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lopcodes.h
1 /*
2 ** $Id$
3 ** Opcodes for Lua virtual machine
4 ** See Copyright Notice in lua.h
5 */
6 
7 #ifndef lopcodes_h
8 #define lopcodes_h
9 
10 #include "llimits.h"
11 
12 
13 /*===========================================================================
14  We assume that instructions are unsigned numbers.
15  All instructions have an opcode in the first 6 bits.
16  Instructions can have the following fields:
17  `A' : 8 bits
18  `B' : 9 bits
19  `C' : 9 bits
20  `Bx' : 18 bits (`B' and `C' together)
21  `sBx' : signed Bx
22 
23  A signed argument is represented in excess K; that is, the number
24  value is the unsigned value minus K. K is exactly the maximum value
25  for that argument (so that -max is represented by 0, and +max is
26  represented by 2*max), which is half the maximum for the corresponding
27  unsigned argument.
28 ===========================================================================*/
29 
30 
31 enum OpMode {iABC, iABx, iAsBx}; /* basic instruction format */
32 
33 
34 /*
35 ** size and position of opcode arguments.
36 */
37 #define SIZE_C 9
38 #define SIZE_B 9
39 #define SIZE_Bx (SIZE_C + SIZE_B)
40 #define SIZE_A 8
41 
42 #define SIZE_OP 6
43 
44 #define POS_OP 0
45 #define POS_A (POS_OP + SIZE_OP)
46 #define POS_C (POS_A + SIZE_A)
47 #define POS_B (POS_C + SIZE_C)
48 #define POS_Bx POS_C
49 
50 
51 /*
52 ** limits for opcode arguments.
53 ** we use (signed) int to manipulate most arguments,
54 ** so they must fit in LUAI_BITSINT-1 bits (-1 for sign)
55 */
56 #if SIZE_Bx < LUAI_BITSINT-1
57 #define MAXARG_Bx ((1<<SIZE_Bx)-1)
58 #define MAXARG_sBx (MAXARG_Bx>>1) /* `sBx' is signed */
59 #else
60 #define MAXARG_Bx MAX_INT
61 #define MAXARG_sBx MAX_INT
62 #endif
63 
64 
65 #define MAXARG_A ((1<<SIZE_A)-1)
66 #define MAXARG_B ((1<<SIZE_B)-1)
67 #define MAXARG_C ((1<<SIZE_C)-1)
68 
69 
70 /* creates a mask with `n' 1 bits at position `p' */
71 #define MASK1(n,p) ((~((~(Instruction)0)<<n))<<p)
72 
73 /* creates a mask with `n' 0 bits at position `p' */
74 #define MASK0(n,p) (~MASK1(n,p))
75 
76 /*
77 ** the following macros help to manipulate instructions
78 */
79 
80 #define GET_OPCODE(i) (cast(OpCode, ((i)>>POS_OP) & MASK1(SIZE_OP,0)))
81 #define SET_OPCODE(i,o) ((i) = (((i)&MASK0(SIZE_OP,POS_OP)) | \
82  ((cast(Instruction, o)<<POS_OP)&MASK1(SIZE_OP,POS_OP))))
83 
84 #define GETARG_A(i) (cast(int, ((i)>>POS_A) & MASK1(SIZE_A,0)))
85 #define SETARG_A(i,u) ((i) = (((i)&MASK0(SIZE_A,POS_A)) | \
86  ((cast(Instruction, u)<<POS_A)&MASK1(SIZE_A,POS_A))))
87 
88 #define GETARG_B(i) (cast(int, ((i)>>POS_B) & MASK1(SIZE_B,0)))
89 #define SETARG_B(i,b) ((i) = (((i)&MASK0(SIZE_B,POS_B)) | \
90  ((cast(Instruction, b)<<POS_B)&MASK1(SIZE_B,POS_B))))
91 
92 #define GETARG_C(i) (cast(int, ((i)>>POS_C) & MASK1(SIZE_C,0)))
93 #define SETARG_C(i,b) ((i) = (((i)&MASK0(SIZE_C,POS_C)) | \
94  ((cast(Instruction, b)<<POS_C)&MASK1(SIZE_C,POS_C))))
