q3rally/engine/code/qcommon/vm_interpreted.c

/*
===========================================================================
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 Quake III Arena source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
#include "vm_local.h"

//#define	DEBUG_VM
#ifdef DEBUG_VM
static char	*opnames[256] = {
	"OP_UNDEF", 

	"OP_IGNORE", 

	"OP_BREAK",

	"OP_ENTER",
	"OP_LEAVE",
	"OP_CALL",
	"OP_PUSH",
	"OP_POP",

	"OP_CONST",

	"OP_LOCAL",

	"OP_JUMP",

	//-------------------

	"OP_EQ",
	"OP_NE",

	"OP_LTI",
	"OP_LEI",
	"OP_GTI",
	"OP_GEI",

	"OP_LTU",
	"OP_LEU",
	"OP_GTU",
	"OP_GEU",

	"OP_EQF",
	"OP_NEF",

	"OP_LTF",
	"OP_LEF",
	"OP_GTF",
	"OP_GEF",

	//-------------------

	"OP_LOAD1",
	"OP_LOAD2",
	"OP_LOAD4",
	"OP_STORE1",
	"OP_STORE2",
	"OP_STORE4",
	"OP_ARG",

	"OP_BLOCK_COPY",

	//-------------------

	"OP_SEX8",
	"OP_SEX16",

	"OP_NEGI",
	"OP_ADD",
	"OP_SUB",
	"OP_DIVI",
	"OP_DIVU",
	"OP_MODI",
	"OP_MODU",
	"OP_MULI",
	"OP_MULU",

	"OP_BAND",
	"OP_BOR",
	"OP_BXOR",
	"OP_BCOM",

	"OP_LSH",
	"OP_RSHI",
	"OP_RSHU",

	"OP_NEGF",
	"OP_ADDF",
	"OP_SUBF",
	"OP_DIVF",
	"OP_MULF",

	"OP_CVIF",
	"OP_CVFI"
};
#endif

#if idppc

//FIXME: these, um... look the same to me
#if defined(__GNUC__)
static ID_INLINE unsigned int loadWord(void *addr) {
	unsigned int word;

	asm("lwbrx %0,0,%1" : "=r" (word) : "r" (addr));
	return word;
}
#else
static ID_INLINE unsigned int __lwbrx(register void *addr,
		register int offset) {
	register unsigned int word;

	asm("lwbrx %0,%2,%1" : "=r" (word) : "r" (addr), "b" (offset));
	return word;
}
#define loadWord(addr) __lwbrx(addr,0)
#endif

#else
    static ID_INLINE int loadWord(void *addr) {
	int word;
	memcpy(&word, addr, 4);
	return LittleLong(word);
    }
#endif

char *VM_Indent( vm_t *vm ) {
	static char	*string = "                                        ";
	if ( vm->callLevel > 20 ) {
		return string;
	}
	return string + 2 * ( 20 - vm->callLevel );
}

void VM_StackTrace( vm_t *vm, int programCounter, int programStack ) {
	int		count;

	count = 0;
	do {
		Com_Printf( "%s\n", VM_ValueToSymbol( vm, programCounter ) );
		programStack =  *(int *)&vm->dataBase[programStack+4];
		programCounter = *(int *)&vm->dataBase[programStack];
	} while ( programCounter != -1 && ++count < 32 );

}


/*
====================
VM_PrepareInterpreter
====================
*/
void VM_PrepareInterpreter( vm_t *vm, vmHeader_t *header ) {
	int		op;
	int		byte_pc;
	int		int_pc;
	byte	*code;
	int		instruction;
	int		*codeBase;

	vm->codeBase = Hunk_Alloc( vm->codeLength*4, h_high );			// we're now int aligned
//	memcpy( vm->codeBase, (byte *)header + header->codeOffset, vm->codeLength );

	// we don't need to translate the instructions, but we still need
	// to find each instructions starting point for jumps
	int_pc = byte_pc = 0;
	instruction = 0;
	code = (byte *)header + header->codeOffset;
	codeBase = (int *)vm->codeBase;

