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lua/lvm.c

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/*
** $Id: lvm.c,v 1.139 2000/10/02 20:10:55 roberto Exp roberto $
** Lua virtual machine
** See Copyright Notice in lua.h
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "lua.h"
#include "lapi.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"
#ifdef OLD_ANSI
#define strcoll(a,b) strcmp(a,b)
#endif
/*
** Extra stack size to run a function:
** TAG_LINE(1), NAME(1), TM calls(3) (plus some extra...)
*/
#define EXTRA_STACK 8
int luaV_tonumber (TObject *obj) {
if (ttype(obj) != TAG_STRING)
return 1;
else {
if (!luaO_str2d(svalue(obj), &nvalue(obj)))
return 2;
ttype(obj) = TAG_NUMBER;
return 0;
}
}
int luaV_tostring (lua_State *L, TObject *obj) { /* LUA_NUMBER */
if (ttype(obj) != TAG_NUMBER)
return 1;
else {
char s[32]; /* 16 digits, sign, point and \0 (+ some extra...) */
lua_number2str(s, nvalue(obj)); /* convert `s' to number */
tsvalue(obj) = luaS_new(L, s);
ttype(obj) = TAG_STRING;
return 0;
}
}
static void traceexec (lua_State *L, StkId base, StkId top, lua_Hook linehook) {
CallInfo *ci = infovalue(base-1);
int *lineinfo = ci->func->f.l->lineinfo;
int pc = (*ci->pc - 1) - ci->func->f.l->code;
int newline;
if (ci->line == 0) { /* first time? */
ci->line = 1;
ci->refi = 0;
ci->lastpc = pc+1; /* make sure it will call linehook */
}
newline = luaG_getline(lineinfo, pc, ci->line, &ci->refi);
/* calls linehook when enters a new line or jumps back (loop) */
if (newline != ci->line || pc <= ci->lastpc) {
ci->line = newline;
L->top = top;
luaD_lineHook(L, base-2, newline, linehook);
}
ci->lastpc = pc;
}
static Closure *luaV_closure (lua_State *L, lua_Tag t, int nelems) {
Closure *c = luaF_newclosure(L, nelems);
L->top -= nelems;
while (nelems--)
c->upvalue[nelems] = *(L->top+nelems);
ttype(L->top) = t;
clvalue(L->top) = c;
incr_top;
return c;
}
void luaV_Cclosure (lua_State *L, lua_CFunction c, int nelems) {
Closure *cl = luaV_closure(L, TAG_CCLOSURE, nelems);
cl->f.c = c;
}
void luaV_Lclosure (lua_State *L, Proto *l, int nelems) {
Closure *cl = luaV_closure(L, TAG_LCLOSURE, nelems);
cl->f.l = l;
}
/*
** Function to index a table.
** Receives the table at `t' and the key at top.
*/
const TObject *luaV_gettable (lua_State *L, StkId t) {
const TObject *im;
int tg;
if (ttype(t) == TAG_TABLE && /* `t' is a table? */
((tg = hvalue(t)->htag) == TAG_TABLE || /* with default tag? */
ttype(luaT_getim(L, tg, IM_GETTABLE)) == TAG_NIL)) { /* or no TM? */
/* do a primitive get */
const TObject *h = luaH_get(L, hvalue(t), L->top-1);
/* result is no nil or there is no `index' tag method? */
if (ttype(h) != TAG_NIL ||
(ttype(im=luaT_getim(L, tg, IM_INDEX)) == TAG_NIL))
return h; /* return result */
/* else call `index' tag method */
}
else { /* try a 'gettable' TM */
im = luaT_getimbyObj(L, t, IM_GETTABLE);
}
if (ttype(im) != TAG_NIL) { /* is there a tag method? */
luaD_checkstack(L, 2);
*(L->top+1) = *(L->top-1); /* key */
*L->top = *t; /* table */
*(L->top-1) = *im; /* tag method */
L->top += 2;
luaD_call(L, L->top - 3, 1);
return L->top - 1; /* call result */
}
else { /* no tag method */
luaG_typeerror(L, t, "index");
