/**

  * vim: set ts=4 :

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

  * SourceMod BinTools Extension

  * 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: CallMaker.h 1964 2008-03-27 04:54:56Z damagedsoul $

  */

 #if defined HOOKING_ENABLED

 #include "jit_compile.h"

 #include "sm_platform.h"

 #include "extension.h"

 /********************

  * Assembly Opcodes *

  ********************/

 inline void Write_Function_Prologue(JitWriter *jit, bool RetInMemory)

 {

 	//push ebp

 	//push ebx

 	//mov ebp, esp

 	IA32_Push_Reg(jit, REG_EBP);

 	IA32_Push_Reg(jit, REG_EBX);

 	IA32_Mov_Reg_Rm(jit, REG_EBP, REG_ESP, MOD_REG);

 #if defined PLATFORM_WINDOWS

 	//mov ebx, ecx

 	IA32_Mov_Reg_Rm(jit, REG_EBX, REG_ECX, MOD_REG);

 #elif defined PLATFORM_LINUX || defined PLATFORM_APPLE

 	//mov ebx, [ebp+12+(RetInMemory)?4:0]

 	IA32_Mov_Reg_Rm_Disp8(jit, REG_EBX, REG_EBP, 12+((RetInMemory)?4:0));

 #endif

 }

 inline void Write_Function_Epilogue(JitWriter *jit, unsigned short size)

 {

 	//mov esp, ebp

 	//pop ebx

 	//pop ebp

 	//ret <value>

 	IA32_Mov_Reg_Rm(jit, REG_ESP, REG_EBP, MOD_REG);

 	IA32_Pop_Reg(jit, REG_EBX);

 	IA32_Pop_Reg(jit, REG_EBP);

 	if (size == 0)

 	{

 		IA32_Return(jit);

 	}

 	else

 	{

 		IA32_Return_Popstack(jit, size);

 	}

 }

 inline void Write_Stack_Alloc(JitWriter *jit, jit_uint32_t size)

 {

 	//sub esp, <value>

 	if (size <= SCHAR_MAX)

 	{

 		IA32_Sub_Rm_Imm8(jit, REG_ESP, (jit_int8_t)size, MOD_REG);

 	}

 	else

 	{

 		IA32_Sub_Rm_Imm32(jit, REG_ESP, size, MOD_REG);

 	}

 }

 inline void Write_Copy_Params(JitWriter *jit, bool RetInMemory, jit_uint32_t retsize, jit_uint32_t paramsize)

 {

 	//:TODO: inline this memcpy!! - For small numbers of params mov's (with clever reg allocation?) would be faster

 	//cld

 	//push edi

 	//push esi

 	//lea edi, [ebp-<retsize>-<paramsize>]

 	//lea esi, [ebp+12+(RetInMemory)?4:0]

 	//if dwords

 	// mov ecx, <dwords>

 	// rep movsd

 	//if bytes

 	// mov ecx, <bytes>

 	// rep movsb

 	//pop esi

 	//pop edi

 	jit_int32_t offs;

 	jit_uint32_t dwords = paramsize >> 2;

 	jit_uint32_t bytes = paramsize & 0x3;

 	IA32_Cld(jit);

 	IA32_Push_Reg(jit, REG_EDI);

 	IA32_Push_Reg(jit, REG_ESI);

 	offs = -(jit_int32_t)retsize - paramsize;

 	if (offs > SCHAR_MIN)

 	{

 		IA32_Lea_DispRegImm8(jit, REG_EDI, REG_EBP, (jit_int8_t)offs);

 	}

 	else

 	{

 		IA32_Lea_DispRegImm32(jit, REG_EDI, REG_EBP, offs);

 	}

 	offs = 12 + ((RetInMemory) ? sizeof(void *) : 0);

 #if defined PLATFORM_LINUX || defined PLATFORM_APPLE

 	offs += 4;

 #endif

 	if (offs < SCHAR_MAX)

 	{

 		IA32_Lea_DispRegImm8(jit, REG_ESI, REG_EBP, (jit_int8_t)offs);

 	}

 	else

 	{

 		IA32_Lea_DispRegImm32(jit, REG_ESI, REG_EBP, offs);

 	}

 	if (dwords)

 	{

 		IA32_Mov_Reg_Imm32(jit, REG_ECX, dwords);

 		IA32_Rep(jit);

 		IA32_Movsd(jit);

 	}

 	if (bytes)

 	{

 		IA32_Mov_Reg_Imm32(jit, REG_ECX, bytes);

 		IA32_Rep(jit);

 		IA32_Movsb(jit);

 	}

 	IA32_Pop_Reg(jit, REG_ESI);

 	IA32_Pop_Reg(jit, REG_EDI);