95 
96 #define GETARG_Bx(i) (cast(int, ((i)>>POS_Bx) & MASK1(SIZE_Bx,0)))
97 #define SETARG_Bx(i,b) ((i) = (((i)&MASK0(SIZE_Bx,POS_Bx)) | \
98  ((cast(Instruction, b)<<POS_Bx)&MASK1(SIZE_Bx,POS_Bx))))
99 
100 #define GETARG_sBx(i) (GETARG_Bx(i)-MAXARG_sBx)
101 #define SETARG_sBx(i,b) SETARG_Bx((i),cast(unsigned int, (b)+MAXARG_sBx))
102 
103 
104 #define CREATE_ABC(o,a,b,c) ((cast(Instruction, o)<<POS_OP) \
105  | (cast(Instruction, a)<<POS_A) \
106  | (cast(Instruction, b)<<POS_B) \
107  | (cast(Instruction, c)<<POS_C))
108 
109 #define CREATE_ABx(o,a,bc) ((cast(Instruction, o)<<POS_OP) \
110  | (cast(Instruction, a)<<POS_A) \
111  | (cast(Instruction, bc)<<POS_Bx))
112 
113 
114 /*
115 ** Macros to operate RK indices
116 */
117 
118 /* this bit 1 means constant (0 means register) */
119 #define BITRK (1 << (SIZE_B - 1))
120 
121 /* test whether value is a constant */
122 #define ISK(x) ((x) & BITRK)
123 
124 /* gets the index of the constant */
125 #define INDEXK(r) ((int)(r) & ~BITRK)
126 
127 #define MAXINDEXRK (BITRK - 1)
128 
129 /* code a constant index as a RK value */
130 #define RKASK(x) ((x) | BITRK)
131 
132 
133 /*
134 ** invalid register that fits in 8 bits
135 */
136 #define NO_REG MAXARG_A
137 
138 
139 /*
140 ** R(x) - register
141 ** Kst(x) - constant (in constant table)
142 ** RK(x) == if ISK(x) then Kst(INDEXK(x)) else R(x)
143 */
144 
145 
146 /*
147 ** grep "ORDER OP" if you change these enums
148 */
149 
150 typedef enum {
151 /*----------------------------------------------------------------------
152 name args description
153 ------------------------------------------------------------------------*/
154 OP_MOVE,/* A B R(A) := R(B) */
155 OP_LOADK,/* A Bx R(A) := Kst(Bx) */
156 OP_LOADBOOL,/* A B C R(A) := (Bool)B; if (C) pc++ */
157 OP_LOADNIL,/* A B R(A) := ... := R(B) := nil */
158 OP_GETUPVAL,/* A B R(A) := UpValue[B] */
159 
160 OP_GETGLOBAL,/* A Bx R(A) := Gbl[Kst(Bx)] */
161 OP_GETTABLE,/* A B C R(A) := R(B)[RK(C)] */
162 
163 OP_SETGLOBAL,/* A Bx Gbl[Kst(Bx)] := R(A) */
164 OP_SETUPVAL,/* A B UpValue[B] := R(A) */
165 OP_SETTABLE,/* A B C R(A)[RK(B)] := RK(C) */
166 
167 OP_NEWTABLE,/* A B C R(A) := {} (size = B,C) */
168 
169 OP_SELF,/* A B C R(A+1) := R(B); R(A) := R(B)[RK(C)] */
170 
171 OP_ADD,/* A B C R(A) := RK(B) + RK(C) */
172 OP_SUB,/* A B C R(A) := RK(B) - RK(C) */
173 OP_MUL,/* A B C R(A) := RK(B) * RK(C) */
174 OP_DIV,/* A B C R(A) := RK(B) / RK(C) */
175 OP_MOD,/* A B C R(A) := RK(B) % RK(C) */
176 OP_POW,/* A B C R(A) := RK(B) ^ RK(C) */
177 OP_UNM,/* A B R(A) := -R(B) */
178 OP_NOT,/* A B R(A) := not R(B) */
179 OP_LEN,/* A B R(A) := length of R(B) */
180 
181 OP_CONCAT,/* A B C R(A) := R(B).. ... ..R(C) */
182 
183 OP_JMP,/* sBx pc+=sBx */
184 
185 OP_EQ,/* A B C if ((RK(B) == RK(C)) ~= A) then pc++ */
186 OP_LT,/* A B C if ((RK(B) < RK(C)) ~= A) then pc++ */
187 OP_LE,/* A B C if ((RK(B) <= RK(C)) ~= A) then pc++ */