return NULL; /* to avoid warnings */
}
}
/*
** Receives table at `t', key at `key' and value at top.
*/
void luaV_settable (lua_State *L, StkId t, StkId key) {
int tg;
if (ttype(t) == TAG_TABLE && /* `t' is a table? */
((tg = hvalue(t)->htag) == TAG_TABLE || /* with default tag? */
ttype(luaT_getim(L, tg, IM_SETTABLE)) == TAG_NIL)) /* or no TM? */
*luaH_set(L, hvalue(t), key) = *(L->top-1); /* do a primitive set */
else { /* try a `settable' tag method */
const TObject *im = luaT_getimbyObj(L, t, IM_SETTABLE);
if (ttype(im) != TAG_NIL) {
luaD_checkstack(L, 3);
*(L->top+2) = *(L->top-1);
*(L->top+1) = *key;
*(L->top) = *t;
*(L->top-1) = *im;
L->top += 3;
luaD_call(L, L->top - 4, 0); /* call `settable' tag method */
}
else /* no tag method... */
luaG_typeerror(L, t, "index");
}
}
const TObject *luaV_getglobal (lua_State *L, TString *s) {
const TObject *value = luaH_getstr(L->gt, s);
TObject *im = luaT_getimbyObj(L, value, IM_GETGLOBAL);
if (ttype(im) == TAG_NIL) /* is there a tag method? */
return value; /* default behavior */
else { /* tag method */
luaD_checkstack(L, 3);
*L->top = *im;
ttype(L->top+1) = TAG_STRING;
tsvalue(L->top+1) = s; /* global name */
*(L->top+2) = *value;
L->top += 3;
luaD_call(L, L->top - 3, 1);
return L->top - 1;
}
}
void luaV_setglobal (lua_State *L, TString *s) {
const TObject *oldvalue = luaH_getstr(L->gt, s);
const TObject *im = luaT_getimbyObj(L, oldvalue, IM_SETGLOBAL);
if (ttype(im) == TAG_NIL) { /* is there a tag method? */
if (oldvalue != &luaO_nilobject) {
/* cast to remove `const' is OK, because `oldvalue' != luaO_nilobject */
*(TObject *)oldvalue = *(L->top - 1);
}
else {
TObject key;
ttype(&key) = TAG_STRING;
tsvalue(&key) = s;
*luaH_set(L, L->gt, &key) = *(L->top - 1);
}
}
else {
luaD_checkstack(L, 3);
*(L->top+2) = *(L->top-1); /* new value */
*(L->top+1) = *oldvalue;
ttype(L->top) = TAG_STRING;
tsvalue(L->top) = s;
*(L->top-1) = *im;
L->top += 3;
luaD_call(L, L->top - 4, 0);
}
}
static int call_binTM (lua_State *L, StkId top, IMS event) {
/* try first operand */
const TObject *im = luaT_getimbyObj(L, top-2, event);
L->top = top;
if (ttype(im) == TAG_NIL) {
im = luaT_getimbyObj(L, top-1, event); /* try second operand */
if (ttype(im) == TAG_NIL) {
im = luaT_getim(L, 0, event); /* try a `global' method */
if (ttype(im) == TAG_NIL)
return 0; /* error */
}
}
lua_pushstring(L, luaT_eventname[event]);
luaD_callTM(L, im, 3, 1);
return 1;
}
static void call_arith (lua_State *L, StkId top, IMS event) {
if (!call_binTM(L, top, event))
luaG_binerror(L, top-2, TAG_NUMBER, "perform arithmetic on");
}
static int luaV_strcomp (const TString *ls, const TString *rs) {
const char *l = ls->str;
size_t ll = ls->u.s.len;
const char *r = rs->str;
size_t lr = rs->u.s.len;
for (;;) {
int temp = strcoll(l, r);
if (temp != 0) return temp;
else { /* strings are equal up to a '\0' */
size_t len = strlen(l); /* index of first '\0' in both strings */
if (len == ll) /* l is finished? */
return (len == lr) ? 0 : -1; /* l is equal or smaller than r */
else if (len == lr) /* r is finished? */