 }

 inline void Write_Push_Params(JitWriter *jit, 

 							  bool isretvoid, 

 							  bool isvoid, 

 							  jit_uint32_t retsize, 

 							  jit_uint32_t paramsize, 

 							  HookWrapper *pWrapper)

 {

 	//and esp, 0xFFFFFFF0

 	IA32_And_Rm_Imm8(jit, REG_ESP, MOD_REG, -16);

 	//if retvoid

 	// push 0

 	//else

 	// lea reg, [ebp-<retsize>]

 	// push reg

 	if (isretvoid)

 	{

 		IA32_Push_Imm8(jit, 0);

 	}

 	else

 	{

 		jit_int32_t offs = -(jit_int32_t)retsize;

 		if (offs >= SCHAR_MIN)

 		{

 			IA32_Lea_DispRegImm8(jit, REG_EAX, REG_EBP, (jit_int8_t)offs);

 		}

 		else

 		{

 			IA32_Lea_DispRegImm32(jit, REG_EAX, REG_EBP, offs);

 		}

 		IA32_Push_Reg(jit, REG_EAX);

 	}

 	//if void

 	// push 0

 	//else

 	// lea reg, [ebp-<retsize>-<paramsize>]

 	// push reg

 	if (isvoid)

 	{

 		IA32_Push_Imm8(jit, 0);

 	}

 	else

 	{

 		jit_int32_t offs = -(jit_int32_t)retsize - paramsize;

 		if (offs > SCHAR_MIN)

 		{

 			IA32_Lea_DispRegImm8(jit, REG_EDX, REG_EBP, (jit_int8_t)offs);

 		} else {

 			IA32_Lea_DispRegImm32(jit, REG_EDX, REG_EBP, offs);

 		}

 		IA32_Push_Reg(jit, REG_EDX);

 	}

 	//push eax (thisptr)

 	//IA32_Push_Reg(jit, REG_ECX);

 	//push ebx

 	IA32_Push_Reg(jit, REG_EBX);

 	//push <pWrapper>

 	IA32_Push_Imm32(jit, (jit_int32_t)pWrapper);

 }

 inline void Write_Call_Handler(JitWriter *jit, void *addr)

 {

 	//call <addr>

 	jitoffs_t call = IA32_Call_Imm32(jit, 0);

 	IA32_Write_Jump32_Abs(jit, call, addr);

 }

 inline void Write_Copy_RetVal(JitWriter *jit, SourceHook::PassInfo *pRetInfo)

 {

 	/* If the return value is a reference the size will probably be >sizeof(void *)

 	* for objects, we need to fix that so we can actually return the reference.

 	*/

 	size_t size = pRetInfo->size;

 	if (pRetInfo->flags & PASSFLAG_BYREF)

 	{

 		size = sizeof(void *);

 	}

 	if (pRetInfo->type == SourceHook::PassInfo::PassType_Float &&

 		pRetInfo->flags & SourceHook::PassInfo::PassFlag_ByVal)

 	{

 		switch (size)

 		{

 		case 4:

 			{

 				//fld DWORD PTR [ebp-4]

 				IA32_Fld_Mem32_Disp8(jit, REG_EBP, -4);

 				break;

 			}

 		case 8:

 			{

 				//fld QWORD PTR [ebp-8]

 				IA32_Fld_Mem64_Disp8(jit, REG_EBP, -8);

 				break;

 			}

 		}

 	}

 	else if (pRetInfo->type == SourceHook::PassInfo::PassType_Object &&

 		pRetInfo->flags & SourceHook::PassInfo::PassFlag_ByVal)

 	{

 		//cld

 		//push edi

 		//push esi

 		//mov edi, [ebp+12]

 		//lea esi, [ebp-<retsize>]

 		//if dwords

 		// mov ecx, <dwords>

 		// rep movsd

 		//if bytes

 		// mov ecx, <bytes>

 		// rep movsb

 		//pop esi

 		//pop edi

 		jit_int32_t offs;

 		jit_uint32_t dwords = size >> 2;

 		jit_uint32_t bytes = size & 0x3;

 		IA32_Cld(jit);

 		IA32_Push_Reg(jit, REG_EDI);

 		IA32_Push_Reg(jit, REG_ESI);

 		IA32_Mov_Reg_Rm_Disp8(jit, REG_EDI, REG_EBP, 12);

 		offs = -(jit_int32_t)pRetInfo->size;

 		if (offs >= SCHAR_MIN)

 		{

 			IA32_Lea_DispRegImm8(jit, REG_ESI, REG_EBP, (jit_int8_t)offs);

 		}

 		else

 		{

 			IA32_Lea_DispRegImm32(jit, REG_ESI, REG_EBP, offs);

 		}

 		IA32_Mov_Reg_Rm(jit, REG_EAX, REG_EDI, MOD_REG);

 		if (dwords)

