src/main/java/org/luaj/vm3/Lua.java

/*******************************************************************************
* Copyright (c) 2009-2011 Luaj.org. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
******************************************************************************/
package org.luaj.vm3;

/**
 * Constants for lua limits and opcodes. 
 * <p>
 * This is a direct translation of C lua distribution header file constants
 * for bytecode creation and processing.  
 */
public class Lua {
	/** version is supplied by ant build task */
	public static final String _VERSION = "Luaj 0.0";

	/** use return values from previous op */
	public static final int LUA_MULTRET = -1;

	// from lopcodes.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.
	===========================================================================*/

	/* basic instruction format */
	public static final int iABC = 0;
	public static final int iABx = 1;
	public static final int iAsBx = 2;
	public static final int iAx = 3;

	/*
	** size and position of opcode arguments.
	*/
	public static final int SIZE_C = 9;
	public static final int SIZE_B = 9;
	public static final int SIZE_Bx = (SIZE_C + SIZE_B);
	public static final int SIZE_A = 8;
	public static final int SIZE_Ax = (SIZE_C + SIZE_B + SIZE_A);

	public static final int SIZE_OP = 6;

	public static final int POS_OP = 0;
	public static final int POS_A = (POS_OP + SIZE_OP);
	public static final int POS_C = (POS_A + SIZE_A);
	public static final int POS_B = (POS_C + SIZE_C);
	public static final int POS_Bx = POS_C;
	public static final int POS_Ax = POS_A;

	public static final int MAX_OP = ((1 << SIZE_OP) - 1);
	public static final int MAXARG_A = ((1 << SIZE_A) - 1);
	public static final int MAXARG_B = ((1 << SIZE_B) - 1);
	public static final int MAXARG_C = ((1 << SIZE_C) - 1);
	public static final int MAXARG_Bx = ((1 << SIZE_Bx) - 1);
	public static final int MAXARG_sBx = (MAXARG_Bx >> 1); /* `sBx' is signed */
	public static final int MAXARG_Ax = ((1 << SIZE_Ax) - 1);

	public static final int MASK_OP = ((1 << SIZE_OP) - 1) << POS_OP;
	public static final int MASK_A = ((1 << SIZE_A) - 1) << POS_A;
	public static final int MASK_B = ((1 << SIZE_B) - 1) << POS_B;
	public static final int MASK_C = ((1 << SIZE_C) - 1) << POS_C;
	public static final int MASK_Bx = ((1 << SIZE_Bx) - 1) << POS_Bx;

	public static final int MASK_NOT_OP = ~MASK_OP;
	public static final int MASK_NOT_A = ~MASK_A;
	public static final int MASK_NOT_B = ~MASK_B;
	public static final int MASK_NOT_C = ~MASK_C;
	public static final int MASK_NOT_Bx = ~MASK_Bx;

	/*
	** the following macros help to manipulate instructions
	*/
	public static int GET_OPCODE(int i) {
		return (i >> POS_OP) & MAX_OP;
	}

	public static int GETARG_A(int i) {
		return (i >> POS_A) & MAXARG_A;
	}

	public static int GETARG_Ax(int i) {
		return (i >> POS_Ax) & MAXARG_Ax;
	}

	public static int GETARG_B(int i) {
		return (i >> POS_B) & MAXARG_B;
	}

	public static int GETARG_C(int i) {
		return (i >> POS_C) & MAXARG_C;
	}

	public static int GETARG_Bx(int i) {
		return (i >> POS_Bx) & MAXARG_Bx;
	}

	public static int GETARG_sBx(int i) {
		return ((i >> POS_Bx) & MAXARG_Bx) - MAXARG_sBx;
	}

	/*
	** Macros to operate RK indices
	*/

	/** this bit 1 means constant (0 means register) */
	public static final int BITRK = (1 << (SIZE_B - 1));

	/** test whether value is a constant */
	public static boolean ISK(int x) {
		return 0 != ((x) & BITRK);
	}

	/** gets the index of the constant */
	public static int INDEXK(int r) {
		return ((int) (r) & ~BITRK);
	}

	public static final int MAXINDEXRK = (BITRK - 1);

	/** code a constant index as a RK value */
	public static int RKASK(int x) {
		return ((x) | BITRK);
	}

	/**
	** invalid register that fits in 8 bits
	*/
	public static final int 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
	*/

