/*

** $Id: lopcodes.h,v 1.102 2002/08/21 18:56:09 roberto Exp $

** Opcodes for Lua virtual machine

** See Copyright Notice in lua.h

*/



#ifndef lopcodes_h

#define lopcodes_h



#include "llimits.h"





/*===========================================================================

  We assume that instructions are unsigned numbers.

  All instructions have an opcode in the first 6 bits.

  Instructions can have the following fields:

	`A' : 8 bits

	`B' : 9 bits

	`C' : 9 bits

	`Bx' : 18 bits (`B' and `C' together)

	`sBx' : signed Bx



  A signed argument is represented in excess K; that is, the number

  value is the unsigned value minus K. K is exactly the maximum value

  for that argument (so that -max is represented by 0, and +max is

  represented by 2*max), which is half the maximum for the corresponding

  unsigned argument.

===========================================================================*/





enum OpMode {iABC, iABx, iAsBx};  /* basic instruction format */





/*

** size and position of opcode arguments.

*/

#define SIZE_C		9

#define SIZE_B		9

#define SIZE_Bx		(SIZE_C + SIZE_B)

#define SIZE_A		8



#define SIZE_OP		6



#define POS_C		SIZE_OP

#define POS_B		(POS_C + SIZE_C)

#define POS_Bx		POS_C

#define POS_A		(POS_B + SIZE_B)





/*

** limits for opcode arguments.

** we use (signed) int to manipulate most arguments,

** so they must fit in BITS_INT-1 bits (-1 for sign)

*/

#if SIZE_Bx < BITS_INT-1

#define MAXARG_Bx        ((1<<SIZE_Bx)-1)

#define MAXARG_sBx        (MAXARG_Bx>>1)         /* `sBx' is signed */

#else

#define MAXARG_Bx        MAX_INT

#define MAXARG_sBx        MAX_INT

#endif





#define MAXARG_A        ((1<<SIZE_A)-1)

#define MAXARG_B        ((1<<SIZE_B)-1)

#define MAXARG_C        ((1<<SIZE_C)-1)





/* creates a mask with `n' 1 bits at position `p' */

#define MASK1(n,p)	((~((~(Instruction)0)<<n))<<p)



/* creates a mask with `n' 0 bits at position `p' */

#define MASK0(n,p)	(~MASK1(n,p))



/*

** the following macros help to manipulate instructions

*/



#define GET_OPCODE(i)	(cast(OpCode, (i)&MASK1(SIZE_OP,0)))

#define SET_OPCODE(i,o)	((i) = (((i)&MASK0(SIZE_OP,0)) | cast(Instruction, o)))



#define GETARG_A(i)	(cast(int, (i)>>POS_A))

#define SETARG_A(i,u)	((i) = (((i)&MASK0(SIZE_A,POS_A)) | \

		((cast(Instruction, u)<<POS_A)&MASK1(SIZE_A,POS_A))))



#define GETARG_B(i)	(cast(int, ((i)>>POS_B) & MASK1(SIZE_B,0)))

#define SETARG_B(i,b)	((i) = (((i)&MASK0(SIZE_B,POS_B)) | \

		((cast(Instruction, b)<<POS_B)&MASK1(SIZE_B,POS_B))))



#define GETARG_C(i)	(cast(int, ((i)>>POS_C) & MASK1(SIZE_C,0)))

#define SETARG_C(i,b)	((i) = (((i)&MASK0(SIZE_C,POS_C)) | \

		((cast(Instruction, b)<<POS_C)&MASK1(SIZE_C,POS_C))))



#define GETARG_Bx(i)	(cast(int, ((i)>>POS_Bx) & MASK1(SIZE_Bx,0)))

#define SETARG_Bx(i,b)	((i) = (((i)&MASK0(SIZE_Bx,POS_Bx)) | \

		((cast(Instruction, b)<<POS_Bx)&MASK1(SIZE_Bx,POS_Bx))))



#define GETARG_sBx(i)	(GETARG_Bx(i)-MAXARG_sBx)

#define SETARG_sBx(i,b)	SETARG_Bx((i),cast(unsigned int, (b)+MAXARG_sBx))





#define CREATE_ABC(o,a,b,c)	(cast(Instruction, o) \

			| (cast(Instruction, a)<<POS_A) \

			| (cast(Instruction, b)<<POS_B) \

			| (cast(Instruction, c)<<POS_C))



#define CREATE_ABx(o,a,bc)	(cast(Instruction, o) \

			| (cast(Instruction, a)<<POS_A) \

			| (cast(Instruction, bc)<<POS_Bx))