	// Copy and expand instructions to words while building instruction table
	while ( instruction < header->instructionCount ) {
		vm->instructionPointers[ instruction ] = int_pc;
		instruction++;

		op = (int)code[ byte_pc ];
		codeBase[int_pc] = op;
		if(byte_pc > header->codeLength)
			Com_Error(ERR_DROP, "VM_PrepareInterpreter: pc > header->codeLength");

		byte_pc++;
		int_pc++;

		// these are the only opcodes that aren't a single byte
		switch ( op ) {
		case OP_ENTER:
		case OP_CONST:
		case OP_LOCAL:
		case OP_LEAVE:
		case OP_EQ:
		case OP_NE:
		case OP_LTI:
		case OP_LEI:
		case OP_GTI:
		case OP_GEI:
		case OP_LTU:
		case OP_LEU:
		case OP_GTU:
		case OP_GEU:
		case OP_EQF:
		case OP_NEF:
		case OP_LTF:
		case OP_LEF:
		case OP_GTF:
		case OP_GEF:
		case OP_BLOCK_COPY:
			codeBase[int_pc] = loadWord(&code[byte_pc]);
			byte_pc += 4;
			int_pc++;
			break;
		case OP_ARG:
			codeBase[int_pc] = (int)code[byte_pc];
			byte_pc++;
			int_pc++;
			break;
		default:
			break;
		}

	}
	int_pc = 0;
	instruction = 0;
	
	// Now that the code has been expanded to int-sized opcodes, we'll translate instruction index
	//into an index into codeBase[], which contains opcodes and operands.
	while ( instruction < header->instructionCount ) {
		op = codeBase[ int_pc ];
		instruction++;
		int_pc++;
		
		switch ( op ) {
		// These ops need to translate addresses in jumps from instruction index to int index
		case OP_EQ:
		case OP_NE:
		case OP_LTI:
		case OP_LEI:
		case OP_GTI:
		case OP_GEI:
		case OP_LTU:
		case OP_LEU:
		case OP_GTU:
		case OP_GEU:
		case OP_EQF:
		case OP_NEF:
		case OP_LTF:
		case OP_LEF:
		case OP_GTF:
		case OP_GEF:
			if(codeBase[int_pc] < 0 || codeBase[int_pc] > vm->instructionCount)
				Com_Error(ERR_DROP, "VM_PrepareInterpreter: Jump to invalid instruction number");

			// codeBase[pc] is the instruction index. Convert that into an offset into
			//the int-aligned codeBase[] by the lookup table.
			codeBase[int_pc] = vm->instructionPointers[codeBase[int_pc]];
			int_pc++;
			break;

		// These opcodes have an operand that isn't an instruction index
		case OP_ENTER:
		case OP_CONST:
		case OP_LOCAL:
		case OP_LEAVE:
		case OP_BLOCK_COPY:
		case OP_ARG:
			int_pc++;
			break;

		default:
			break;
		}

	}
}

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


Upon a system call, the stack will look like:

sp+32	parm1
sp+28	parm0
sp+24	return stack
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	DEBUGSTR va("%s%i", VM_Indent(vm), opStackOfs)

int	VM_CallInterpreted( vm_t *vm, int *args ) {
	byte		stack[OPSTACK_SIZE + 15];
	int		*opStack;
	uint8_t 	opStackOfs;
	int		programCounter;
	int		programStack;
	int		stackOnEntry;
	byte	*image;
	int		*codeImage;
	int		v1;
	int		dataMask;
	int		arg;
#ifdef DEBUG_VM
	vmSymbol_t	*profileSymbol;
#endif

	// interpret the code
	vm->currentlyInterpreting = qtrue;

	// we might be called recursively, so this might not be the very top
	programStack = stackOnEntry = vm->programStack;

