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lua/lvm.c

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/*
** $Id: lvm.c,v 1.225 2002/04/10 12:11:07 roberto Exp roberto $
** Lua virtual machine
** See Copyright Notice in lua.h
*/
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "lua.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"
/* limit for table tag-method chains (to avoid loops) */
#define MAXTAGLOOP 10000
static void luaV_checkGC (lua_State *L, StkId top) {
if (G(L)->nblocks >= G(L)->GCthreshold) {
L->top = top; /* limit for active registers */
luaC_collectgarbage(L);
L->top = L->ci->top; /* restore old top position */
}
}
const TObject *luaV_tonumber (const TObject *obj, TObject *n) {
lua_Number num;
if (ttype(obj) == LUA_TNUMBER) return obj;
if (ttype(obj) == LUA_TSTRING && luaO_str2d(svalue(obj), &num)) {
setnvalue(n, num);
return n;
}
else
return NULL;
}
int luaV_tostring (lua_State *L, TObject *obj) {
if (ttype(obj) != LUA_TNUMBER)
return 0;
else {
char s[32]; /* 16 digits, sign, point and \0 (+ some extra...) */
lua_number2str(s, nvalue(obj));
setsvalue(obj, luaS_new(L, s));
return 1;
}
}
static void traceexec (lua_State *L) {
CallInfo *ci = L->ci;
Proto *p = ci_func(ci)->l.p;
int newline = p->lineinfo[pcRel(*ci->pc, p)];
if (pcRel(*ci->pc, p) == 0) /* tracing may be starting now? */
ci->savedpc = *ci->pc; /* initialize `savedpc' */
/* calls linehook when enters a new line or jumps back (loop) */
if (*ci->pc <= ci->savedpc || newline != p->lineinfo[pcRel(ci->savedpc, p)]) {
luaD_lineHook(L, newline);
ci = L->ci; /* previous call may reallocate `ci' */
}
ci->savedpc = *ci->pc;
}
static void callTMres (lua_State *L, const TObject *f,
const TObject *p1, const TObject *p2, TObject *result ) {
ptrdiff_t res = savestack(L, result);
setobj(L->top, f); /* push function */
setobj(L->top+1, p1); /* 1st argument */
setobj(L->top+2, p2); /* 2nd argument */
luaD_checkstack(L, 3); /* cannot check before (could invalidate p1, p2) */
L->top += 3;
luaD_call(L, L->top - 3, 1);
result = restorestack(L, res); /* previous call may change stack */
setobj(result, --L->top); /* get result */
}
static void callTM (lua_State *L, const TObject *f,
const TObject *p1, const TObject *p2, const TObject *p3) {
setobj(L->top, f); /* push function */
setobj(L->top+1, p1); /* 1st argument */
setobj(L->top+2, p2); /* 2nd argument */
setobj(L->top+3, p3); /* 3th argument */
luaD_checkstack(L, 4); /* cannot check before (could invalidate p1...p3) */
L->top += 4;
luaD_call(L, L->top - 4, 0);
}
/*
** Function to index a table.
** Receives the table at `t' and the key at `key'.
** leaves the result at `res'.
*/
void luaV_gettable (lua_State *L, const TObject *t, TObject *key, StkId res) {
const TObject *tm;
int loop = 0;
init:
if (ttype(t) == LUA_TTABLE) { /* `t' is a table? */
Table *et = hvalue(t)->metatable;
if ((tm = fasttm(L, et, TM_GETTABLE)) == NULL) { /* no gettable TM? */
const TObject *h = luaH_get(hvalue(t), key); /* do a primitive get */
/* result is no nil or there is no `index' tag method? */
if (ttype(h) != LUA_TNIL || /* no nil? */
(tm = fasttm(L, et, TM_INDEX)) == NULL) { /* or no index TM? */
setobj(res, h); /* default get */
return;
}
}
/* else will try the tag method */
} else { /* not a table; try a `gettable' tag method */
if (ttype(tm = luaT_gettmbyobj(L, t, TM_GETTABLE)) == LUA_TNIL) {
luaG_typeerror(L, t, "index");
return; /* to avoid warnings */
}
}
if (ttype(tm) == LUA_TFUNCTION)
callTMres(L, tm, t, key, res);
else {
if (++loop == MAXTAGLOOP) luaD_runerror(L, "loop in gettable");
t = tm;
