuf = g_UserMsgs.StartMessage(m_HinTextMsg, players, count, USERMSG_RELIABLE)) == NULL)

 	{

 		return false;

 	}

 	const char *pre_byte = g_pGameConf->GetKeyValue("HintTextPreByte");

 	if (pre_byte != NULL && strcmp(pre_byte, "yes") == 0)

 	{

 		pBitBuf->WriteByte(1);

 	}

 	pBitBuf->WriteString(msg);

 	g_UserMsgs.EndMessage();

 	return true;

 }

 bool CHalfLife2::ShowVGUIMenu(int client, const char *name, KeyValues *data, bool show)

 {

 	bf_write *pBitBuf = NULL;

 	KeyValues *SubKey = NULL;

 	int count = 0;

 	cell_t players[] = {client};

 	if ((pBitBuf = g_UserMsgs.StartMessage(m_VGUIMenu, players, 1, USERMSG_RELIABLE)) == NULL)

 	{

 		return false;

 	}

 	if (data)

 	{

 		SubKey = data->GetFirstSubKey();

 		while (SubKey)

 		{

 			count++;

 			SubKey = SubKey->GetNextKey();

 		}

 		SubKey = data->GetFirstSubKey();

 	}

 	pBitBuf->WriteString(name);

 	pBitBuf->WriteByte((show) ? 1 : 0);

 	pBitBuf->WriteByte(count);

 	while (SubKey)

 	{

 		pBitBuf->WriteString(SubKey->GetName());

 		pBitBuf->WriteString(SubKey->GetString());

 		SubKey = SubKey->GetNextKey();

 	}

 	g_UserMsgs.EndMessage();

 	return true;

 }

 void CHalfLife2::AddToFakeCliCmdQueue(int client, int userid, const char *cmd)

 {

 	DelayedFakeCliCmd *pFake;

 	if (m_FreeCmds.empty())

 	{

 		pFake = new DelayedFakeCliCmd;

 	} else {

 		pFake = m_FreeCmds.front();

 		m_FreeCmds.pop();

 	}

 	pFake->client = client;

 	pFake->userid = userid;

 	pFake->cmd.assign(cmd);

 	m_CmdQueue.push(pFake);

 }

 void CHalfLife2::ProcessFakeCliCmdQueue()

 {

 	while (!m_CmdQueue.empty())

 	{

 		DelayedFakeCliCmd *pFake = m_CmdQueue.first();

 		if (g_Players.GetClientOfUserId(pFake->userid) == pFake->client)

 		{

 			CPlayer *pPlayer = g_Players.GetPlayerByIndex(pFake->client);

 			serverpluginhelpers->ClientCommand(pPlayer->GetEdict(), pFake->cmd.c_str());

 		}

 		m_CmdQueue.pop();

 	}

 }

 bool CHalfLife2::IsLANServer()

 {

 	sv_lan = icvar->FindVar("sv_lan");

 	if (!sv_lan)

 	{

 		return false;

 	}

 	return (sv_lan->GetInt() != 0);

 }

 bool CHalfLife2::KVLoadFromFile(KeyValues *kv, IBaseFileSystem *filesystem, const char *resourceName, const char *pathID)

 {

 #if defined METAMOD_PLAPI_VERSION || PLAPI_VERSION >= 11

 	if (g_SMAPI->GetSourceEngineBuild() == SOURCE_ENGINE_ORIGINAL)

 #else

 	if (strcasecmp(g_SourceMod.GetGameFolderName(), "ship") == 0)

 #endif

 	{

 		Assert(filesystem);

 #ifdef _MSC_VER

 		Assert(_heapchk() == _HEAPOK);

 #endif

 		FileHandle_t f = filesystem->Open(resourceName, "rb", pathID);

 		if (!f)

 			return false;

 		// load file into a null-terminated buffer

 		int fileSize = filesystem->Size(f);

 		char *buffer = (char *)MemAllocScratch(fileSize + 1);

 		Assert(buffer);

 		filesystem->Read(buffer, fileSize, f); // read into local buffer

 		buffer[fileSize] = 0; // null terminate file as EOF

 		filesystem->Close( f );	// close file after reading

 		bool retOK = kv->LoadFromBuffer( resourceName, buffer, filesystem );

 		MemFreeScratch();

 		return retOK;

 	}

 	else

 	{

 		return kv->LoadFromFile(filesystem, resourceName, pathID);