#ifdef DEBUG_VM
	profileSymbol = VM_ValueToFunctionSymbol( vm, 0 );
	// uncomment this for debugging breakpoints
	vm->breakFunction = 0;
#endif
	// set up the stack frame 

	image = vm->dataBase;
	codeImage = (int *)vm->codeBase;
	dataMask = vm->dataMask;
	
	programCounter = 0;

	programStack -= ( 8 + 4 * MAX_VMMAIN_ARGS );

	for ( arg = 0; arg < MAX_VMMAIN_ARGS; arg++ )
		*(int *)&image[ programStack + 8 + arg * 4 ] = args[ arg ];

	*(int *)&image[ programStack + 4 ] = 0;	// return stack
	*(int *)&image[ programStack ] = -1;	// will terminate the loop on return

	VM_Debug(0);

	// leave a free spot at start of stack so
	// that as long as opStack is valid, opStack-1 will
	// not corrupt anything
	opStack = PADP(stack, 16);
	*opStack = 0xDEADBEEF;
	opStackOfs = 0;

//	vm_debugLevel=2;
	// main interpreter loop, will exit when a LEAVE instruction
	// grabs the -1 program counter

#define r2 codeImage[programCounter]

	while ( 1 ) {
		int		opcode,	r0, r1;
//		unsigned int	r2;

nextInstruction:
		r0 = opStack[opStackOfs];
		r1 = opStack[(uint8_t) (opStackOfs - 1)];
nextInstruction2:
#ifdef DEBUG_VM
		if ( (unsigned)programCounter >= vm->codeLength ) {
			Com_Error( ERR_DROP, "VM pc out of range" );
			return 0;
		}

		if ( programStack <= vm->stackBottom ) {
			Com_Error( ERR_DROP, "VM stack overflow" );
			return 0;
		}

		if ( programStack & 3 ) {
			Com_Error( ERR_DROP, "VM program stack misaligned" );
			return 0;
		}

		if ( vm_debugLevel > 1 ) {
			Com_Printf( "%s %s\n", DEBUGSTR, opnames[opcode] );
		}
		profileSymbol->profileCount++;
#endif
		opcode = codeImage[ programCounter++ ];

		switch ( opcode ) {
#ifdef DEBUG_VM
		default:
			Com_Error( ERR_DROP, "Bad VM instruction" );  // this should be scanned on load!
			return 0;
#endif
		case OP_BREAK:
			vm->breakCount++;
			goto nextInstruction2;
		case OP_CONST:
			opStackOfs++;
			r1 = r0;
			r0 = opStack[opStackOfs] = r2;
			
			programCounter += 1;
			goto nextInstruction2;
		case OP_LOCAL:
			opStackOfs++;
			r1 = r0;
			r0 = opStack[opStackOfs] = r2+programStack;

			programCounter += 1;
			goto nextInstruction2;

		case OP_LOAD4:
#ifdef DEBUG_VM
			if(opStack[opStackOfs] & 3)
			{
				Com_Error( ERR_DROP, "OP_LOAD4 misaligned" );
				return 0;
			}
#endif
			r0 = opStack[opStackOfs] = *(int *) &image[ r0 & dataMask ];
			goto nextInstruction2;
		case OP_LOAD2:
			r0 = opStack[opStackOfs] = *(unsigned short *)&image[ r0 & dataMask ];
			goto nextInstruction2;
		case OP_LOAD1:
			r0 = opStack[opStackOfs] = image[ r0 & dataMask ];
			goto nextInstruction2;

		case OP_STORE4:
			*(int *)&image[ r1 & dataMask ] = r0;
			opStackOfs -= 2;
			goto nextInstruction;
		case OP_STORE2:
			*(short *)&image[ r1 & dataMask ] = r0;
			opStackOfs -= 2;
			goto nextInstruction;
		case OP_STORE1:
			image[ r1 & dataMask ] = r0;
			opStackOfs -= 2;
			goto nextInstruction;

		case OP_ARG:
			// single byte offset from programStack
			*(int *)&image[ (codeImage[programCounter] + programStack) & dataMask ] = r0;
			opStackOfs--;
			programCounter += 1;
			goto nextInstruction;

		case OP_BLOCK_COPY:
			VM_BlockCopy(r1, r0, r2);
			programCounter += 1;
			opStackOfs -= 2;
			goto nextInstruction;

		case OP_CALL:
			// save current program counter
			*(int *)&image[ programStack ] = programCounter;
			