 		{

 			IA32_Mov_Reg_Imm32(jit, REG_ECX, dwords);

 			IA32_Rep(jit);

 			IA32_Movsd(jit);

 		}

 		if (bytes)

 		{

 			IA32_Mov_Reg_Imm32(jit, REG_ECX, bytes);

 			IA32_Rep(jit);

 			IA32_Movsb(jit);

 		}

 		IA32_Pop_Reg(jit, REG_ESI);

 		IA32_Pop_Reg(jit, REG_EDI);

 	}

 	else

 	{

 		switch (size)

 		{

 		case 1:

 			{

 				//mov al, BYTE PTR [ebp-4]

 				IA32_Mov_Reg8_Rm8_Disp8(jit, REG_EAX, REG_EBP, -4);

 				break;

 			}

 		case 2:

 			{

 				//mov ax, WORD PTR [ebp-4]

 				jit->write_ubyte(IA32_16BIT_PREFIX);

 				IA32_Mov_Reg_Rm_Disp8(jit, REG_EAX, REG_EBP, -4);

 				break;

 			}

 		case 4:

 			{

 				//mov eax, DWORD PTR [ebp-4]

 				IA32_Mov_Reg_Rm_Disp8(jit, REG_EAX, REG_EBP, -4);

 				break;

 			}

 		case 8:

 			{

 				//mov eax, DWORD PTR [ebp-8]

 				//mov edx, DWORD PTR [ebp-4]

 				//:TODO: this is broken due to SH

 				IA32_Mov_Reg_Rm_Disp8(jit, REG_EAX, REG_EBP, -8);

 				IA32_Mov_Reg_Rm_Disp8(jit, REG_EDX, REG_EBP, -4);

 				break;

 			}

 		}

 	}

 }

 /******************************

  * Assembly Compiler Function *

  ******************************/

 void *JIT_HookCompile(HookWrapper *pWrapper)

 {

 	JitWriter writer;

 	JitWriter *jit = &writer;

 	jit_uint32_t CodeSize = 0;

 	jit_uint32_t ParamSize = pWrapper->GetParamSize();

 	jit_uint32_t RetSize = pWrapper->GetRetSize();

 	/* Local variable size allocated in the stack for the param and retval buffers */

 	jit_uint32_t LocalVarSize = ParamSize + RetSize;

 	/* Check if the return value is returned in memory */

 	bool RetInMemory = false;

 	SourceHook::PassInfo *pRetInfo = &pWrapper->GetProtoInfo()->retPassInfo;

 	if ((pRetInfo->type == SourceHook::PassInfo::PassType_Object) && 

 		(pRetInfo->flags & SourceHook::PassInfo::PassFlag_ByVal))

 	{

 		RetInMemory = true;

 	}

 	writer.outbase = NULL;

 	writer.outptr = NULL;

 jit_rewind:

 	/* Write the function prologue */

 	Write_Function_Prologue(jit, RetInMemory);

 	/* Allocate the local variables into the stack */

 	if (LocalVarSize)

 	{

 		Write_Stack_Alloc(jit, LocalVarSize);

 	}

 	/* Copy all the parameters into the buffer */

 	if (ParamSize)

 	{

 		Write_Copy_Params(jit, RetInMemory, RetSize, ParamSize);

 	}

 	/* Push the parameters into the handler */

 	Write_Push_Params(jit, !RetSize, !ParamSize, RetSize, ParamSize, pWrapper);

 	/* Call the handler function */

 	Write_Call_Handler(jit, pWrapper->GetHandlerAddr());

 	/* Copy back the return value into eax or the hidden return buffer */

 	if (RetSize)

 	{

 		Write_Copy_RetVal(jit, pRetInfo);

 	}

 	/* Write the function epilogue */

 	Write_Function_Epilogue(jit, 

 #if defined PLATFORM_WINDOWS

 		ParamSize + ((RetInMemory) ? sizeof(void *) : 0)

 #elif defined PLATFORM_LINUX || defined PLATFORM_APPLE

 		(RetInMemory) ? sizeof(void *) : 0

 #endif

 	);

 	if (writer.outbase == NULL)

 	{

 		CodeSize = writer.get_outputpos();

 		writer.outbase = (jitcode_t)g_SPEngine->AllocatePageMemory(CodeSize);

 		g_SPEngine->SetReadWrite(writer.outbase);

 		writer.outptr = writer.outbase;

 		g_RegDecoder = 0;

 		goto jit_rewind;

 	}

 	g_SPEngine->SetReadExecute(writer.outbase);

 	return writer.outbase;

 }

 void JIT_FreeHook(void *addr)

 {

 	g_SPEngine->FreePageMemory(addr);

 }

 #endif