text: /*
  ** $Id: lvm.c,v 2.63.1.4 2009/07/01 21:10:33 roberto Exp $
  ** Lua virtual machine
  ** See Copyright Notice in lua.h
  */
  
  #define lvm_c
  #define LUA_CORE
  #define LUAC_CROSS_FILE
  
  #include "lua.h"
  #include C_HEADER_STDIO
  #include C_HEADER_STRING
  #include C_HEADER_MATH
  
  #include "ldebug.h"
  #include "ldo.h"
  #include "lfunc.h"
  #include "lgc.h"
  #include "lobject.h"
  #include "lopcodes.h"
  #include "lrotable.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
  
  #if defined LUA_NUMBER_INTEGRAL
  LUA_NUMBER luai_ipow(LUA_NUMBER a, LUA_NUMBER b)
  {
      if (b < 0)
          return 0;
      else if (b == 0)
          return 1;
      else
      {
          LUA_NUMBER c = 1;
          for (;;)
          {
              if (b & 1)
                  c *= a;
              b = b >> 1;
              if (b == 0)
                  return c;
              a *= a;
          }
      }
  }
  #endif
  
  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];
          ptrdiff_t objr = savestack(L, obj);
          lua_Number n = nvalue(obj);
          lua_number2str(s, n);
          setsvalue2s(L, restorestack(L, objr), 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;
      TValue temp;
      for (loop = 0; loop < MAXTAGLOOP; loop++)
      {
          const TValue *tm;
          if (ttistable(t) || ttisrotable(t))
          { /* `t' is a table? */
              void *h = ttistable(t) ? hvalue(t) : rvalue(t);
              const TValue *res = ttistable(t) ? luaH_get((Table *)h, key) : luaH_get_ro(h, key); /* do a primitive get */
              if (!ttisnil(res) ||                                                                /* result is no nil? */
                  (tm = fasttm(L, ttistable(t) ? ((Table *)h)->metatable : (Table *)luaR_getmeta(h), 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) || ttislightfunction(tm))
          {
              callTMres(L, val, tm, t, key);
              return;
          }
          /* else repeat with `tm' */
          setobj(L, &temp, tm); /* avoid pointing inside table (may rehash) */
          t = &temp;
      }
      luaG_runerror(L, "loop in gettable");
  }
  
  void luaV_settable(lua_State *L, const TValue *t, TValue *key, StkId val)
  {
      int loop;
      TValue temp;
      setnilvalue(L->top);
      L->top++;
      fixedstack(L);
      for (loop = 0; loop < MAXTAGLOOP; loop++)
      {
          const TValue *tm;
          if (ttistable(t) || ttisrotable(t))
          { /* `t' is a table? */
              void *h = ttistable(t) ? hvalue(t) : rvalue(t);
              TValue *oldval = ttistable(t) ? luaH_set(L, (Table *)h, key) : NULL; /* do a primitive set */
              if ((oldval && !ttisnil(oldval)) ||                                  /* result is no nil? */
                  (tm = fasttm(L, ttistable(t) ? ((Table *)h)->metatable : (Table *)luaR_getmeta(h), TM_NEWINDEX)) ==
                      NULL)
              { /* or no TM? */
                  if (oldval)
                  {
                      L->top--;
                      unfixedstack(L);
                      setobj2t(L, oldval, val);
                      ((Table *)h)->flags = 0;
                      luaC_barriert(L, (Table *)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) || ttislightfunction(tm))
          {
              L->top--;
              unfixedstack(L);
              callTM(L, tm, t, key, val);
              return;
          }
          /* else repeat with `tm' */
          setobj(L, &temp, tm); /* avoid pointing inside table (may rehash) */
          t = &temp;
          setobj2s(L, L->top - 1, t); /* need to protect value from EGC. */
      }
      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:
          case LUA_TROTABLE:
          case LUA_TLIGHTFUNCTION:
              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)
  {
      lu_mem max_sizet = MAX_SIZET;
      if (G(L)->memlimit < max_sizet)
          max_sizet = G(L)->memlimit;
      do
      {
          /* Any call which does a memory allocation may trim the stack,
             invalidating top unless the stack is fixed duri  ng the allocation */
          StkId top = L->base + last + 1;
          fixedstack(L);
          int n = 2; /* number of elements handled in this pass (at least 2) */
          if (!(ttisstring(top - 2) || ttisnumber(top - 2)) || !tostring(L, top - 1))
          {
              unfixedstack(L);
              if (!call_binTM(L, top - 2, top - 1, top - 2, TM_CONCAT))
              {
                  /* restore 'top' pointer, since stack might have been reallocted
                   */
                  top = L->base + last + 1;
                  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;
              }
              G(L)->buff.n = tl;
              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));
              luaZ_resetbuffer(&G(L)->buff);
          }
          total -= n - 1; /* got `n' strings to create 1 new */
          last -= n - 1;
          unfixedstack(L);
      } 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_lnumdiv(nb, nc));
                  break;
              case TM_MOD:
                  setnvalue(ra, luai_lnummod(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
      {
          ptrdiff_t br = savestack(L, rb);
          ptrdiff_t cr = savestack(L, rc);
          if (!call_binTM(L, rb, rc, ra, op))
          {
              luaG_aritherror(L, restorestack(L, br), restorestack(L, cr));
          }
      }
  }
  