goto init; /* return luaV_gettable(L, tm, key, res); */
}
}
/*
** Receives table at `t', key at `key' and value at `val'.
*/
void luaV_settable (lua_State *L, const TObject *t, TObject *key, StkId val) {
const TObject *tm;
int loop = 0;
init:
if (ttype(t) == LUA_TTABLE) { /* `t' is a table? */
Table *et = hvalue(t)->metatable;
if ((tm = fasttm(L, et, TM_SETTABLE)) == NULL) { /* no TM? */
luaH_set(L, hvalue(t), key, val); /* do a primitive set */
return;
}
/* else will try the tag method */
} else { /* not a table; try a `settable' tag method */
if (ttype(tm = luaT_gettmbyobj(L, t, TM_SETTABLE)) == LUA_TNIL) {
luaG_typeerror(L, t, "index");
return; /* to avoid warnings */
}
}
if (ttype(tm) == LUA_TFUNCTION)
callTM(L, tm, t, key, val);
else {
if (++loop == MAXTAGLOOP) luaD_runerror(L, "loop in settable");
t = tm;
goto init; /* luaV_settable(L, tm, key, val); */
}
}
static int call_binTM (lua_State *L, const TObject *p1, const TObject *p2,
TObject *res, TMS event) {
const TObject *tm = luaT_gettmbyobj(L, p1, event); /* try first operand */
if (ttype(tm) == LUA_TNIL)
tm = luaT_gettmbyobj(L, p2, event); /* try second operand */
if (ttype(tm) != LUA_TFUNCTION) return 0;
callTMres(L, tm, p1, p2, res);
return 1;
}
static void call_arith (lua_State *L, StkId p1, const TObject *p2,
StkId res, TMS event) {
if (!call_binTM(L, p1, p2, res, event))
luaG_aritherror(L, p1, p2);
}
static int luaV_strlessthan (const TString *ls, const TString *rs) {
const char *l = getstr(ls);
size_t ll = ls->tsv.len;
const char *r = getstr(rs);
size_t lr = rs->tsv.len;
for (;;) {
int temp = strcoll(l, r);
if (temp != 0) return (temp < 0);
else { /* strings are equal up to a `\0' */
size_t len = strlen(l); /* index of first `\0' in both strings */
if (len == lr) /* r is finished? */
return 0; /* l is equal or greater than r */
else if (len == ll) /* l is finished? */
return 1; /* l is smaller than r (because r is not finished) */
/* both strings longer than `len'; go on comparing (after the `\0') */
len++;
l += len; ll -= len; r += len; lr -= len;
}
}
}
int luaV_lessthan (lua_State *L, const TObject *l, const TObject *r) {
if (ttype(l) == LUA_TNUMBER && ttype(r) == LUA_TNUMBER)
return (nvalue(l) < nvalue(r));
else if (ttype(l) == LUA_TSTRING && ttype(r) == LUA_TSTRING)
return luaV_strlessthan(tsvalue(l), tsvalue(r));
else { /* try TM */
if (!call_binTM(L, l, r, L->top, TM_LT))
luaG_ordererror(L, l, r);
return !l_isfalse(L->top);
}
}
void luaV_strconc (lua_State *L, int total, int last) {
do {
StkId top = L->ci->base + last + 1;
int n = 2; /* number of elements handled in this pass (at least 2) */
if (!tostring(L, top-2) || !tostring(L, top-1)) {
if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
luaG_concaterror(L, top-2, top-1);
} else if (tsvalue(top-1)->tsv.len > 0) { /* if len=0, do nothing */
