/*

** $Id: lvm.c,v 2.63.1.3 2007/12/28 15:32:23 roberto Exp $

** Lua virtual machine

** See Copyright Notice in lua.h

*/

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#define lvm_c

#define LUA_CORE

#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  100

const TValue *luaV_tonumber (const TValue *obj, TValue *n) {

  lua_Number num;

  if (ttisnumber(obj)) return obj;

  if (ttisstring(obj) && luaO_str2d(svalue(obj), &num)) {

    setnvalue(n, num);

    return n;

  }

  else

    return NULL;

}

int luaV_tostring (lua_State *L, StkId obj) {

  if (!ttisnumber(obj))

    return 0;

  else {

    char s[LUAI_MAXNUMBER2STR];

    lua_Number n = nvalue(obj);

    lua_number2str(s, n);

    setsvalue2s(L, obj, luaS_new(L, s));

    return 1;

  }

}

static void traceexec (lua_State *L, const Instruction *pc) {

  lu_byte mask = L->hookmask;

  const Instruction *oldpc = L->savedpc;

  L->savedpc = pc;

  if ((mask & LUA_MASKCOUNT) && L->hookcount == 0) {

    resethookcount(L);

    luaD_callhook(L, LUA_HOOKCOUNT, -1);

  }

  if (mask & LUA_MASKLINE) {

    Proto *p = ci_func(L->ci)->l.p;

    int npc = pcRel(pc, p);

    int newline = getline(p, npc);

    /* call linehook when enter a new function, when jump back (loop),

       or when enter a new line */

    if (npc == 0 || pc <= oldpc || newline != getline(p, pcRel(oldpc, p)))

      luaD_callhook(L, LUA_HOOKLINE, newline);

  }

}

static void callTMres (lua_State *L, StkId res, const TValue *f,

                        const TValue *p1, const TValue *p2) {

  ptrdiff_t result = savestack(L, res);

  setobj2s(L, L->top, f);  /* push function */

  setobj2s(L, L->top+1, p1);  /* 1st argument */

  setobj2s(L, L->top+2, p2);  /* 2nd argument */

  luaD_checkstack(L, 3);

  L->top += 3;

  luaD_call(L, L->top - 3, 1);

  res = restorestack(L, result);

  L->top--;

  setobjs2s(L, res, L->top);

}

static void callTM (lua_State *L, const TValue *f, const TValue *p1,

                    const TValue *p2, const TValue *p3) {

  setobj2s(L, L->top, f);  /* push function */

  setobj2s(L, L->top+1, p1);  /* 1st argument */

  setobj2s(L, L->top+2, p2);  /* 2nd argument */

  setobj2s(L, L->top+3, p3);  /* 3th argument */

  luaD_checkstack(L, 4);

  L->top += 4;

  luaD_call(L, L->top - 4, 0);

}

void luaV_gettable (lua_State *L, const TValue *t, TValue *key, StkId val) {

  int loop;

  for (loop = 0; loop < MAXTAGLOOP; loop++) {

    const TValue *tm;

    if (ttistable(t)) {  /* `t' is a table? */

      Table *h = hvalue(t);

      const TValue *res = luaH_get(h, key); /* do a primitive get */

      if (!ttisnil(res) ||  /* result is no nil? */

          (tm = fasttm(L, h->metatable, TM_INDEX)) == NULL) { /* or no TM? */

        setobj2s(L, val, res);

        return;

      }

      /* else will try the tag method */

    }

    else if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_INDEX)))

      luaG_typeerror(L, t, "index");

    if (ttisfunction(tm)) {

      callTMres(L, val, tm, t, key);

      return;

    }

    t = tm;  /* else repeat with `tm' */

  }

  luaG_runerror(L, "loop in gettable");

}

void luaV_settable (lua_State *L, const TValue *t, TValue *key, StkId val) {

  int loop;

  for (loop = 0; loop < MAXTAGLOOP; loop++) {

    const TValue *tm;

    if (ttistable(t)) {  /* `t' is a table? */

      Table *h = hvalue(t);

      TValue *oldval = luaH_set(L, h, key); /* do a primitive set */

      if (!ttisnil(oldval) ||  /* result is no nil? */

          (tm = fasttm(L, h->metatable, TM_NEWINDEX)) == NULL) { /* or no TM? */

        setobj2t(L, oldval, val);

        luaC_barriert(L, h, val);

        return;