return 1; /* l is greater than r (because l 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, StkId top) {
if (ttype(l) == TAG_NUMBER && ttype(r) == TAG_NUMBER)
return (nvalue(l) < nvalue(r));
else if (ttype(l) == TAG_STRING && ttype(r) == TAG_STRING)
return (luaV_strcomp(tsvalue(l), tsvalue(r)) < 0);
else { /* call TM */
luaD_checkstack(L, 2);
*top++ = *l;
*top++ = *r;
if (!call_binTM(L, top, IM_LT))
luaG_ordererror(L, top-2);
L->top--;
return (ttype(L->top) != TAG_NIL);
}
}
void luaV_strconc (lua_State *L, int total, StkId top) {
do {
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, IM_CONCAT))
luaG_binerror(L, top-2, TAG_STRING, "concat");
}
else if (tsvalue(top-1)->u.s.len > 0) { /* if len=0, do nothing */
/* at least two string values; get as many as possible */
lint32 tl = (lint32)tsvalue(top-1)->u.s.len +
(lint32)tsvalue(top-2)->u.s.len;
char *buffer;
int i;
while (n < total && !tostring(L, top-n-1)) { /* collect total length */
tl += tsvalue(top-n-1)->u.s.len;
n++;
}
if (tl > MAX_SIZET) lua_error(L, "string size overflow");
buffer = luaO_openspace(L, tl);
tl = 0;
for (i=n; i>0; i--) { /* concat all strings */
size_t l = tsvalue(top-i)->u.s.len;
memcpy(buffer+tl, tsvalue(top-i)->str, l);
tl += l;
}
tsvalue(top-n) = luaS_newlstr(L, buffer, tl);
}
total -= n-1; /* got `n' strings to create 1 new */
top -= n-1;
} while (total > 1); /* repeat until only 1 result left */
}
static void luaV_pack (lua_State *L, StkId firstelem) {
int i;
Hash *htab = luaH_new(L, 0);
for (i=0; firstelem+i<L->top; i++)
*luaH_setint(L, htab, i+1) = *(firstelem+i);
/* store counter in field `n' */
luaH_setstrnum(L, htab, luaS_new(L, "n"), i);
L->top = firstelem; /* remove elements from the stack */
ttype(L->top) = TAG_TABLE;
hvalue(L->top) = htab;
incr_top;
}
static void adjust_varargs (lua_State *L, StkId base, int nfixargs) {
int nvararg = (L->top-base) - nfixargs;
if (nvararg < 0)
luaD_adjusttop(L, base, nfixargs);
luaV_pack(L, base+nfixargs);
}
#define dojump(pc, i) { int d = GETARG_S(i); pc += d; }
/*
** Executes the given Lua function. Parameters are between [base,top).
** Returns n such that the the results are between [n,top).
*/
StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
const Proto *tf = cl->f.l;
StkId top; /* keep top local, for performance */
const Instruction *pc = tf->code;
TString **kstr = tf->kstr;
lua_Hook linehook = L->linehook;
infovalue(base-1)->pc = &pc;
luaD_checkstack(L, tf->maxstacksize+EXTRA_STACK);
if (tf->is_vararg) /* varargs? */
adjust_varargs(L, base, tf->numparams);
else
luaD_adjusttop(L, base, tf->numparams);
top = L->top;
/* main loop of interpreter */
for (;;) {
const Instruction i = *pc++;
if (linehook)
traceexec(L, base, top, linehook);
switch (GET_OPCODE(i)) {
case OP_END: {
return L->top; /* no results */
}
case OP_RETURN: {
L->top = top;
return base+GETARG_U(i);
}
case OP_CALL: {
int nres = GETARG_B(i);
if (nres == MULT_RET) nres = LUA_MULTRET;
L->top = top;
luaD_call(L, base+GETARG_A(i), nres);
top = L->top;
break;
}
case OP_TAILCALL: {
L->top = top;
luaD_call(L, base+GETARG_A(i), LUA_MULTRET);
return base+GETARG_B(i);
