/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena source code 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.

Quake III Arena source code 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 Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
// vm.c -- virtual machine

/*


intermix code and data
symbol table

a dll has one imported function: VM_SystemCall
and one exported function: Perform


*/

#include "vm_local.h"


vm_t	*currentVM = NULL; // bk001212
vm_t	*lastVM    = NULL; // bk001212
int		vm_debugLevel;

#define	MAX_VM		3
vm_t	vmTable[MAX_VM];


void VM_VmInfo_f( void );
void VM_VmProfile_f( void );

void VM_Debug( int level ) {
	vm_debugLevel = level;
}

/*
==============
VM_Init
==============
*/
void VM_Init( void ) {
	Cvar_Get( "vm_cgame", "2", CVAR_ARCHIVE );	// !@# SHIP WITH SET TO 2
	Cvar_Get( "vm_game", "2", CVAR_ARCHIVE );	// !@# SHIP WITH SET TO 2
	Cvar_Get( "vm_ui", "2", CVAR_ARCHIVE );		// !@# SHIP WITH SET TO 2

	Cmd_AddCommand ("vmprofile", VM_VmProfile_f );
	Cmd_AddCommand ("vminfo", VM_VmInfo_f );

	Com_Memset( vmTable, 0, sizeof( vmTable ) );
}


/*
===============
VM_ValueToSymbol

Assumes a program counter value
===============
*/
const char *VM_ValueToSymbol( vm_t *vm, int value ) {
	vmSymbol_t	*sym;
	static char		text[MAX_TOKEN_CHARS];

	sym = vm->symbols;
	if ( !sym ) {
		return "NO SYMBOLS";
	}

	// find the symbol
	while ( sym->next && sym->next->symValue <= value ) {
		sym = sym->next;
	}

	if ( value == sym->symValue ) {
		return sym->symName;
	}

	Com_sprintf( text, sizeof( text ), "%s+%i", sym->symName, value - sym->symValue );

	return text;
}

/*
===============
VM_ValueToFunctionSymbol

For profiling, find the symbol behind this value
===============
*/
vmSymbol_t *VM_ValueToFunctionSymbol( vm_t *vm, int value ) {
	vmSymbol_t	*sym;
	static vmSymbol_t	nullSym;

	sym = vm->symbols;
	if ( !sym ) {
		return &nullSym;
	}

	while ( sym->next && sym->next->symValue <= value ) {
		sym = sym->next;
	}

	return sym;
}


/*
===============
VM_SymbolToValue
===============
*/
int VM_SymbolToValue( vm_t *vm, const char *symbol ) {
	vmSymbol_t	*sym;

	for ( sym = vm->symbols ; sym ; sym = sym->next ) {
		if ( !strcmp( symbol, sym->symName ) ) {
			return sym->symValue;
		}
	}
	return 0;
}

/*
===============
ParseHex
===============
*/
int	ParseHex( const char *text ) {
	int		value;
	int		c;

	value = 0;
	while ( ( c = *text++ ) != 0 ) {
		if ( c >= '0' && c <= '9' ) {
			value = value * 16 + c - '0';
			continue;
		}
		if ( c >= 'a' && c <= 'f' ) {
			value = value * 16 + 10 + c - 'a';
			continue;
		}
		if ( c >= 'A' && c <= 'F' ) {
			value = value * 16 + 10 + c - 'A';
			continue;
		}
	}

	return value;
}

/*
===============
VM_LoadSymbols
===============
*/
void VM_LoadSymbols( vm_t *vm ) {
	int		len;
	char	*mapfile, *text_p, *token;
	char	name[MAX_QPATH];
	char	symbols[MAX_QPATH];
	vmSymbol_t	**prev, *sym;
	int		count;
	int		value;
	int		chars;
	int		segment;
	int		numInstructions;

	// don't load symbols if not developer
	if ( !com_developer->integer ) {
		return;
	}

	COM_StripExtension( vm->name, name );
	Com_sprintf( symbols, sizeof( symbols ), "vm/%s.map", name );
	len = FS_ReadFile( symbols, (void **)&mapfile );
	if ( !mapfile ) {
		Com_Printf( "Couldn't load symbol file: %s\n", symbols );
		return;
	}

	numInstructions = vm->instructionPointersLength >> 2;