188 
189 OP_TEST,/* A C if not (R(A) <=> C) then pc++ */
190 OP_TESTSET,/* A B C if (R(B) <=> C) then R(A) := R(B) else pc++ */
191 
192 OP_CALL,/* A B C R(A), ... ,R(A+C-2) := R(A)(R(A+1), ... ,R(A+B-1)) */
193 OP_TAILCALL,/* A B C return R(A)(R(A+1), ... ,R(A+B-1)) */
194 OP_RETURN,/* A B return R(A), ... ,R(A+B-2) (see note) */
195 
196 OP_FORLOOP,/* A sBx R(A)+=R(A+2);
197  if R(A) <?= R(A+1) then { pc+=sBx; R(A+3)=R(A) }*/
198 OP_FORPREP,/* A sBx R(A)-=R(A+2); pc+=sBx */
199 
200 OP_TFORLOOP,/* A C R(A+3), ... ,R(A+2+C) := R(A)(R(A+1), R(A+2));
201  if R(A+3) ~= nil then R(A+2)=R(A+3) else pc++ */
202 OP_SETLIST,/* A B C R(A)[(C-1)*FPF+i] := R(A+i), 1 <= i <= B */
203 
204 OP_CLOSE,/* A close all variables in the stack up to (>=) R(A)*/
205 OP_CLOSURE,/* A Bx R(A) := closure(KPROTO[Bx], R(A), ... ,R(A+n)) */
206 
207 OP_VARARG/* A B R(A), R(A+1), ..., R(A+B-1) = vararg */
208 } OpCode;
209 
210 
211 #define NUM_OPCODES (cast(int, OP_VARARG) + 1)
212 
213 
214 
215 /*===========================================================================
216  Notes:
217  (*) In OP_CALL, if (B == 0) then B = top. C is the number of returns - 1,
218  and can be 0: OP_CALL then sets `top' to last_result+1, so
219  next open instruction (OP_CALL, OP_RETURN, OP_SETLIST) may use `top'.
220 
221  (*) In OP_VARARG, if (B == 0) then use actual number of varargs and
222  set top (like in OP_CALL with C == 0).
223 
224  (*) In OP_RETURN, if (B == 0) then return up to `top'
225 
226  (*) In OP_SETLIST, if (B == 0) then B = `top';
227  if (C == 0) then next `instruction' is real C
228 
229  (*) For comparisons, A specifies what condition the test should accept
230  (true or false).
231 
232  (*) All `skips' (pc++) assume that next instruction is a jump
233 ===========================================================================*/
234 
235 
236 /*
237 ** masks for instruction properties. The format is:
238 ** bits 0-1: op mode
239 ** bits 2-3: C arg mode
240 ** bits 4-5: B arg mode
241 ** bit 6: instruction set register A
242 ** bit 7: operator is a test
243 */
244 
245 enum OpArgMask {
246  OpArgN, /* argument is not used */
247  OpArgU, /* argument is used */
248  OpArgR, /* argument is a register or a jump offset */
249  OpArgK /* argument is a constant or register/constant */
250 };
251 
252 LUAI_DATA const lu_byte luaP_opmodes[NUM_OPCODES];
253 
254 #define getOpMode(m) (cast(enum OpMode, luaP_opmodes[m] & 3))
255 #define getBMode(m) (cast(enum OpArgMask, (luaP_opmodes[m] >> 4) & 3))
256 #define getCMode(m) (cast(enum OpArgMask, (luaP_opmodes[m] >> 2) & 3))
257 #define testAMode(m) (luaP_opmodes[m] & (1 << 6))
258 #define testTMode(m) (luaP_opmodes[m] & (1 << 7))
259 
260 
261 LUAI_DATA const char *const luaP_opnames[NUM_OPCODES+1]; /* opcode names */
262 
263 
264 /* number of list items to accumulate before a SETLIST instruction */
265 #define LFIELDS_PER_FLUSH 50
266 
267 
268 #endif