}
case OP_PUSHNIL: {
int n = GETARG_U(i);
LUA_ASSERT(n>0, "invalid argument");
do {
ttype(top++) = TAG_NIL;
} while (--n > 0);
break;
}
case OP_POP: {
top -= GETARG_U(i);
break;
}
case OP_PUSHINT: {
ttype(top) = TAG_NUMBER;
nvalue(top) = (Number)GETARG_S(i);
top++;
break;
}
case OP_PUSHSTRING: {
ttype(top) = TAG_STRING;
tsvalue(top) = kstr[GETARG_U(i)];
top++;
break;
}
case OP_PUSHNUM: {
ttype(top) = TAG_NUMBER;
nvalue(top) = tf->knum[GETARG_U(i)];
top++;
break;
}
case OP_PUSHNEGNUM: {
ttype(top) = TAG_NUMBER;
nvalue(top) = -tf->knum[GETARG_U(i)];
top++;
break;
}
case OP_PUSHUPVALUE: {
*top++ = cl->upvalue[GETARG_U(i)];
break;
}
case OP_GETLOCAL: {
*top++ = *(base+GETARG_U(i));
break;
}
case OP_GETGLOBAL: {
L->top = top;
*top = *luaV_getglobal(L, kstr[GETARG_U(i)]);
top++;
break;
}
case OP_GETTABLE: {
L->top = top;
top--;
*(top-1) = *luaV_gettable(L, top-1);
break;
}
case OP_GETDOTTED: {
ttype(top) = TAG_STRING;
tsvalue(top) = kstr[GETARG_U(i)];
L->top = top+1;
*(top-1) = *luaV_gettable(L, top-1);
break;
}
case OP_GETINDEXED: {
*top = *(base+GETARG_U(i));
L->top = top+1;
*(top-1) = *luaV_gettable(L, top-1);
break;
}
case OP_PUSHSELF: {
TObject receiver;
receiver = *(top-1);
ttype(top) = TAG_STRING;
tsvalue(top++) = kstr[GETARG_U(i)];
L->top = top;
*(top-2) = *luaV_gettable(L, top-2);
*(top-1) = receiver;
break;
}
case OP_CREATETABLE: {
L->top = top;
luaC_checkGC(L);
hvalue(top) = luaH_new(L, GETARG_U(i));
ttype(top) = TAG_TABLE;
top++;
break;
}
case OP_SETLOCAL: {
*(base+GETARG_U(i)) = *(--top);
break;
}
case OP_SETGLOBAL: {
L->top = top;
luaV_setglobal(L, kstr[GETARG_U(i)]);
top--;
break;
}
case OP_SETTABLE: {
StkId t = top-GETARG_A(i);
L->top = top;
luaV_settable(L, t, t+1);
top -= GETARG_B(i); /* pop values */
break;
}
case OP_SETLIST: {
int aux = GETARG_A(i) * LFIELDS_PER_FLUSH;
int n = GETARG_B(i);
Hash *arr = hvalue(top-n-1);
L->top = top-n; /* final value of `top' (in case of errors) */
for (; n; n--)
*luaH_setint(L, arr, n+aux) = *(--top);
break;
}
case OP_SETMAP: {
int n = GETARG_U(i);
StkId finaltop = top-2*n;
Hash *arr = hvalue(finaltop-1);
L->top = finaltop; /* final value of `top' (in case of errors) */
for (; n; n--) {
top-=2;
*luaH_set(L, arr, top) = *(top+1);
}
break;
}
case OP_ADD: {
if (tonumber(top-2) || tonumber(top-1))
call_arith(L, top, IM_ADD);
else
nvalue(top-2) += nvalue(top-1);
top--;
break;
}
case OP_ADDI: {
if (tonumber(top-1)) {
ttype(top) = TAG_NUMBER;
nvalue(top) = (Number)GETARG_S(i);
call_arith(L, top+1, IM_ADD);
}
else
nvalue(top-1) += (Number)GETARG_S(i);
break;
}
case OP_SUB: {
if (tonumber(top-2) || tonumber(top-1))
call_arith(L, top, IM_SUB);
else
nvalue(top-2) -= nvalue(top-1);
top--;
break;
}
case OP_MULT: {
if (tonumber(top-2) || tonumber(top-1))
call_arith(L, top, IM_MUL);
else
nvalue(top-2) *= nvalue(top-1);
top--;
break;
}
case OP_DIV: {
if (tonumber(top-2) || tonumber(top-1))
call_arith(L, top, IM_DIV);
else
nvalue(top-2) /= nvalue(top-1);
top--;
break;
}
case OP_POW: {
if (!call_binTM(L, top, IM_POW))
lua_error(L, "undefined operation");
top--;
break;
}
case OP_CONCAT: {