      }

      /* else will try the tag method */

    }

    else if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))

      luaG_typeerror(L, t, "index");

    if (ttisfunction(tm)) {

      callTM(L, tm, t, key, val);

      return;

    }

    t = tm;  /* else repeat with `tm' */

  }

  luaG_runerror(L, "loop in settable");

}

static int call_binTM (lua_State *L, const TValue *p1, const TValue *p2,

                       StkId res, TMS event) {

  const TValue *tm = luaT_gettmbyobj(L, p1, event);  /* try first operand */

  if (ttisnil(tm))

    tm = luaT_gettmbyobj(L, p2, event);  /* try second operand */

  if (ttisnil(tm)) return 0;

  callTMres(L, res, tm, p1, p2);

  return 1;

}

static const TValue *get_compTM (lua_State *L, Table *mt1, Table *mt2,

                                  TMS event) {

  const TValue *tm1 = fasttm(L, mt1, event);

  const TValue *tm2;

  if (tm1 == NULL) return NULL;  /* no metamethod */

  if (mt1 == mt2) return tm1;  /* same metatables => same metamethods */

  tm2 = fasttm(L, mt2, event);

  if (tm2 == NULL) return NULL;  /* no metamethod */

  if (luaO_rawequalObj(tm1, tm2))  /* same metamethods? */

    return tm1;

  return NULL;

}

static int call_orderTM (lua_State *L, const TValue *p1, const TValue *p2,

                         TMS event) {

  const TValue *tm1 = luaT_gettmbyobj(L, p1, event);

  const TValue *tm2;

  if (ttisnil(tm1)) return -1;  /* no metamethod? */

  tm2 = luaT_gettmbyobj(L, p2, event);

  if (!luaO_rawequalObj(tm1, tm2))  /* different metamethods? */

    return -1;

  callTMres(L, L->top, tm1, p1, p2);

  return !l_isfalse(L->top);

}

static int l_strcmp (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;

    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 (len == ll) ? 0 : 1;

      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 TValue *l, const TValue *r) {

  int res;

  if (ttype(l) != ttype(r))

    return luaG_ordererror(L, l, r);

  else if (ttisnumber(l))

    return luai_numlt(nvalue(l), nvalue(r));

  else if (ttisstring(l))

    return l_strcmp(rawtsvalue(l), rawtsvalue(r)) < 0;

  else if ((res = call_orderTM(L, l, r, TM_LT)) != -1)

    return res;

  return luaG_ordererror(L, l, r);

}

static int lessequal (lua_State *L, const TValue *l, const TValue *r) {

  int res;

  if (ttype(l) != ttype(r))

    return luaG_ordererror(L, l, r);

  else if (ttisnumber(l))

    return luai_numle(nvalue(l), nvalue(r));

  else if (ttisstring(l))

    return l_strcmp(rawtsvalue(l), rawtsvalue(r)) <= 0;

  else if ((res = call_orderTM(L, l, r, TM_LE)) != -1)  /* first try `le' */

    return res;

  else if ((res = call_orderTM(L, r, l, TM_LT)) != -1)  /* else try `lt' */

    return !res;

  return luaG_ordererror(L, l, r);

}

int luaV_equalval (lua_State *L, const TValue *t1, const TValue *t2) {

  const TValue *tm;

  lua_assert(ttype(t1) == ttype(t2));

  switch (ttype(t1)) {

    case LUA_TNIL: return 1;

    case LUA_TNUMBER: return luai_numeq(nvalue(t1), nvalue(t2));

    case LUA_TBOOLEAN: return bvalue(t1) == bvalue(t2);  /* true must be 1 !! */

    case LUA_TLIGHTUSERDATA: return pvalue(t1) == pvalue(t2);

    case LUA_TUSERDATA: {

      if (uvalue(t1) == uvalue(t2)) return 1;

      tm = get_compTM(L, uvalue(t1)->metatable, uvalue(t2)->metatable,

                         TM_EQ);

      break;  /* will try TM */

    }

    case LUA_TTABLE: {

      if (hvalue(t1) == hvalue(t2)) return 1;

      tm = get_compTM(L, hvalue(t1)->metatable, hvalue(t2)->metatable, TM_EQ);

      break;  /* will try TM */

    }

    default: return gcvalue(t1) == gcvalue(t2);

  }

  if (tm == NULL) return 0;  /* no TM? */

  callTMres(L, L->top, tm, t1, t2);  /* call TM */

  return !l_isfalse(L->top);