	// parse the symbols
	text_p = mapfile;
	prev = &vm->symbols;
	count = 0;

	while ( 1 ) {
		token = COM_Parse( &text_p );
		if ( !token[0] ) {
			break;
		}
		segment = ParseHex( token );
		if ( segment ) {
			COM_Parse( &text_p );
			COM_Parse( &text_p );
			continue;		// only load code segment values
		}

		token = COM_Parse( &text_p );
		if ( !token[0] ) {
			Com_Printf( "WARNING: incomplete line at end of file\n" );
			break;
		}
		value = ParseHex( token );

		token = COM_Parse( &text_p );
		if ( !token[0] ) {
			Com_Printf( "WARNING: incomplete line at end of file\n" );
			break;
		}
		chars = (int)strlen( token );
		sym = Hunk_Alloc( sizeof( *sym ) + chars, h_high );
		*prev = sym;
		prev = &sym->next;
		sym->next = NULL;

		// convert value from an instruction number to a code offset
		if ( value >= 0 && value < numInstructions ) {
			value = vm->instructionPointers[value];
		}

		sym->symValue = value;
		Q_strncpyz( sym->symName, token, chars + 1 );

		count++;
	}

	vm->numSymbols = count;
	Com_Printf( "%i symbols parsed from %s\n", count, symbols );
	FS_FreeFile( mapfile );
}

intptr_t QDECL VM_DllSyscall( intptr_t arg, ... ) {
  intptr_t args[MAX_VMSYSCALL_ARGS];
  int i;
  va_list ap;

  args[0] = arg;
  
  va_start(ap, arg);
  for (i = 1; i < ARRAY_LEN(args); i++)
    args[i] = va_arg(ap, intptr_t);
  va_end(ap);
  
  return currentVM->systemCall( args );
}

/*
=================
VM_Restart

Reload the data, but leave everything else in place
This allows a server to do a map_restart without changing memory allocation
=================
*/
vm_t *VM_Restart( vm_t *vm ) {
	vmHeader_t	*header;
	int			length;
	int			dataLength;
	int			i;
	char		filename[MAX_QPATH];

	// DLL's can't be restarted in place
	if ( vm->dllHandle ) {
		char	name[MAX_QPATH];
	    intptr_t (*systemCall)( intptr_t *parms );
		
		systemCall = vm->systemCall;	
		Q_strncpyz( name, vm->name, sizeof( name ) );

		VM_Free( vm );

		vm = VM_Create( name, systemCall, VMI_NATIVE );
		return vm;
	}

	// load the image
	Com_Printf( "VM_Restart()\n", filename );
	Com_sprintf( filename, sizeof(filename), "vm/%s.qvm", vm->name );
	Com_Printf( "Loading vm file %s.\n", filename );
	length = FS_ReadFile( filename, (void **)&header );
	if ( !header ) {
		Com_Error( ERR_DROP, "VM_Restart failed.\n" );
	}

	// byte swap the header
	for ( i = 0 ; i < sizeof( *header ) / 4 ; i++ ) {
		((int *)header)[i] = LittleLong( ((int *)header)[i] );
	}

	// validate
	if ( header->vmMagic != VM_MAGIC
		|| header->bssLength < 0 
		|| header->dataLength < 0 
		|| header->litLength < 0 
		|| header->codeLength <= 0 ) {
		VM_Free( vm );
		Com_Error( ERR_FATAL, "%s has bad header", filename );
	}

	// round up to next power of 2 so all data operations can
	// be mask protected
	dataLength = header->dataLength + header->litLength + header->bssLength;
	for ( i = 0 ; dataLength > ( 1 << i ) ; i++ ) {
	}
	dataLength = 1 << i;

	// clear the data
	Com_Memset( vm->dataBase, 0, dataLength );

	// copy the intialized data
	Com_Memcpy( vm->dataBase, (byte *)header + header->dataOffset, header->dataLength + header->litLength );

	// byte swap the longs
	for ( i = 0 ; i < header->dataLength ; i += 4 ) {
		*(int *)(vm->dataBase + i) = LittleLong( *(int *)(vm->dataBase + i ) );
	}