			// jump to the location on the stack
			programCounter = r0;
			opStackOfs--;
			if ( programCounter < 0 ) {
				// system call
				int		r;
//				int		temp;
#ifdef DEBUG_VM
				int		stomped;

				if ( vm_debugLevel ) {
					Com_Printf( "%s---> systemcall(%i)\n", DEBUGSTR, -1 - programCounter );
				}
#endif
				// save the stack to allow recursive VM entry
//				temp = vm->callLevel;
				vm->programStack = programStack - 4;
#ifdef DEBUG_VM
				stomped = *(int *)&image[ programStack + 4 ];
#endif
				*(int *)&image[ programStack + 4 ] = -1 - programCounter;

//VM_LogSyscalls( (int *)&image[ programStack + 4 ] );
				{
					// the vm has ints on the stack, we expect
					// pointers so we might have to convert it
					if (sizeof(intptr_t) != sizeof(int)) {
						intptr_t argarr[ MAX_VMSYSCALL_ARGS ];
						int *imagePtr = (int *)&image[ programStack ];
						int i;
						for (i = 0; i < ARRAY_LEN(argarr); ++i) {
							argarr[i] = *(++imagePtr);
						}
						r = vm->systemCall( argarr );
					} else {
						intptr_t* argptr = (intptr_t *)&image[ programStack + 4 ];
						r = vm->systemCall( argptr );
					}
				}

#ifdef DEBUG_VM
				// this is just our stack frame pointer, only needed
				// for debugging
				*(int *)&image[ programStack + 4 ] = stomped;
#endif

				// save return value
				opStackOfs++;
				opStack[opStackOfs] = r;
				programCounter = *(int *)&image[ programStack ];
//				vm->callLevel = temp;
#ifdef DEBUG_VM
				if ( vm_debugLevel ) {
					Com_Printf( "%s<--- %s\n", DEBUGSTR, VM_ValueToSymbol( vm, programCounter ) );
				}
#endif
			} else if ( (unsigned)programCounter >= vm->instructionCount ) {
				Com_Error( ERR_DROP, "VM program counter out of range in OP_CALL" );
				return 0;
			} else {
				programCounter = vm->instructionPointers[ programCounter ];
			}
			goto nextInstruction;

		// push and pop are only needed for discarded or bad function return values
		case OP_PUSH:
			opStackOfs++;
			goto nextInstruction;
		case OP_POP:
			opStackOfs--;
			goto nextInstruction;

		case OP_ENTER:
#ifdef DEBUG_VM
			profileSymbol = VM_ValueToFunctionSymbol( vm, programCounter );
#endif
			// get size of stack frame
			v1 = r2;

			programCounter += 1;
			programStack -= v1;
#ifdef DEBUG_VM
			// save old stack frame for debugging traces
			*(int *)&image[programStack+4] = programStack + v1;
			if ( vm_debugLevel ) {
				Com_Printf( "%s---> %s\n", DEBUGSTR, VM_ValueToSymbol( vm, programCounter - 5 ) );
				if ( vm->breakFunction && programCounter - 5 == vm->breakFunction ) {
					// this is to allow setting breakpoints here in the debugger
					vm->breakCount++;
//					vm_debugLevel = 2;
//					VM_StackTrace( vm, programCounter, programStack );
				}
//				vm->callLevel++;
			}
#endif
			goto nextInstruction;
		case OP_LEAVE:
			// remove our stack frame
			v1 = r2;

			programStack += v1;