/* at least two string values; get as many as possible */
lu_mem tl = cast(lu_mem, tsvalue(top-1)->tsv.len) +
cast(lu_mem, tsvalue(top-2)->tsv.len);
char *buffer;
int i;
while (n < total && tostring(L, top-n-1)) { /* collect total length */
tl += tsvalue(top-n-1)->tsv.len;
n++;
}
if (tl > MAX_SIZET) luaD_runerror(L, "string size overflow");
buffer = luaO_openspace(L, tl, char);
tl = 0;
for (i=n; i>0; i--) { /* concat all strings */
size_t l = tsvalue(top-i)->tsv.len;
memcpy(buffer+tl, svalue(top-i), l);
tl += l;
}
setsvalue(top-n, luaS_newlstr(L, buffer, tl));
}
total -= n-1; /* got `n' strings to create 1 new */
last -= n-1;
} while (total > 1); /* repeat until only 1 result left */
}
static void powOp (lua_State *L, StkId ra, StkId rb, StkId rc) {
const TObject *b = rb;
const TObject *c = rc;
TObject tempb, tempc;
if (tonumber(b, &tempb) && tonumber(c, &tempc)) {
TObject f, o;
setsvalue(&o, luaS_newliteral(L, "pow"));
luaV_gettable(L, gt(L), &o, &f);
if (ttype(&f) != LUA_TFUNCTION)
luaD_runerror(L, "`pow' (for `^' operator) is not a function");
callTMres(L, &f, b, c, ra);
}
else
call_arith(L, rb, rc, ra, TM_POW);
}
/*
** some macros for common tasks in `luaV_execute'
*/
#define runtime_check(L, c) { if (!(c)) return 0; }
#define RA(i) (base+GETARG_A(i))
#define RB(i) (base+GETARG_B(i))
#define RC(i) (base+GETARG_C(i))
#define RKC(i) ((GETARG_C(i) < MAXSTACK) ? \
base+GETARG_C(i) : \
k+GETARG_C(i)-MAXSTACK)
#define KBc(i) (k+GETARG_Bc(i))
#define Arith(op, optm) { \
const TObject *b = RB(i); const TObject *c = RKC(i); \
TObject tempb, tempc; \
if (tonumber(b, &tempb) && tonumber(c, &tempc)) { \
setnvalue(ra, nvalue(b) op nvalue(c)); \
} else \
call_arith(L, RB(i), RKC(i), ra, optm); \
}
#define dojump(pc, i) ((pc) += (i))
StkId luaV_execute (lua_State *L) {
StkId base;
LClosure *cl;
TObject *k;
const Instruction *pc;
callentry: /* entry point when calling new functions */
L->ci->pc = &pc;
L->ci->pb = &base;
pc = L->ci->savedpc;
retentry: /* entry point when returning to old functions */
base = L->ci->base;
cl = &clvalue(base - 1)->l;
k = cl->p->k;
/* main loop of interpreter */
for (;;) {
const Instruction i = *pc++;
StkId ra;
if (L->linehook)
traceexec(L);
ra = RA(i);
lua_assert(L->top <= L->stack + L->stacksize && L->top >= L->ci->base);
lua_assert(L->top == L->ci->top ||
GET_OPCODE(i) == OP_CALL || GET_OPCODE(i) == OP_TAILCALL ||
GET_OPCODE(i) == OP_RETURN || GET_OPCODE(i) == OP_SETLISTO);
switch (GET_OPCODE(i)) {
case OP_MOVE: {
setobj(ra, RB(i));
break;
}
case OP_LOADK: {
setobj(ra, KBc(i));
break;
}
case OP_LOADBOOL: {
setbvalue(ra, GETARG_B(i));
if (GETARG_C(i)) pc++; /* skip next instruction (if C) */
break;
}
case OP_LOADNIL: {
TObject *rb = RB(i);
do {
setnilvalue(rb--);
} while (rb >= ra);
break;
}