	// free the original file
	FS_FreeFile( header );

	return vm;
}

/*
================
VM_Create

If image ends in .qvm it will be interpreted, otherwise
it will attempt to load as a system dll
================
*/

#define	STACK_SIZE	0x20000

vm_t *VM_Create( const char *module, intptr_t (*systemCalls)(intptr_t *), 
				vmInterpret_t interpret ) {
	vm_t		*vm;
	vmHeader_t	*header;
	int			length;
	int			dataLength;
	int			i, remaining;
	char		filename[MAX_QPATH];

	if ( !module || !module[0] || !systemCalls ) {
		Com_Error( ERR_FATAL, "VM_Create: bad parms" );
	}

	remaining = Hunk_MemoryRemaining();

	// see if we already have the VM
	for ( i = 0 ; i < MAX_VM ; i++ ) {
		if (!Q_stricmp(vmTable[i].name, module)) {
			vm = &vmTable[i];
			return vm;
		}
	}

	// find a free vm
	for ( i = 0 ; i < MAX_VM ; i++ ) {
		if ( !vmTable[i].name[0] ) {
			break;
		}
	}

	if ( i == MAX_VM ) {
		Com_Error( ERR_FATAL, "VM_Create: no free vm_t" );
	}

	vm = &vmTable[i];

	Q_strncpyz( vm->name, module, sizeof( vm->name ) );
	vm->systemCall = systemCalls;

	// never allow dll loading with a demo
	if ( interpret == VMI_NATIVE ) {
		if ( Cvar_VariableValue( "fs_restrict" ) ) {
			interpret = VMI_COMPILED;
		}
	}

	if ( interpret == VMI_NATIVE ) {
		// try to load as a system dll
		Com_Printf( "Loading dll file %s.\n", vm->name );
		vm->dllHandle = Sys_LoadDll( module, vm->fqpath , &vm->entryPoint, VM_DllSyscall );
		if ( vm->dllHandle ) {
			return vm;
		}

		Com_Printf( "Failed to load dll, looking for qvm.\n" );
		interpret = VMI_COMPILED;
	}

	// load the image
	Com_sprintf( filename, sizeof(filename), "vm/%s.qvm", vm->name );
	Com_Printf( "Loading vm file %s.\n", filename );
	length = FS_ReadFile( filename, (void **)&header );
	if ( !header ) {
		Com_Printf( "Failed.\n" );
		VM_Free( vm );
		return NULL;
	}

	// byte swap the header
	for ( i = 0 ; i < sizeof( *header ) / 4 ; i++ ) {
		((int *)header)[i] = LittleLong( ((int *)header)[i] );
	}

	// validate
	if ( header->vmMagic != VM_MAGIC
		|| header->bssLength < 0 
		|| header->dataLength < 0 
		|| header->litLength < 0 
		|| header->codeLength <= 0 ) {
		VM_Free( vm );
		Com_Error( ERR_FATAL, "%s has bad header", filename );
	}

	// round up to next power of 2 so all data operations can
	// be mask protected
	dataLength = header->dataLength + header->litLength + header->bssLength;
	for ( i = 0 ; dataLength > ( 1 << i ) ; i++ ) {
	}
	dataLength = 1 << i;

	// allocate zero filled space for initialized and uninitialized data
	vm->dataBase = Hunk_Alloc( dataLength, h_high );
	vm->dataMask = dataLength - 1;

	// copy the intialized data
	Com_Memcpy( vm->dataBase, (byte *)header + header->dataOffset, header->dataLength + header->litLength );

	// byte swap the longs
	for ( i = 0 ; i < header->dataLength ; i += 4 ) {
		*(int *)(vm->dataBase + i) = LittleLong( *(int *)(vm->dataBase + i ) );
	}

	// allocate space for the jump targets, which will be filled in by the compile/prep functions
	vm->instructionPointersLength = header->instructionCount * 4;
	vm->instructionPointers = Hunk_Alloc( vm->instructionPointersLength, h_high );

	// copy or compile the instructions
	vm->codeLength = header->codeLength;