  /*
  ** 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);
                  Table *h;
                  Protect(h = luaH_new(L, luaO_fb2int(b), luaO_fb2int(c)));
                  sethvalue(L, RA(i), h);
                  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_lnumdiv, TM_DIV);
                  continue;
              }
              case OP_MOD:
              {
                  arith_op(luai_lnummod, 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:
                      case LUA_TROTABLE:
                      {
                          setnvalue(ra,
                                    ttistable(rb) ? cast_num(luaH_getn(hvalue(rb))) : cast_num(luaH_getn_ro(rvalue(rb))));
                          break;
                      }
                      case LUA_TSTRING:
                      {
                          setnvalue(ra, cast_num(tsvalue(rb)->len));
                          break;
                      }
                      default:
                      { /* try metamethod */
                          ptrdiff_t br = savestack(L, rb);
                          Protect(if (!call_binTM(L, rb, luaO_nilobject, ra, TM_LEN))
                                      luaG_typeerror(L, restorestack(L, br), "get length of");)
                      }
                  }
                  continue;
              }
              case OP_CONCAT:
              {
                  int b = GETARG_B(i);
                  int c = GETARG_C(i);
                  Protect(luaV_concat(L, c - b + 1, c); luaC_checkGC(L));
                  setobjs2s(L, RA(i), base + b);
                  continue;
              }
              case OP_JMP:
              {
                  dojump(L, pc, GETARG_sBx(i));
                  continue;
              }
              case OP_EQ:
              {
                  TValue *rb = RKB(i);
                  TValue *rc = RKC(i);
                  Protect(if (equalobj(L, rb, rc) == GETARG_A(i)) dojump(L, pc, GETARG_sBx(*pc));) pc++;
                  continue;
              }
              case OP_LT:
              {
                  Protect(if (luaV_lessthan(L, RKB(i), RKC(i)) == GETARG_A(i)) dojump(L, pc, GETARG_sBx(*pc));) pc++;
                  continue;
              }
              case OP_LE:
              {
                  Protect(if (lessequal(L, RKB(i), RKC(i)) == GETARG_A(i)) dojump(L, pc, GETARG_sBx(*pc));) pc++;
                  continue;
              }
              case OP_TEST:
              {
                  if (l_isfalse(ra) != GETARG_C(i))
                      dojump(L, pc, GETARG_sBx(*pc));
                  pc++;
                  continue;
              }
              case OP_TESTSET:
              {
                  TValue *rb = RB(i);
                  if (l_isfalse(rb) != GETARG_C(i))
                  {
                      setobjs2s(L, ra, rb);
                      dojump(L, pc, GETARG_sBx(*pc));
                  }
                  pc++;
                  continue;
              }
              case OP_CALL:
              {
                  int b = GETARG_B(i);
                  int nresults = GETARG_C(i) - 1;
                  if (b != 0)
                      L->top = ra + b; /* else previous instruction set top */
                  L->savedpc = pc;
                  switch (luaD_precall(L, ra, nresults))
                  {
                      case PCRLUA:
                      {
                          nexeccalls++;
                          goto reentry; /* restart luaV_execute over new Lua
                                           function */
                      }
                      case PCRC:
                      {
                          /* it was a C function (`precall' called it); adjust
                           * results */
                          if (nresults >= 0)
                              L->top = L->ci->top;
                          base = L->base;
                          continue;
                      }
                      default:
                      {
                          return; /* yield */
                      }
                  }
              }
              case OP_TAILCALL:
              {
                  int b = GETARG_B(i);
                  if (b != 0)
                      L->top = ra + b; /* else previous instruction set top */
                  L->savedpc = pc;
                  lua_assert(GETARG_C(i) - 1 == LUA_MULTRET);
                  switch (luaD_precall(L, ra, LUA_MULTRET))
                  {
                      case PCRLUA:
                      {
                          /* tail call: put new frame in place of previous one */
                          CallInfo *ci = L->ci - 1; /* previous frame */
                          int aux;
                          StkId func = ci->func;
                          StkId pfunc = (ci + 1)->func; /* previous function index */
                          if (L->openupval)
                              luaF_close(L, ci->base);
                          L->base = ci->base = ci->func + ((ci + 1)->base - pfunc);
                          for (aux = 0; pfunc + aux < L->top; aux++) /* move frame down */