 	}

 }

 void CHalfLife2::PushCommandStack(const CCommand *cmd)

 {

 	CachedCommandInfo info;

 	info.args = cmd;

 #if SOURCE_ENGINE <= SE_DARKMESSIAH

 	strncopy(info.cmd, cmd->Arg(0), sizeof(info.cmd));

 #endif

 	m_CommandStack.push(info);

 }

 const CCommand *CHalfLife2::PeekCommandStack()

 {

 	if (m_CommandStack.empty())

 	{

 		return NULL;

 	}

 	return m_CommandStack.front().args;

 }

 void CHalfLife2::PopCommandStack()

 {

 	m_CommandStack.pop();

 }

 const char *CHalfLife2::CurrentCommandName()

 {

 #if SOURCE_ENGINE >= SE_ORANGEBOX

 	return m_CommandStack.front().args->Arg(0);

 #else

 	return m_CommandStack.front().cmd;

 #endif

 }

 void CHalfLife2::AddDelayedKick(int client, int userid, const char *msg)

 {

 	DelayedKickInfo kick;

 	kick.client = client;

 	kick.userid = userid;

 	UTIL_Format(kick.buffer, sizeof(kick.buffer), "%s", msg);

 	m_DelayedKicks.push(kick);

 }

 void CHalfLife2::ProcessDelayedKicks()

 {

 	while (!m_DelayedKicks.empty())

 	{

 		DelayedKickInfo info = m_DelayedKicks.first();

 		m_DelayedKicks.pop();

 		CPlayer *player = g_Players.GetPlayerByIndex(info.client);

 		if (player == NULL || player->GetUserId() != info.userid)

 		{

 			continue;

 		}

 		player->Kick(info.buffer);

 	}

 }

 edict_t *CHalfLife2::EdictOfIndex(int index)

 {

 	return ::PEntityOfEntIndex(index);

 }

 int CHalfLife2::IndexOfEdict(edict_t *pEnt)

 {

 	return ::IndexOfEdict(pEnt);

 }

 edict_t *CHalfLife2::GetHandleEntity(CBaseHandle &hndl)

 {

 	if (!hndl.IsValid())

 	{

 		return NULL;

 	}

 	int index = hndl.GetEntryIndex();

 	edict_t *pStoredEdict;

 	CBaseEntity *pStoredEntity;

 	if (!IndexToAThings(index, &pStoredEntity, &pStoredEdict))

 	{

 		return NULL;

 	}

 	if (pStoredEdict == NULL || pStoredEntity == NULL)

 	{

 		return NULL;

 	}

 	IServerEntity *pSE = pStoredEdict->GetIServerEntity();

 	if (pSE == NULL)

 	{

 		return NULL;

 	}

 	if (pSE->GetRefEHandle() != hndl)

 	{

 		return NULL;

 	}

 	return pStoredEdict;

 }

 void CHalfLife2::SetHandleEntity(CBaseHandle &hndl, edict_t *pEnt)

 {

 	IServerEntity *pEntOther = pEnt->GetIServerEntity();

 	if (pEntOther == NULL)

 	{

 		return;

 	}

 	hndl.Set(pEntOther);

 }

 const char *CHalfLife2::GetCurrentMap()

 {

 	return STRING(gpGlobals->mapname);

 }

 void CHalfLife2::ServerCommand(const char *buffer)

 {

 	engine->ServerCommand(buffer);

 }

 cell_t CHalfLife2::EntityToReference(CBaseEntity *pEntity)

 {

 	IServerUnknown *pUnknown = (IServerUnknown *)pEntity;

 	CBaseHandle hndl = pUnknown->GetRefEHandle();

 	return (hndl.ToInt() | (1<<31));

 }

 CBaseEntity *CHalfLife2::ReferenceToEntity(cell_t entRef)

 {

 	if ((unsigned)entRef == INVALID_EHANDLE_INDEX)

 	{

 		return NULL;

 	}

 	CEntInfo *pInfo = NULL;

 	if (entRef & (1<<31))

 	{

 		/* Proper ent reference */

 		int hndlValue = entRef & ~(1<<31);

 		CBaseHandle hndl(hndlValue);

 		pInfo = LookupEntity(hndl.GetEntryIndex());

 		if (!pInfo || pInfo->m_SerialNumber != hndl.GetSerialNumber())

 		{

 			return NULL;

 		}

 	}

 	else

 	{

 		/* Old style index only */

 		pInfo = LookupEntity(entRef);