case OP_GETUPVAL: {
int b = GETARG_B(i);
setobj(ra, cl->upvals[b]->v);
break;
}
case OP_GETGLOBAL: {
lua_assert(ttype(KBc(i)) == LUA_TSTRING);
luaV_gettable(L, gt(L), KBc(i), ra);
break;
}
case OP_GETTABLE: {
luaV_gettable(L, RB(i), RKC(i), ra);
break;
}
case OP_SETGLOBAL: {
lua_assert(ttype(KBc(i)) == LUA_TSTRING);
luaV_settable(L, gt(L), KBc(i), ra);
break;
}
case OP_SETUPVAL: {
int b = GETARG_B(i);
setobj(cl->upvals[b]->v, ra);
break;
}
case OP_SETTABLE: {
luaV_settable(L, RB(i), RKC(i), ra);
break;
}
case OP_NEWTABLE: {
int b = GETARG_B(i);
if (b > 0) b = twoto(b-1);
sethvalue(ra, luaH_new(L, b, GETARG_C(i)));
luaV_checkGC(L, ra+1);
break;
}
case OP_SELF: {
StkId rb = RB(i);
setobj(ra+1, rb);
luaV_gettable(L, rb, RKC(i), ra);
break;
}
case OP_ADD: {
Arith( + , TM_ADD);
break;
}
case OP_SUB: {
Arith( - , TM_SUB);
break;
}
case OP_MUL: {
Arith( * , TM_MUL);
break;
}
case OP_DIV: {
Arith( / , TM_DIV);
break;
}
case OP_POW: {
powOp(L, ra, RB(i), RKC(i));
break;
}
case OP_UNM: {
const TObject *rb = RB(i);
if (tonumber(rb, ra)) {
setnvalue(ra, -nvalue(rb));
}
else {
TObject temp;
setnilvalue(&temp);
call_arith(L, RB(i), &temp, ra, TM_UNM);
}
break;
}
case OP_NOT: {
int res = l_isfalse(RB(i)); /* next assignment may change this value */
setbvalue(ra, res);
break;
}
case OP_CONCAT: {
int b = GETARG_B(i);
int c = GETARG_C(i);
luaV_strconc(L, c-b+1, c); /* may change `base' (and `ra') */
setobj(base+GETARG_A(i), base+b);
luaV_checkGC(L, base+c+1);
break;
}
case OP_JMP: {
dojump(pc, GETARG_sBc(i));
break;
}
case OP_TESTEQ: { /* skip next instruction if test fails */
if (!luaO_equalObj(ra, RKC(i))) pc++;
break;
}
case OP_TESTNE: {
if (luaO_equalObj(ra, RKC(i))) pc++;
break;
}
case OP_TESTLT: {
if (!luaV_lessthan(L, ra, RKC(i))) pc++;
break;
}
case OP_TESTLE: { /* b <= c === !(c<b) */
if (luaV_lessthan(L, RKC(i), ra)) pc++;
break;
}
case OP_TESTGT: { /* b > c === (c<b) */
if (!luaV_lessthan(L, RKC(i), ra)) pc++;
break;
}
case OP_TESTGE: { /* b >= c === !(b<c) */
if (luaV_lessthan(L, ra, RKC(i))) pc++;
break;
}
case OP_TESTT: {
StkId rb = RB(i);
if (l_isfalse(rb)) pc++;
else setobj(ra, rb);
break;
}
case OP_TESTF: {
StkId rb = RB(i);
if (!l_isfalse(rb)) pc++;
else setobj(ra, rb);
break;
}
case OP_CALL: {
StkId firstResult;
int b = GETARG_B(i);
int nresults;
if (b != 0) L->top = ra+b; /* else previous instruction set top */
nresults = GETARG_C(i) - 1;
firstResult = luaD_precall(L, ra);
if (firstResult) {
if (firstResult > L->top) { /* yield? */
(L->ci-1)->savedpc = pc;
return NULL;
}
/* it was a C function (`precall' called it); adjust results */
luaD_poscall(L, nresults, firstResult);
if (nresults >= 0) L->top = L->ci->top;
}
else { /* it is a Lua function: `call' it */
(L->ci-1)->savedpc = pc;
goto callentry;
}
break;
}
case OP_TAILCALL: {