}

void luaV_concat (lua_State *L, int total, int last) {

  do {

    StkId top = L->base + last + 1;

    int n = 2;  /* number of elements handled in this pass (at least 2) */

    if (!(ttisstring(top-2) || ttisnumber(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)->len == 0)  /* second op is empty? */

      (void)tostring(L, top - 2);  /* result is first op (as string) */

    else {

      /* at least two string values; get as many as possible */

      size_t tl = tsvalue(top-1)->len;

      char *buffer;

      int i;

      /* collect total length */

      for (n = 1; n < total && tostring(L, top-n-1); n++) {

        size_t l = tsvalue(top-n-1)->len;

        if (l >= MAX_SIZET - tl) luaG_runerror(L, "string length overflow");

        tl += l;

      }

      buffer = luaZ_openspace(L, &G(L)->buff, tl);

      tl = 0;

      for (i=n; i>0; i--) {  /* concat all strings */

        size_t l = tsvalue(top-i)->len;

        memcpy(buffer+tl, svalue(top-i), l);

        tl += l;

      }

      setsvalue2s(L, 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 Arith (lua_State *L, StkId ra, const TValue *rb,

                   const TValue *rc, TMS op) {

  TValue tempb, tempc;

  const TValue *b, *c;

  if ((b = luaV_tonumber(rb, &tempb)) != NULL &&

      (c = luaV_tonumber(rc, &tempc)) != NULL) {

    lua_Number nb = nvalue(b), nc = nvalue(c);

    switch (op) {

      case TM_ADD: setnvalue(ra, luai_numadd(nb, nc)); break;

      case TM_SUB: setnvalue(ra, luai_numsub(nb, nc)); break;

      case TM_MUL: setnvalue(ra, luai_nummul(nb, nc)); break;

      case TM_DIV: setnvalue(ra, luai_numdiv(nb, nc)); break;

      case TM_MOD: setnvalue(ra, luai_nummod(nb, nc)); break;

      case TM_POW: setnvalue(ra, luai_numpow(nb, nc)); break;

      case TM_UNM: setnvalue(ra, luai_numunm(nb)); break;

      default: lua_assert(0); break;

    }

  }

  else if (!call_binTM(L, rb, rc, ra, op))

    luaG_aritherror(L, rb, rc);

}

/*

** some macros for common tasks in `luaV_execute'

*/

#define runtime_check(L, c) { if (!(c)) break; }

#define RA(i)   (base+GETARG_A(i))

/* to be used after possible stack reallocation */

#define RB(i)   check_exp(getBMode(GET_OPCODE(i)) == OpArgR, base+GETARG_B(i))

#define RC(i)   check_exp(getCMode(GET_OPCODE(i)) == OpArgR, base+GETARG_C(i))

#define RKB(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, \

    ISK(GETARG_B(i)) ? k+INDEXK(GETARG_B(i)) : base+GETARG_B(i))

#define RKC(i)  check_exp(getCMode(GET_OPCODE(i)) == OpArgK, \

    ISK(GETARG_C(i)) ? k+INDEXK(GETARG_C(i)) : base+GETARG_C(i))

#define KBx(i)  check_exp(getBMode(GET_OPCODE(i)) == OpArgK, k+GETARG_Bx(i))

#define dojump(L,pc,i)  {(pc) += (i); luai_threadyield(L);}

#define Protect(x)  { L->savedpc = pc; {x;}; base = L->base; }

#define arith_op(op,tm) { \

        TValue *rb = RKB(i); \

        TValue *rc = RKC(i); \

        if (ttisnumber(rb) && ttisnumber(rc)) { \

          lua_Number nb = nvalue(rb), nc = nvalue(rc); \

          setnvalue(ra, op(nb, nc)); \

        } \

        else \

          Protect(Arith(L, ra, rb, rc, tm)); \

      }

void luaV_execute (lua_State *L, int nexeccalls) {

  LClosure *cl;

  StkId base;

  TValue *k;

  const Instruction *pc;

 reentry:  /* entry point */

  lua_assert(isLua(L->ci));

  pc = L->savedpc;

  cl = &clvalue(L->ci->func)->l;

  base = L->base;

  k = cl->p->k;

  /* main loop of interpreter */

  for (;;) {

    const Instruction i = *pc++;