			// grab the saved program counter
			programCounter = *(int *)&image[ programStack ];
#ifdef DEBUG_VM
			profileSymbol = VM_ValueToFunctionSymbol( vm, programCounter );
			if ( vm_debugLevel ) {
//				vm->callLevel--;
				Com_Printf( "%s<--- %s\n", DEBUGSTR, VM_ValueToSymbol( vm, programCounter ) );
			}
#endif
			// check for leaving the VM
			if ( programCounter == -1 ) {
				goto done;
			} else if ( (unsigned)programCounter >= vm->codeLength ) {
				Com_Error( ERR_DROP, "VM program counter out of range in OP_LEAVE" );
				return 0;
			}
			goto nextInstruction;

		/*
		===================================================================
		BRANCHES
		===================================================================
		*/

		case OP_JUMP:
			if ( (unsigned)r0 >= vm->instructionCount )
			{
				Com_Error( ERR_DROP, "VM program counter out of range in OP_JUMP" );
				return 0;
			}

			programCounter = vm->instructionPointers[ r0 ];

			opStackOfs--;
			goto nextInstruction;

		case OP_EQ:
			opStackOfs -= 2;
			if ( r1 == r0 ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_NE:
			opStackOfs -= 2;
			if ( r1 != r0 ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_LTI:
			opStackOfs -= 2;
			if ( r1 < r0 ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_LEI:
			opStackOfs -= 2;
			if ( r1 <= r0 ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_GTI:
			opStackOfs -= 2;
			if ( r1 > r0 ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_GEI:
			opStackOfs -= 2;
			if ( r1 >= r0 ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_LTU:
			opStackOfs -= 2;
			if ( ((unsigned)r1) < ((unsigned)r0) ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_LEU:
			opStackOfs -= 2;
			if ( ((unsigned)r1) <= ((unsigned)r0) ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_GTU:
			opStackOfs -= 2;
			if ( ((unsigned)r1) > ((unsigned)r0) ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_GEU:
			opStackOfs -= 2;
			if ( ((unsigned)r1) >= ((unsigned)r0) ) {
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_EQF:
			opStackOfs -= 2;
			
			if(((float *) opStack)[(uint8_t) (opStackOfs + 1)] == ((float *) opStack)[(uint8_t) (opStackOfs + 2)])
			{
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_NEF:
			opStackOfs -= 2;

			if(((float *) opStack)[(uint8_t) (opStackOfs + 1)] != ((float *) opStack)[(uint8_t) (opStackOfs + 2)])
			{
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_LTF:
			opStackOfs -= 2;

			if(((float *) opStack)[(uint8_t) (opStackOfs + 1)] < ((float *) opStack)[(uint8_t) (opStackOfs + 2)])
			{
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_LEF:
			opStackOfs -= 2;

			if(((float *) opStack)[(uint8_t) ((uint8_t) (opStackOfs + 1))] <= ((float *) opStack)[(uint8_t) ((uint8_t) (opStackOfs + 2))])
			{
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_GTF:
			opStackOfs -= 2;

			if(((float *) opStack)[(uint8_t) (opStackOfs + 1)] > ((float *) opStack)[(uint8_t) (opStackOfs + 2)])
			{
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}

		case OP_GEF:
			opStackOfs -= 2;

			if(((float *) opStack)[(uint8_t) (opStackOfs + 1)] >= ((float *) opStack)[(uint8_t) (opStackOfs + 2)])
			{
				programCounter = r2;	//vm->instructionPointers[r2];
				goto nextInstruction;
			} else {
				programCounter += 1;
				goto nextInstruction;
			}