int b = GETARG_B(i);
if (L->openupval) luaF_close(L, base);
if (b != 0) L->top = ra+b; /* else previous instruction set top */
luaD_poscall(L, LUA_MULTRET, ra); /* move down function and args. */
ra = luaD_precall(L, base-1);
if (ra == NULL) goto callentry; /* it is a Lua function */
else if (ra > L->top) return NULL; /* yield??? */
else goto ret;
}
case OP_RETURN: {
int b;
if (L->openupval) luaF_close(L, base);
b = GETARG_B(i);
if (b != 0) L->top = ra+b-1;
lua_assert(L->ci->pc == &pc);
}
ret: {
CallInfo *ci;
ci = L->ci - 1;
if (ci->pc != &pc) /* previous function was running `here'? */
return ra; /* no: return */
else { /* yes: continue its execution */
int nresults;
lua_assert(ttype(ci->base-1) == LUA_TFUNCTION);
pc = ci->savedpc;
lua_assert(GET_OPCODE(*(pc-1)) == OP_CALL);
nresults = GETARG_C(*(pc-1)) - 1;
luaD_poscall(L, nresults, ra);
if (nresults >= 0) L->top = L->ci->top;
goto retentry;
}
break;
}
case OP_FORLOOP: {
lua_Number step, index, limit;
int j = GETARG_sBc(i);
const TObject *plimit = ra+1;
const TObject *pstep = ra+2;
if (ttype(ra) != LUA_TNUMBER)
luaD_runerror(L, "`for' initial value must be a number");
if (!tonumber(plimit, ra+1))
luaD_runerror(L, "`for' limit must be a number");
if (!tonumber(pstep, ra+2))
luaD_runerror(L, "`for' step must be a number");
step = nvalue(pstep);
index = nvalue(ra) + step; /* increment index */
limit = nvalue(plimit);
if (step > 0 ? index <= limit : index >= limit) {
dojump(pc, j); /* jump back */
chgnvalue(ra, index); /* update index */
}
break;
}
case OP_TFORLOOP: {
setobj(ra+4, ra+2);
setobj(ra+3, ra+1);
setobj(ra+2, ra);
L->top = ra+5;
luaD_call(L, ra+2, GETARG_C(i) + 1);
L->top = L->ci->top;
if (ttype(ra+2) != LUA_TNIL) pc++; /* skip jump (keep looping) */
break;
}
case OP_TFORPREP: {
if (ttype(ra) == LUA_TTABLE) {
setobj(ra+1, ra);
setsvalue(ra, luaS_new(L, "next"));
luaV_gettable(L, gt(L), ra, ra);
}
break;
}
case OP_SETLIST:
case OP_SETLISTO: {
int bc;
int n;
Table *h;
runtime_check(L, ttype(ra) == LUA_TTABLE);
h = hvalue(ra);
bc = GETARG_Bc(i);
if (GET_OPCODE(i) == OP_SETLIST)
n = (bc&(LFIELDS_PER_FLUSH-1)) + 1;
else {
n = L->top - ra - 1;
L->top = L->ci->top;
}
bc &= ~(LFIELDS_PER_FLUSH-1); /* bc = bc - bc%FPF */
for (; n > 0; n--)
luaH_setnum(L, h, bc+n, ra+n);
break;
}
case OP_CLOSE: {
luaF_close(L, ra);
break;
}
case OP_CLOSURE: {
Proto *p;
Closure *ncl;
int nup, j;
p = cl->p->p[GETARG_Bc(i)];
nup = p->nupvalues;
ncl = luaF_newLclosure(L, nup);
ncl->l.p = p;
for (j=0; j<nup; j++, pc++) {
if (GET_OPCODE(*pc) == OP_GETUPVAL)
ncl->l.upvals[j] = cl->upvals[GETARG_B(*pc)];
else {
lua_assert(GET_OPCODE(*pc) == OP_MOVE);
ncl->l.upvals[j] = luaF_findupval(L, base + GETARG_B(*pc));
}
}
setclvalue(ra, ncl);
luaV_checkGC(L, L->top);
break;
}
}
}
}
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