int n = GETARG_U(i);
luaV_strconc(L, n, top);
top -= n-1;
L->top = top;
luaC_checkGC(L);
break;
}
case OP_MINUS: {
if (tonumber(top-1)) {
ttype(top) = TAG_NIL;
call_arith(L, top+1, IM_UNM);
}
else
nvalue(top-1) = -nvalue(top-1);
break;
}
case OP_NOT: {
ttype(top-1) =
(ttype(top-1) == TAG_NIL) ? TAG_NUMBER : TAG_NIL;
nvalue(top-1) = 1;
break;
}
case OP_JMPNE: {
top -= 2;
if (!luaO_equalObj(top, top+1)) dojump(pc, i);
break;
}
case OP_JMPEQ: {
top -= 2;
if (luaO_equalObj(top, top+1)) dojump(pc, i);
break;
}
case OP_JMPLT: {
top -= 2;
if (luaV_lessthan(L, top, top+1, top+2)) dojump(pc, i);
break;
}
case OP_JMPLE: { /* a <= b === !(b<a) */
top -= 2;
if (!luaV_lessthan(L, top+1, top, top+2)) dojump(pc, i);
break;
}
case OP_JMPGT: { /* a > b === (b<a) */
top -= 2;
if (luaV_lessthan(L, top+1, top, top+2)) dojump(pc, i);
break;
}
case OP_JMPGE: { /* a >= b === !(a<b) */
top -= 2;
if (!luaV_lessthan(L, top, top+1, top+2)) dojump(pc, i);
break;
}
case OP_JMPT: {
if (ttype(--top) != TAG_NIL) dojump(pc, i);
break;
}
case OP_JMPF: {
if (ttype(--top) == TAG_NIL) dojump(pc, i);
break;
}
case OP_JMPONT: {
if (ttype(top-1) == TAG_NIL) top--;
else dojump(pc, i);
break;
}
case OP_JMPONF: {
if (ttype(top-1) != TAG_NIL) top--;
else dojump(pc, i);
break;
}
case OP_JMP: {
dojump(pc, i);
break;
}
case OP_PUSHNILJMP: {
ttype(top++) = TAG_NIL;
pc++;
break;
}
case OP_FORPREP: {
if (tonumber(top-1))
lua_error(L, "`for' step must be a number");
if (tonumber(top-2))
lua_error(L, "`for' limit must be a number");
if (tonumber(top-3))
lua_error(L, "`for' initial value must be a number");
if (nvalue(top-1) > 0 ?
nvalue(top-3) > nvalue(top-2) :
nvalue(top-3) < nvalue(top-2)) { /* `empty' loop? */
top -= 3; /* remove control variables */
dojump(pc, i); /* jump to loop end */
}
break;
}
case OP_FORLOOP: {
LUA_ASSERT(ttype(top-1) == TAG_NUMBER, "invalid step");
LUA_ASSERT(ttype(top-2) == TAG_NUMBER, "invalid limit");
if (ttype(top-3) != TAG_NUMBER)
lua_error(L, "`for' index must be a number");
nvalue(top-3) += nvalue(top-1); /* increment index */
if (nvalue(top-1) > 0 ?
nvalue(top-3) > nvalue(top-2) :
nvalue(top-3) < nvalue(top-2))
top -= 3; /* end loop: remove control variables */
else
dojump(pc, i); /* repeat loop */
break;
}
case OP_LFORPREP: {
Node *node;
if (ttype(top-1) != TAG_TABLE)
lua_error(L, "`for' table must be a table");
node = luaH_next(L, hvalue(top-1), &luaO_nilobject);
if (node == NULL) { /* `empty' loop? */
top--; /* remove table */
dojump(pc, i); /* jump to loop end */
}
else {
top += 2; /* index,value */
*(top-2) = *key(node);
*(top-1) = *val(node);
}
break;
}
case OP_LFORLOOP: {
Node *node;
LUA_ASSERT(ttype(top-3) == TAG_TABLE, "invalid table");
node = luaH_next(L, hvalue(top-3), top-2);
if (node == NULL) /* end loop? */
top -= 3; /* remove table, key, and value */
else {
*(top-2) = *key(node);
*(top-1) = *val(node);
dojump(pc, i); /* repeat loop */
}
break;
}
case OP_CLOSURE: {
L->top = top;
luaV_Lclosure(L, tf->kproto[GETARG_A(i)], GETARG_B(i));
top = L->top;
luaC_checkGC(L);
break;
}
}
}
}
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