#ifdef _WIN64
	vm->compiled = qfalse;
	VM_PrepareInterpreter( vm, header );
#else
	if ( interpret >= VMI_COMPILED ) {
		vm->compiled = qtrue;
		VM_Compile( vm, header );
	} else {
		vm->compiled = qfalse;
		VM_PrepareInterpreter( vm, header );
	}
#endif

	// free the original file
	FS_FreeFile( header );

	// load the map file
	VM_LoadSymbols( vm );

	// the stack is implicitly at the end of the image
	vm->programStack = vm->dataMask + 1;
	vm->stackBottom = vm->programStack - STACK_SIZE;

	Com_Printf("%s loaded in %d bytes on the hunk\n", module, remaining - Hunk_MemoryRemaining());

	return vm;
}

/*
==============
VM_Free
==============
*/
void VM_Free( vm_t *vm ) {

	if ( vm->dllHandle ) {
		Sys_UnloadDll( vm->dllHandle );
		Com_Memset( vm, 0, sizeof( *vm ) );
	}
#if 0	// now automatically freed by hunk
	if ( vm->codeBase ) {
		Z_Free( vm->codeBase );
	}
	if ( vm->dataBase ) {
		Z_Free( vm->dataBase );
	}
	if ( vm->instructionPointers ) {
		Z_Free( vm->instructionPointers );
	}
#endif
	Com_Memset( vm, 0, sizeof( *vm ) );

	currentVM = NULL;
	lastVM = NULL;
}

void VM_Clear(void) {
	int i;
	for (i=0;i<MAX_VM; i++) {
		if ( vmTable[i].dllHandle ) {
			Sys_UnloadDll( vmTable[i].dllHandle );
		}
		Com_Memset( &vmTable[i], 0, sizeof( vm_t ) );
	}
	currentVM = NULL;
	lastVM = NULL;
}

void *VM_ArgPtr( intptr_t intValue ) {
	if ( !intValue ) {
		return NULL;
	}
	// bk001220 - currentVM is missing on reconnect
	if ( currentVM==NULL )
	  return NULL;

	if ( currentVM->entryPoint ) {
		return (void *)(currentVM->dataBase + intValue);
	}
	else {
		return (void *)(currentVM->dataBase + (intValue & currentVM->dataMask));
	}
}

void *VM_ExplicitArgPtr( vm_t *vm, intptr_t intValue ) {
	if ( !intValue ) {
		return NULL;
	}

	// bk010124 - currentVM is missing on reconnect here as well?
	if ( currentVM==NULL )
	  return NULL;

	//
	if ( vm->entryPoint ) {
		return (void *)(vm->dataBase + intValue);
	}
	else {
		return (void *)(vm->dataBase + (intValue & vm->dataMask));
	}
}


/*
==============
VM_Call


Upon a system call, the stack will look like:

sp+32	parm1
sp+28	parm0
sp+24	return value
sp+20	return address
sp+16	local1
sp+14	local0
sp+12	arg1
sp+8	arg0
sp+4	return stack
sp		return address

An interpreted function will immediately execute
an OP_ENTER instruction, which will subtract space for
locals from sp
==============
*/
#define	MAX_STACK	256
#define	STACK_MASK	(MAX_STACK-1)

intptr_t	QDECL VM_Call( vm_t *vm, int callnum, ... ) {
	vm_t	*oldVM;
	intptr_t		r;
	int i;
	int args[16];
	va_list ap;


	if ( !vm ) {
		Com_Error( ERR_FATAL, "VM_Call with NULL vm" );
	}

	oldVM = currentVM;
	currentVM = vm;
	lastVM = vm;

	if ( vm_debugLevel ) {
	  Com_Printf( "VM_Call( %i )\n", callnum );
	}

	// if we have a dll loaded, call it directly
	if ( vm->entryPoint ) {
		//rcg010207 -  see dissertation at top of VM_DllSyscall() in this file.
		va_start(ap, callnum);
		for (i = 0; i < sizeof (args) / sizeof (args[i]); i++) {
			args[i] = va_arg(ap, int);
		}
		va_end(ap);