/*

** invalid register that fits in 8 bits

*/

#define NO_REG		MAXARG_A





/*

** R(x) - register

** Kst(x) - constant (in constant table)

** RK(x) == if x < MAXSTACK then R(x) else Kst(x-MAXSTACK)

*/





/*

** grep "ORDER OP" if you change these enums

*/



typedef enum {

/*----------------------------------------------------------------------

name		args	description

------------------------------------------------------------------------*/

OP_MOVE,/*	A B	R(A) := R(B)					*/

OP_LOADK,/*	A Bx	R(A) := Kst(Bx)					*/

OP_LOADBOOL,/*	A B C	R(A) := (Bool)B; if (C) PC++			*/

OP_LOADNIL,/*	A B	R(A) := ... := R(B) := nil			*/

OP_GETUPVAL,/*	A B	R(A) := UpValue[B]				*/



OP_GETGLOBAL,/*	A Bx	R(A) := Gbl[Kst(Bx)]				*/

OP_GETTABLE,/*	A B C	R(A) := R(B)[RK(C)]				*/



OP_SETGLOBAL,/*	A Bx	Gbl[Kst(Bx)] := R(A)				*/

OP_SETUPVAL,/*	A B	UpValue[B] := R(A)				*/

OP_SETTABLE,/*	A B C	R(A)[RK(B)] := RK(C)				*/



OP_NEWTABLE,/*	A B C	R(A) := {} (size = B,C)				*/



OP_SELF,/*	A B C	R(A+1) := R(B); R(A) := R(B)[RK(C)]		*/



OP_ADD,/*	A B C	R(A) := RK(B) + RK(C)				*/

OP_SUB,/*	A B C	R(A) := RK(B) - RK(C)				*/

OP_MUL,/*	A B C	R(A) := RK(B) * RK(C)				*/

OP_DIV,/*	A B C	R(A) := RK(B) / RK(C)				*/

OP_POW,/*	A B C	R(A) := RK(B) ^ RK(C)				*/

OP_UNM,/*	A B	R(A) := -R(B)					*/

OP_NOT,/*	A B	R(A) := not R(B)				*/



OP_CONCAT,/*	A B C	R(A) := R(B).. ... ..R(C)			*/



OP_JMP,/*	sBx	PC += sBx					*/



OP_EQ,/*	A B C	if ((RK(B) == RK(C)) ~= A) then pc++		*/

OP_LT,/*	A B C	if ((RK(B) <  RK(C)) ~= A) then pc++  		*/

OP_LE,/*	A B C	if ((RK(B) <= RK(C)) ~= A) then pc++  		*/



OP_TEST,/*	A B C	if (R(B) <=> C) then R(A) := R(B) else pc++	*/ 



OP_CALL,/*	A B C	R(A), ... ,R(A+C-2) := R(A)(R(A+1), ... ,R(A+B-1)) */

OP_TAILCALL,/*	A B C	return R(A)(R(A+1), ... ,R(A+B-1))		*/

OP_RETURN,/*	A B	return R(A), ... ,R(A+B-2)	(see note)	*/



OP_FORLOOP,/*	A sBx	R(A)+=R(A+2); if R(A) <?= R(A+1) then PC+= sBx	*/



OP_TFORLOOP,/*	A C	R(A+2), ... ,R(A+2+C) := R(A)(R(A+1), R(A+2)); 

                        if R(A+2) ~= nil then pc++			*/

OP_TFORPREP,/*	A sBx	if type(R(A)) == table then R(A+1):=R(A), R(A):=next;

			PC += sBx					*/



OP_SETLIST,/*	A Bx	R(A)[Bx-Bx%FPF+i] := R(A+i), 1 <= i <= Bx%FPF+1	*/

OP_SETLISTO,/*	A Bx							*/



OP_CLOSE,/*	A 	close all variables in the stack up to (>=) R(A)*/

OP_CLOSURE/*	A Bx	R(A) := closure(KPROTO[Bx], R(A), ... ,R(A+n))	*/

} OpCode;





#define NUM_OPCODES	(cast(int, OP_CLOSURE+1))







/*===========================================================================

  Notes:

  (1) In OP_CALL, if (B == 0) then B = top. C is the number of returns - 1,

      and can be 0: OP_CALL then sets `top' to last_result+1, so

      next open instruction (OP_CALL, OP_RETURN, OP_SETLIST) may use `top'.



  (2) In OP_RETURN, if (B == 0) then return up to `top'



  (3) For comparisons, B specifies what conditions the test should accept.



  (4) All `skips' (pc++) assume that next instruction is a jump

===========================================================================*/





/*

** masks for instruction properties

*/  

enum OpModeMask {

  OpModeBreg = 2,       /* B is a register */

  OpModeBrk,		/* B is a register/constant */

  OpModeCrk,           /* C is a register/constant */

  OpModesetA,           /* instruction set register A */

  OpModeK,              /* Bx is a constant */

  OpModeT		/* operator is a test */

  

};





extern const lu_byte luaP_opmodes[NUM_OPCODES];



#define getOpMode(m)            (cast(enum OpMode, luaP_opmodes[m] & 3))

#define testOpMode(m, b)        (luaP_opmodes[m] & (1 << (b)))





#ifdef LUA_OPNAMES

extern const char *const luaP_opnames[];  /* opcode names */

#endif







/* number of list items to accumulate before a SETLIST instruction */

/* (must be a power of 2) */

#define LFIELDS_PER_FLUSH	32





#endif

