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/*
** $Id: lopcodes.h,v 1.125.1.1 2007/12/27 13:02:25 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.
===========================================================================*/
/*
三种指令的格式
iABC B:9 C:9 A:8 Opcode:6
iABx Bx:18 A:8 Opcode:6
iAsBx sBx:18 A:8 Opcode:6
注：sBx是signed BX
寄存器就是相对于callinfo和lua_state的当前调用的base的某个偏移（即ABC值)
*/
enum OpMode {iABC, iABx, iAsBx}; /* basic instruction format */
/*
** size and position of opcode arguments.
*/
//c 单个指令Instruction的每部分的大小
// 9 + 9 + 8 + 6 = 32 bits
#define SIZE_B 9
#define SIZE_C 9
#define SIZE_Bx (SIZE_C + SIZE_B)
#define SIZE_A 8
#define SIZE_OP 6
//c 每个部分在Instruction中的偏移量，从低位到高位
#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
/*
** 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
#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
*/
//c 获取和设置指令中的某个部分
#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_A(i) (cast(int, ((i)>>POS_A) & MASK1(SIZE_A,0)))
#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)<<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))
/*
** Macros to operate RK indices
*/
//c 高位为1时代表常数
/* this bit 1 means constant (0 means register) */
#define BITRK (1 << (SIZE_B - 1))
//c 检查x是不是常量，规定高位是1的话就是常量，去常量表里查，而不是寄存器
/* 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_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_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,/* 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 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_TFORLOOP,/* A C R(A+3), ... ,R(A+2+C) := R(A)(R(A+1), R(A+2));
if R(A+3) ~= nil then R(A+2)=R(A+3) else pc++ */
OP_SETLIST,/* A B C R(A)[(C-1)*FPF+i] := R(A+i), 1 <= i <= B */
//setlist有一个优化，当初始化的数量每超过LFIELDS_PER_FLUSH个时，flush一次，这样能够减少
// 比如初始化时元素个数是3个，那么参数C就是1，只需要flush 1次
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)) */
OP_VARARG/* A B R(A), R(A+1), ..., R(A+B-1) = vararg */
} OpCode;
#define NUM_OPCODES (cast(int, OP_VARARG) + 1)
/*===========================================================================
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
*/
//c 指令的参数格式，在luaP_opmodes用到
enum OpArgMask {
OpArgN, /* argument is not used */ // 未使用（没有座位R()和RK()的参数使用）
OpArgU, /* argument is used */ // 使用的
OpArgR, /* argument is a register or a jump offset */ // 寄存器、跳转偏移
OpArgK /* argument is a constant or register/constant */ // 寄存器、常量
};
//c 限制每个指令的具体格式，用来后续判断，起到分类统一处理指令的作用
//c 即lvm.c 中 RA(i)等宏中的check_exp，不过这个检查是可以跳过的，在llimits.h中定义
LUAI_DATA 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_DATA 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
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