 	}

 	if (!pInfo)

 	{

 		return NULL;

 	}

 	IServerUnknown *pUnk = static_cast<IServerUnknown *>(pInfo->m_pEntity);

 	if (pUnk)

 	{

 		return pUnk->GetBaseEntity();

 	}

 	return NULL;

 }

 /**

  * Retrieves the CEntInfo pointer from g_EntList for a given entity index

  */

 CEntInfo *CHalfLife2::LookupEntity(int entIndex)

 {

 	// Make sure that our index is within the bounds of the global ent array

 	if (entIndex < 0 || entIndex >= NUM_ENT_ENTRIES)

 	{

 		return NULL;

 	}

 	if (!g_EntList || entInfoOffset == -1)

 	{

 		/* Attempt to use engine interface instead */

 		static CEntInfo tempInfo;

 		tempInfo.m_pNext = NULL;

 		tempInfo.m_pPrev = NULL;

 		edict_t *pEdict = PEntityOfEntIndex(entIndex);

 		if (!pEdict)

 		{

 			return NULL;

 		}

 		IServerUnknown *pUnk = pEdict->GetUnknown();

 		if (!pUnk)

 		{

 			return NULL;

 		}

 		tempInfo.m_pEntity = pUnk;

 		tempInfo.m_SerialNumber = pUnk->GetRefEHandle().GetSerialNumber();

 		return &tempInfo;

 	}

 	CEntInfo *pArray = (CEntInfo *)(((unsigned char *)g_EntList) + entInfoOffset);

 	return &pArray[entIndex];

 }

 /**

 	SERIAL_MASK = 0x7fff (15 bits)

 	#define	MAX_EDICT_BITS				11

 	#define NUM_ENT_ENTRY_BITS		(MAX_EDICT_BITS + 1)

 	m_Index = iEntry | (iSerialNumber << NUM_ENT_ENTRY_BITS); 

 	Top 5 bits of a handle are unused.

 	Bit 31 - Our 'reference' flag indicator

 */

 cell_t CHalfLife2::IndexToReference(int entIndex)

 {

 	CBaseEntity *pEnt = ReferenceToEntity(entIndex);

 	if (!pEnt)

 	{

 		return INVALID_EHANDLE_INDEX;

 	}

 	return EntityToReference(pEnt);

 }

 int CHalfLife2::ReferenceToIndex(cell_t entRef)

 {

 	if ((unsigned)entRef == INVALID_EHANDLE_INDEX)

 	{

 		return INVALID_EHANDLE_INDEX;

 	}

 	if (entRef & (1<<31))

 	{

 		/* Proper ent reference */

 		int hndlValue = entRef & ~(1<<31);

 		CBaseHandle hndl(hndlValue);

 		CEntInfo *pInfo = LookupEntity(hndl.GetEntryIndex());

 		if (pInfo->m_SerialNumber != hndl.GetSerialNumber())

 		{

 			return INVALID_EHANDLE_INDEX;

 		}

 		return hndl.GetEntryIndex();

 	}

 	return entRef;

 }

 cell_t CHalfLife2::EntityToBCompatRef(CBaseEntity *pEntity)

 {

 	if (pEntity == NULL)

 	{

 		return INVALID_EHANDLE_INDEX;

 	}

 	IServerUnknown *pUnknown = (IServerUnknown *)pEntity;

 	CBaseHandle hndl = pUnknown->GetRefEHandle();

 	if (hndl == INVALID_EHANDLE_INDEX)

 	{

 		return INVALID_EHANDLE_INDEX;

 	}

 	if (hndl.GetEntryIndex() >= MAX_EDICTS)

 	{

 		return (hndl.ToInt() | (1<<31));

 	}

 	else

 	{

 		return hndl.GetEntryIndex();

 	}

 }

 cell_t CHalfLife2::ReferenceToBCompatRef(cell_t entRef)

 {

 	if ((unsigned)entRef == INVALID_EHANDLE_INDEX)

 	{

 		return INVALID_EHANDLE_INDEX;

 	}

 	int hndlValue = entRef & ~(1<<31);

 	CBaseHandle hndl(hndlValue);

 	if (hndl.GetEntryIndex() < MAX_EDICTS)

 	{

 		return hndl.GetEntryIndex();

 	}

 	return entRef;

 }

 void *CHalfLife2::GetGlobalEntityList()

 {

 	return g_EntList;

 }