/*
** $Id: lopcodes.h,v 1.142.1.1 2013/04/12 18:48:47 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
	'Ax' : 26 bits ('A', 'B', and 'C' together)
	`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,
	iAx
}; /* 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_Ax (SIZE_C + SIZE_B + SIZE_A)

#define SIZE_OP 6

#define POS_OP 0
#define POS_A (POS_OP + SIZE_OP)
#define POS_C (POS_A + SIZE_A)
#define POS_B (POS_C + SIZE_C)
#define POS_Bx POS_C
#define POS_Ax POS_A

/*
** limits for opcode arguments.
** we use (signed) int to manipulate most arguments,
** so they must fit in LUAI_BITSINT-1 bits (-1 for sign)
*/
#if SIZE_Bx < LUAI_BITSINT - 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

#if SIZE_Ax < LUAI_BITSINT - 1
#define MAXARG_Ax ((1 << SIZE_Ax) - 1)
#else
#define MAXARG_Ax 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) >> POS_OP) & MASK1(SIZE_OP, 0)))
#define SET_OPCODE(i, o) ((i) = (((i)&MASK0(SIZE_OP, POS_OP)) | \
								 ((cast(Instruction, o) << POS_OP) & MASK1(SIZE_OP, POS_OP))))

#define getarg(i, pos, size) (cast(int, ((i) >> pos) & MASK1(size, 0)))
#define setarg(i, v, pos, size) ((i) = (((i)&MASK0(size, pos)) | \
										((cast(Instruction, v) << pos) & MASK1(size, pos))))

#define GETARG_A(i) getarg(i, POS_A, SIZE_A)
#define SETARG_A(i, v) setarg(i, v, POS_A, SIZE_A)

#define GETARG_B(i) getarg(i, POS_B, SIZE_B)
#define SETARG_B(i, v) setarg(i, v, POS_B, SIZE_B)

#define GETARG_C(i) getarg(i, POS_C, SIZE_C)
#define SETARG_C(i, v) setarg(i, v, POS_C, SIZE_C)

#define GETARG_Bx(i) getarg(i, POS_Bx, SIZE_Bx)
#define SETARG_Bx(i, v) setarg(i, v, POS_Bx, SIZE_Bx)

#define GETARG_Ax(i) getarg(i, POS_Ax, SIZE_Ax)
#define SETARG_Ax(i, v) setarg(i, v, POS_Ax, SIZE_Ax)

#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) << POS_OP) | (cast(Instruction, a) << POS_A) | (cast(Instruction, b) << POS_B) | (cast(Instruction, c) << POS_C))

#define CREATE_ABx(o, a, bc) ((cast(Instruction, o) << POS_OP) | (cast(Instruction, a) << POS_A) | (cast(Instruction, bc) << POS_Bx))

#define CREATE_Ax(o, a) ((cast(Instruction, o) << POS_OP) | (cast(Instruction, a) << POS_Ax))

/*
** Macros to operate RK indices
*/

/* this bit 1 means constant (0 means register) */
#define BITRK (1 << (SIZE_B - 1))

/* test whether value is a constant */
#define ISK(x) ((x)&BITRK)

/* gets the index of the constant */
#define INDEXK(r) ((int)(r) & ~BITRK)

#define MAXINDEXRK (BITRK - 1)

/* code a constant index as a RK value */
#define RKASK(x) ((x) | BITRK)

/*
** invalid register that fits in 8 bits
*/
#define NO_REG MAXARG_A

/*
** R(x) - register
** Kst(x) - constant (in constant table)
** RK(x) == if ISK(x) then Kst(INDEXK(x)) else R(x)
*/

/*
** 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_LOADKX,   /*	A 	R(A) := Kst(extra arg)				*/
	OP_LOADBOOL, /*	A B C	R(A) := (Bool)B; if (C) pc++			*/
	OP_LOADNIL,  /*	A B	R(A), R(A+1), ..., R(A+B) := nil		*/
	OP_GETUPVAL, /*	A B	R(A) := UpValue[B]				*/

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

	OP_SETTABUP, /*	A B C	UpValue[A][RK(B)] := RK(C)			*/
	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_MOD, /*	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_LEN, /*	A B	R(A) := length of R(B)				*/

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

	OP_JMP, /*	A sBx	pc+=sBx; if (A) close all upvalues >= R(A) + 1	*/
	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 C	if not (R(A) <=> C) then pc++			*/
	OP_TESTSET, /*	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; R(A+3)=R(A) }*/
	OP_FORPREP, /*	A sBx	R(A)-=R(A+2); pc+=sBx				*/

	OP_TFORCALL, /*	A C	R(A+3), ... ,R(A+2+C) := R(A)(R(A+1), R(A+2));	*/
	OP_TFORLOOP, /*	A sBx	if R(A+1) ~= nil then { R(A)=R(A+1); pc += sBx }*/

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

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

	OP_VARARG, /*	A B	R(A), R(A+1), ..., R(A+B-2) = vararg		*/

	OP_EXTRAARG /*	Ax	extra (larger) argument for previous opcode	*/
} OpCode;

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

/*===========================================================================
  Notes:
  (*) In OP_CALL, if (B == 0) then B = top. If (C == 0), then `top' is
  set to last_result+1, so next open instruction (OP_CALL, OP_RETURN,
  OP_SETLIST) may use `top'.

  (*) In OP_VARARG, if (B == 0) then use actual number of varargs and
  set top (like in OP_CALL with C == 0).

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

  (*) In OP_SETLIST, if (B == 0) then B = `top'; if (C == 0) then next
  'instruction' is EXTRAARG(real C).

  (*) In OP_LOADKX, the next 'instruction' is always EXTRAARG.

  (*) For comparisons, A specifies what condition the test should accept
  (true or false).

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

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

/*
** masks for instruction properties. The format is:
** bits 0-1: op mode
** bits 2-3: C arg mode
** bits 4-5: B arg mode
** bit 6: instruction set register A
** bit 7: operator is a test (next instruction must be a jump)
*/

enum OpArgMask
{
	OpArgN, /* argument is not used */
	OpArgU, /* argument is used */
	OpArgR, /* argument is a register or a jump offset */
	OpArgK  /* argument is a constant or register/constant */
};

LUAI_DDEC const lu_byte luaP_opmodes[NUM_OPCODES];

#define getOpMode(m) (cast(enum OpMode, luaP_opmodes[m] & 3))
#define getBMode(m) (cast(enum OpArgMask, (luaP_opmodes[m] >> 4) & 3))
#define getCMode(m) (cast(enum OpArgMask, (luaP_opmodes[m] >> 2) & 3))
#define testAMode(m) (luaP_opmodes[m] & (1 << 6))
#define testTMode(m) (luaP_opmodes[m] & (1 << 7))

LUAI_DDEC const char *const luaP_opnames[NUM_OPCODES + 1]; /* opcode names */

/* number of list items to accumulate before a SETLIST instruction */
#define LFIELDS_PER_FLUSH 50

#endif