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

		case OP_NEGI:
			opStack[opStackOfs] = -r0;
			goto nextInstruction;
		case OP_ADD:
			opStackOfs--;
			opStack[opStackOfs] = r1 + r0;
			goto nextInstruction;
		case OP_SUB:
			opStackOfs--;
			opStack[opStackOfs] = r1 - r0;
			goto nextInstruction;
		case OP_DIVI:
			opStackOfs--;
			opStack[opStackOfs] = r1 / r0;
			goto nextInstruction;
		case OP_DIVU:
			opStackOfs--;
			opStack[opStackOfs] = ((unsigned) r1) / ((unsigned) r0);
			goto nextInstruction;
		case OP_MODI:
			opStackOfs--;
			opStack[opStackOfs] = r1 % r0;
			goto nextInstruction;
		case OP_MODU:
			opStackOfs--;
			opStack[opStackOfs] = ((unsigned) r1) % ((unsigned) r0);
			goto nextInstruction;
		case OP_MULI:
			opStackOfs--;
			opStack[opStackOfs] = r1 * r0;
			goto nextInstruction;
		case OP_MULU:
			opStackOfs--;
			opStack[opStackOfs] = ((unsigned) r1) * ((unsigned) r0);
			goto nextInstruction;

		case OP_BAND:
			opStackOfs--;
			opStack[opStackOfs] = ((unsigned) r1) & ((unsigned) r0);
			goto nextInstruction;
		case OP_BOR:
			opStackOfs--;
			opStack[opStackOfs] = ((unsigned) r1) | ((unsigned) r0);
			goto nextInstruction;
		case OP_BXOR:
			opStackOfs--;
			opStack[opStackOfs] = ((unsigned) r1) ^ ((unsigned) r0);
			goto nextInstruction;
		case OP_BCOM:
			opStack[opStackOfs] = ~((unsigned) r0);
			goto nextInstruction;

		case OP_LSH:
			opStackOfs--;
			opStack[opStackOfs] = r1 << r0;
			goto nextInstruction;
		case OP_RSHI:
			opStackOfs--;
			opStack[opStackOfs] = r1 >> r0;
			goto nextInstruction;
		case OP_RSHU:
			opStackOfs--;
			opStack[opStackOfs] = ((unsigned) r1) >> r0;
			goto nextInstruction;

		case OP_NEGF:
			((float *) opStack)[opStackOfs] =  -((float *) opStack)[opStackOfs];
			goto nextInstruction;
		case OP_ADDF:
			opStackOfs--;
			((float *) opStack)[opStackOfs] = ((float *) opStack)[opStackOfs] + ((float *) opStack)[(uint8_t) (opStackOfs + 1)];
			goto nextInstruction;
		case OP_SUBF:
			opStackOfs--;
			((float *) opStack)[opStackOfs] = ((float *) opStack)[opStackOfs] - ((float *) opStack)[(uint8_t) (opStackOfs + 1)];
			goto nextInstruction;
		case OP_DIVF:
			opStackOfs--;
			((float *) opStack)[opStackOfs] = ((float *) opStack)[opStackOfs] / ((float *) opStack)[(uint8_t) (opStackOfs + 1)];
			goto nextInstruction;
		case OP_MULF:
			opStackOfs--;
			((float *) opStack)[opStackOfs] = ((float *) opStack)[opStackOfs] * ((float *) opStack)[(uint8_t) (opStackOfs + 1)];
			goto nextInstruction;

		case OP_CVIF:
			((float *) opStack)[opStackOfs] = (float) opStack[opStackOfs];
			goto nextInstruction;
		case OP_CVFI:
			opStack[opStackOfs] = Q_ftol(((float *) opStack)[opStackOfs]);
			goto nextInstruction;
		case OP_SEX8:
			opStack[opStackOfs] = (signed char) opStack[opStackOfs];
			goto nextInstruction;
		case OP_SEX16:
			opStack[opStackOfs] = (short) opStack[opStackOfs];
			goto nextInstruction;
		}
	}

done:
	vm->currentlyInterpreting = qfalse;

	if (opStackOfs != 1 || *opStack != 0xDEADBEEF)
		Com_Error(ERR_DROP, "Interpreter error: opStack[0] = %X, opStackOfs = %d", opStack[0], opStackOfs);

	vm->programStack = stackOnEntry;

	// return the result
	return opStack[opStackOfs];
}