		r = vm->entryPoint( callnum,  args[0],  args[1],  args[2], args[3],
                            args[4],  args[5],  args[6], args[7],
                            args[8],  args[9], args[10], args[11],
                            args[12], args[13], args[14], args[15]);
	}
#ifndef _WIN64
	else if ( vm->compiled )
	{
		r = VM_CallCompiled( vm, &callnum );
	}
#endif
	else
	{
		struct {
			int callnum;
			int args[10];
		} a;
		a.callnum = callnum;
		va_start(ap, callnum);
		for (i = 0; i < sizeof (a.args) / sizeof (a.args[i]); i++) {
			a.args[i] = va_arg(ap, int);
		}
		va_end(ap);

		r = VM_CallInterpreted( vm, &a.callnum );
	}

	if ( oldVM != NULL ) // bk001220 - assert(currentVM!=NULL) for oldVM==NULL
	  currentVM = oldVM;
	return r;
}

//=================================================================

static int QDECL VM_ProfileSort( const void *a, const void *b ) {
	vmSymbol_t	*sa, *sb;

	sa = *(vmSymbol_t **)a;
	sb = *(vmSymbol_t **)b;

	if ( sa->profileCount < sb->profileCount ) {
		return -1;
	}
	if ( sa->profileCount > sb->profileCount ) {
		return 1;
	}
	return 0;
}

/*
==============
VM_VmProfile_f

==============
*/
void VM_VmProfile_f( void ) {
	vm_t		*vm;
	vmSymbol_t	**sorted, *sym;
	int			i;
	double		total;

	if ( !lastVM ) {
		return;
	}

	vm = lastVM;

	if ( !vm->numSymbols ) {
		return;
	}

	sorted = Z_Malloc( vm->numSymbols * sizeof( *sorted ) );
	sorted[0] = vm->symbols;
	total = sorted[0]->profileCount;
	for ( i = 1 ; i < vm->numSymbols ; i++ ) {
		sorted[i] = sorted[i-1]->next;
		total += sorted[i]->profileCount;
	}

	qsort( sorted, vm->numSymbols, sizeof( *sorted ), VM_ProfileSort );

	for ( i = 0 ; i < vm->numSymbols ; i++ ) {
		int		perc;

		sym = sorted[i];

		perc = 100 * (float) sym->profileCount / total;
		Com_Printf( "%2i%% %9i %s\n", perc, sym->profileCount, sym->symName );
		sym->profileCount = 0;
	}

	Com_Printf("    %9.0f total\n", total );

	Z_Free( sorted );
}

/*
==============
VM_VmInfo_f

==============
*/
void VM_VmInfo_f( void ) {
	vm_t	*vm;
	int		i;

	Com_Printf( "Registered virtual machines:\n" );
	for ( i = 0 ; i < MAX_VM ; i++ ) {
		vm = &vmTable[i];
		if ( !vm->name[0] ) {
			break;
		}
		Com_Printf( "%s : ", vm->name );
		if ( vm->dllHandle ) {
			Com_Printf( "native\n" );
			continue;
		}
		if ( vm->compiled ) {
			Com_Printf( "compiled on load\n" );
		} else {
			Com_Printf( "interpreted\n" );
		}
		Com_Printf( "    code length : %7i\n", vm->codeLength );
		Com_Printf( "    table length: %7i\n", vm->instructionPointersLength );
		Com_Printf( "    data length : %7i\n", vm->dataMask + 1 );
	}
}

/*
===============
VM_LogSyscalls

Insert calls to this while debugging the vm compiler
===============
*/
void VM_LogSyscalls( int *args ) {
	static	int		callnum;
	static	FILE	*f;

	if ( !f ) {
		f = fopen("syscalls.log", "w" );
	}
	callnum++;
	fprintf(f, "%i: %i (%i) = %i %i %i %i\n", callnum, (int)(intptr_t)( args - (int *)currentVM->dataBase ),
		args[0], args[1], args[2], args[3], args[4] );
}



#ifdef oDLL_ONLY // bk010215 - for DLL_ONLY dedicated servers/builds w/o VM
int	VM_CallCompiled( vm_t *vm, int *args ) {
  return(0); 
}

void VM_Compile( vm_t *vm, vmHeader_t *header ) {}
#endif // DLL_ONLY