	/*----------------------------------------------------------------------
	name		args	description
	------------------------------------------------------------------------*/
	public static final int OP_MOVE = 0; /*	A B	R(A) := R(B)					*/
	public static final int OP_LOADK = 1; /*	A Bx	R(A) := Kst(Bx)					*/
	public static final int OP_LOADKX = 2; /*	A 	R(A) := Kst(extra arg)					*/
	public static final int OP_LOADBOOL = 3; /*	A B C	R(A) := (Bool)B; if (C) pc++			*/
	public static final int OP_LOADNIL = 4; /*	A B	R(A) := ... := R(A+B) := nil			*/
	public static final int OP_GETUPVAL = 5; /*	A B	R(A) := UpValue[B]				*/

	public static final int OP_GETTABUP = 6; /*	A B C	R(A) := UpValue[B][RK(C)]			*/
	public static final int OP_GETTABLE = 7; /*	A B C	R(A) := R(B)[RK(C)]				*/

	public static final int OP_SETTABUP = 8; /*	A B C	UpValue[A][RK(B)] := RK(C)			*/
	public static final int OP_SETUPVAL = 9; /*	A B	UpValue[B] := R(A)				*/
	public static final int OP_SETTABLE = 10; /*	A B C	R(A)[RK(B)] := RK(C)				*/

	public static final int OP_NEWTABLE = 11; /*	A B C	R(A) := {} (size = B,C)				*/

	public static final int OP_SELF = 12; /*	A B C	R(A+1) := R(B); R(A) := R(B)[RK(C)]		*/

	public static final int OP_ADD = 13; /*	A B C	R(A) := RK(B) + RK(C)				*/
	public static final int OP_SUB = 14; /*	A B C	R(A) := RK(B) - RK(C)				*/
	public static final int OP_MUL = 15; /*	A B C	R(A) := RK(B) * RK(C)				*/
	public static final int OP_DIV = 16; /*	A B C	R(A) := RK(B) / RK(C)				*/
	public static final int OP_MOD = 17; /*	A B C	R(A) := RK(B) % RK(C)				*/
	public static final int OP_POW = 18; /*	A B C	R(A) := RK(B) ^ RK(C)				*/
	public static final int OP_UNM = 19; /*	A B	R(A) := -R(B)					*/
	public static final int OP_NOT = 20; /*	A B	R(A) := not R(B)				*/
	public static final int OP_LEN = 21; /*	A B	R(A) := length of R(B)				*/

	public static final int OP_CONCAT = 22; /*	A B C	R(A) := R(B).. ... ..R(C)			*/

	public static final int OP_JMP = 23; /*	sBx	pc+=sBx					*/
	public static final int OP_EQ = 24; /*	A B C	if ((RK(B) == RK(C)) ~= A) then pc++		*/
	public static final int OP_LT = 25; /*	A B C	if ((RK(B) <  RK(C)) ~= A) then pc++  		*/
	public static final int OP_LE = 26; /*	A B C	if ((RK(B) <= RK(C)) ~= A) then pc++  		*/

	public static final int OP_TEST = 27; /*	A C	if not (R(A) <=> C) then pc++			*/
	public static final int OP_TESTSET = 28; /*	A B C	if (R(B) <=> C) then R(A) := R(B) else pc++	*/

	public static final int OP_CALL = 29; /*	A B C	R(A), ... ,R(A+C-2) := R(A)(R(A+1), ... ,R(A+B-1)) */
	public static final int OP_TAILCALL = 30; /*	A B C	return R(A)(R(A+1), ... ,R(A+B-1))		*/
	public static final int OP_RETURN = 31; /*	A B	return R(A), ... ,R(A+B-2)	(see note)	*/

	public static final int OP_FORLOOP = 32; /*	A sBx	R(A)+=R(A+2);
												if R(A) <?= R(A+1) then { pc+=sBx; R(A+3)=R(A) }*/
	public static final int OP_FORPREP = 33; /*	A sBx	R(A)-=R(A+2); pc+=sBx				*/

	public static final int OP_TFORCALL = 34; /* A C	R(A+3), ... ,R(A+2+C) := R(A)(R(A+1), R(A+2));	*/
	public static final int OP_TFORLOOP = 35; /* A sBx   if R(A+1) ~= nil then { R(A)=R(A+1); pc += sBx } */
	public static final int OP_SETLIST = 36; /*	A B C	R(A)[(C-1)*FPF+i] := R(A+i), 1 <= i <= B	*/

	public static final int OP_CLOSURE = 37; /*	A Bx	R(A) := closure(KPROTO[Bx], R(A), ... ,R(A+n))	*/

	public static final int OP_VARARG = 38; /*	A B	R(A), R(A+1), ..., R(A+B-1) = vararg		*/

	public static final int OP_EXTRAARG = 39; /* Ax	extra (larger) argument for previous opcode	*/

	public static final int NUM_OPCODES = OP_EXTRAARG + 1;

	/* pseudo-opcodes used in parsing only.  */
	public static final int OP_GT = 63; // > 
	public static final int OP_GE = 62; // >=
	public static final int OP_NEQ = 61; // ~= 
	public static final int OP_AND = 60; // and 
	public static final int OP_OR = 59; // or 

	/*===========================================================================
	  Notes:
	  (*) 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'.