    StkId ra;

    if ((L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) &&

        (--L->hookcount == 0 || L->hookmask & LUA_MASKLINE)) {

      traceexec(L, pc);

      if (L->status == LUA_YIELD) {  /* did hook yield? */

        L->savedpc = pc - 1;

        return;

      }

      base = L->base;

    }

    /* warning!! several calls may realloc the stack and invalidate `ra' */

    ra = RA(i);

    lua_assert(base == L->base && L->base == L->ci->base);

    lua_assert(base <= L->top && L->top <= L->stack + L->stacksize);

    lua_assert(L->top == L->ci->top || luaG_checkopenop(i));

    switch (GET_OPCODE(i)) {

      case OP_MOVE: {

        setobjs2s(L, ra, RB(i));

        continue;

      }

      case OP_LOADK: {

        setobj2s(L, ra, KBx(i));

        continue;

      }

      case OP_LOADBOOL: {

        setbvalue(ra, GETARG_B(i));

        if (GETARG_C(i)) pc++;  /* skip next instruction (if C) */

        continue;

      }

      case OP_LOADNIL: {

        TValue *rb = RB(i);

        do {

          setnilvalue(rb--);

        } while (rb >= ra);

        continue;

      }

      case OP_GETUPVAL: {

        int b = GETARG_B(i);

        setobj2s(L, ra, cl->upvals[b]->v);

        continue;

      }

      case OP_GETGLOBAL: {

        TValue g;

        TValue *rb = KBx(i);

        sethvalue(L, &g, cl->env);

        lua_assert(ttisstring(rb));

        Protect(luaV_gettable(L, &g, rb, ra));

        continue;

      }

      case OP_GETTABLE: {

        Protect(luaV_gettable(L, RB(i), RKC(i), ra));

        continue;

      }

      case OP_SETGLOBAL: {

        TValue g;

        sethvalue(L, &g, cl->env);

        lua_assert(ttisstring(KBx(i)));

        Protect(luaV_settable(L, &g, KBx(i), ra));

        continue;

      }

      case OP_SETUPVAL: {

        UpVal *uv = cl->upvals[GETARG_B(i)];

        setobj(L, uv->v, ra);

        luaC_barrier(L, uv, ra);

        continue;

      }

      case OP_SETTABLE: {

        Protect(luaV_settable(L, ra, RKB(i), RKC(i)));

        continue;

      }

      case OP_NEWTABLE: {

        int b = GETARG_B(i);

        int c = GETARG_C(i);

        sethvalue(L, ra, luaH_new(L, luaO_fb2int(b), luaO_fb2int(c)));

        Protect(luaC_checkGC(L));

        continue;

      }

      case OP_SELF: {

        StkId rb = RB(i);

        setobjs2s(L, ra+1, rb);

        Protect(luaV_gettable(L, rb, RKC(i), ra));

        continue;

      }

      case OP_ADD: {

        arith_op(luai_numadd, TM_ADD);

        continue;

      }

      case OP_SUB: {

        arith_op(luai_numsub, TM_SUB);

        continue;

      }

      case OP_MUL: {

        arith_op(luai_nummul, TM_MUL);

        continue;

      }

      case OP_DIV: {

        arith_op(luai_numdiv, TM_DIV);

        continue;

      }

      case OP_MOD: {

        arith_op(luai_nummod, TM_MOD);

        continue;

      }

      case OP_POW: {

        arith_op(luai_numpow, TM_POW);

        continue;

      }

      case OP_UNM: {

        TValue *rb = RB(i);

        if (ttisnumber(rb)) {

          lua_Number nb = nvalue(rb);

          setnvalue(ra, luai_numunm(nb));

        }

        else {

          Protect(Arith(L, ra, rb, rb, TM_UNM));

        }

        continue;

      }

      case OP_NOT: {

        int res = l_isfalse(RB(i));  /* next assignment may change this value */

        setbvalue(ra, res);

        continue;

      }

      case OP_LEN: {

        const TValue *rb = RB(i);

        switch (ttype(rb)) {

          case LUA_TTABLE: {

            setnvalue(ra, cast_num(luaH_getn(hvalue(rb))));

            break;

          }

          case LUA_TSTRING: {

            setnvalue(ra, cast_num(tsvalue(rb)->len));

            break;

          }

          default: {  /* try metamethod */

            Protect(

              if (!call_binTM(L, rb, luaO_nilobject, ra, TM_LEN))

                luaG_typeerror(L, rb, "get length of");

            )

          }

        }