	  (*) 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 real C

	  (*) 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
	*/

	public static final int OpArgN = 0; /* argument is not used */
	public static final int OpArgU = 1; /* argument is used */
	public static final int OpArgR = 2; /* argument is a register or a jump offset */
	public static final int OpArgK = 3; /* argument is a constant or register/constant */

	public static final int[] luaP_opmodes = {
	/*   T        A           B             C          mode		   opcode	*/
	(0 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgN << 2) | (iABC), /* OP_MOVE */
	(0 << 7) | (1 << 6) | (OpArgK << 4) | (OpArgN << 2) | (iABx), /* OP_LOADK */
	(0 << 7) | (1 << 6) | (OpArgN << 4) | (OpArgN << 2) | (iABx), /* OP_LOADKX */
	(0 << 7) | (1 << 6) | (OpArgU << 4) | (OpArgU << 2) | (iABC), /* OP_LOADBOOL */
	(0 << 7) | (1 << 6) | (OpArgU << 4) | (OpArgN << 2) | (iABC), /* OP_LOADNIL */
	(0 << 7) | (1 << 6) | (OpArgU << 4) | (OpArgN << 2) | (iABC), /* OP_GETUPVAL */
	(0 << 7) | (1 << 6) | (OpArgU << 4) | (OpArgK << 2) | (iABC), /* OP_GETTABUP */
	(0 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgK << 2) | (iABC), /* OP_GETTABLE */
	(0 << 7) | (0 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_SETTABUP */
	(0 << 7) | (0 << 6) | (OpArgU << 4) | (OpArgN << 2) | (iABC), /* OP_SETUPVAL */
	(0 << 7) | (0 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_SETTABLE */
	(0 << 7) | (1 << 6) | (OpArgU << 4) | (OpArgU << 2) | (iABC), /* OP_NEWTABLE */
	(0 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgK << 2) | (iABC), /* OP_SELF */
	(0 << 7) | (1 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_ADD */
	(0 << 7) | (1 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_SUB */
	(0 << 7) | (1 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_MUL */
	(0 << 7) | (1 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_DIV */
	(0 << 7) | (1 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_MOD */
	(0 << 7) | (1 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_POW */
	(0 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgN << 2) | (iABC), /* OP_UNM */
	(0 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgN << 2) | (iABC), /* OP_NOT */
	(0 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgN << 2) | (iABC), /* OP_LEN */
	(0 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgR << 2) | (iABC), /* OP_CONCAT */
	(0 << 7) | (0 << 6) | (OpArgR << 4) | (OpArgN << 2) | (iAsBx), /* OP_JMP */
	(1 << 7) | (0 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_EQ */
	(1 << 7) | (0 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_LT */
	(1 << 7) | (0 << 6) | (OpArgK << 4) | (OpArgK << 2) | (iABC), /* OP_LE */
	(1 << 7) | (0 << 6) | (OpArgN << 4) | (OpArgU << 2) | (iABC), /* OP_TEST */
	(1 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgU << 2) | (iABC), /* OP_TESTSET */
	(0 << 7) | (1 << 6) | (OpArgU << 4) | (OpArgU << 2) | (iABC), /* OP_CALL */
	(0 << 7) | (1 << 6) | (OpArgU << 4) | (OpArgU << 2) | (iABC), /* OP_TAILCALL */
	(0 << 7) | (0 << 6) | (OpArgU << 4) | (OpArgN << 2) | (iABC), /* OP_RETURN */
	(0 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgN << 2) | (iAsBx), /* OP_FORLOOP */
	(0 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgN << 2) | (iAsBx), /* OP_FORPREP */
	(0 << 7) | (0 << 6) | (OpArgN << 4) | (OpArgU << 2) | (iABC), /* OP_TFORCALL */
	(1 << 7) | (1 << 6) | (OpArgR << 4) | (OpArgN << 2) | (iAsBx), /* OP_TFORLOOP */
	(0 << 7) | (0 << 6) | (OpArgU << 4) | (OpArgU << 2) | (iABC), /* OP_SETLIST */
	(0 << 7) | (1 << 6) | (OpArgU << 4) | (OpArgN << 2) | (iABx), /* OP_CLOSURE */
	(0 << 7) | (1 << 6) | (OpArgU << 4) | (OpArgN << 2) | (iABC), /* OP_VARARG */
	(0 << 7) | (0 << 6) | (OpArgU << 4) | (OpArgU << 2) | (iAx), /* OP_EXTRAARG */
	};

	public static int getOpMode(int m) {
		return luaP_opmodes[m] & 3;
	}

	public static int getBMode(int m) {
		return (luaP_opmodes[m] >> 4) & 3;
	}

	public static int getCMode(int m) {
		return (luaP_opmodes[m] >> 2) & 3;
	}

	public static boolean testAMode(int m) {
		return 0 != (luaP_opmodes[m] & (1 << 6));
	}

	public static boolean testTMode(int m) {
		return 0 != (luaP_opmodes[m] & (1 << 7));
	}

	/* number of list items to accumulate before a SETLIST instruction */
	public static final int LFIELDS_PER_FLUSH = 50;

	public static final int MAXSRC = 60;

	public static String chunkid(String source) {
		if (source.startsWith("="))
			return source.substring(1);
		String end = "";
		if (source.startsWith("@")) {
			source = source.substring(1);
		} else {
			source = "[string \"" + source;
			end = "\"]";
		}
		int n = source.length() + end.length();
		if (n > MAXSRC)
			source = source.substring(0, MAXSRC - end.length() - 3) + "...";
		return source + end;
	}
}