                              setobjs2s(L, func + aux, pfunc + aux);
                          ci->top = L->top = func + aux; /* correct top */
                          lua_assert(L->top == L->base + clvalue(func)->l.p->maxstacksize);
                          ci->savedpc = L->savedpc;
                          ci->tailcalls++; /* one more call lost */
                          L->ci--;         /* remove new frame */
                          goto reentry;
                      }
                      case PCRC:
                      { /* it was a C function (`precall' called it) */
                          base = L->base;
                          continue;
                      }
                      default:
                      {
                          return; /* yield */
                      }
                  }
              }
              case OP_RETURN:
              {
                  int b = GETARG_B(i);
                  if (b != 0)
                      L->top = ra + b - 1;
                  if (L->openupval)
                      luaF_close(L, base);
                  L->savedpc = pc;
                  b = luaD_poscall(L, ra);
                  if (--nexeccalls == 0) /* was previous function running `here'? */
                      return;            /* no: return */
                  else
                  { /* yes: continue its execution */
                      if (b)
                          L->top = L->ci->top;
                      lua_assert(isLua(L->ci));
                      lua_assert(GET_OPCODE(*((L->ci)->savedpc - 1)) == OP_CALL);
                      goto reentry;
                  }
              }
              case OP_FORLOOP:
              {
                  lua_Number step = nvalue(ra + 2);
                  lua_Number idx = luai_numadd(nvalue(ra), step); /* increment index */
                  lua_Number limit = nvalue(ra + 1);
                  if (luai_numlt(0, step) ? luai_numle(idx, limit) : luai_numle(limit, idx))
                  {
                      dojump(L, pc, GETARG_sBx(i)); /* jump back */
                      setnvalue(ra, idx);           /* update internal index... */
                      setnvalue(ra + 3, idx);       /* ...and external index */
                  }
                  continue;
              }
              case OP_FORPREP:
              {
                  const TValue *init = ra;
                  const TValue *plimit = ra + 1;
                  const TValue *pstep = ra + 2;
                  L->savedpc = pc; /* next steps may throw errors */
                  if (!tonumber(init, ra))
                      luaG_runerror(L, LUA_QL("for") " initial value must be a number");
                  else if (!tonumber(plimit, ra + 1))
                      luaG_runerror(L, LUA_QL("for") " limit must be a number");
                  else if (!tonumber(pstep, ra + 2))
                      luaG_runerror(L, LUA_QL("for") " step must be a number");
                  setnvalue(ra, luai_numsub(nvalue(ra), nvalue(pstep)));
                  dojump(L, pc, GETARG_sBx(i));
                  continue;
              }
              case OP_TFORLOOP:
              {
                  StkId cb = ra + 3; /* call base */
                  setobjs2s(L, cb + 2, ra + 2);
                  setobjs2s(L, cb + 1, ra + 1);
                  setobjs2s(L, cb, ra);
                  L->top = cb + 3; /* func. + 2 args (state and index) */
                  Protect(luaD_call(L, cb, GETARG_C(i)));
                  L->top = L->ci->top;
                  cb = RA(i) + 3; /* previous call may change the stack */
                  if (!ttisnil(cb))
                  {                                   /* continue loop? */
                      setobjs2s(L, cb - 1, cb);       /* save control variable */
                      dojump(L, pc, GETARG_sBx(*pc)); /* jump back */
                  }
                  pc++;
                  continue;
              }
              case OP_SETLIST:
              {
                  int n = GETARG_B(i);
                  int c = GETARG_C(i);
                  int last;
                  Table *h;
                  fixedstack(L);
                  if (n == 0)
                  {
                      n = cast_int(L->top - ra) - 1;
                  }
                  if (c == 0)
                      c = cast_int(*pc++);
                  runtime_check(L, ttistable(ra));
                  h = hvalue(ra);
                  last = ((c - 1) * LFIELDS_PER_FLUSH) + n;
                  if (last > h->sizearray)          /* needs more space? */
                      luaH_resizearray(L, h, last); /* pre-alloc it at once */
                  for (; n > 0; n--)
                  {
                      TValue *val = ra + n;
                      setobj2t(L, luaH_setnum(L, h, last--), val);
                      luaC_barriert(L, h, val);
                  }
                  L->top = L->ci->top;
                  unfixedstack(L);
                  continue;
              }
              case OP_CLOSE:
              {
                  luaF_close(L, ra);
                  continue;
              }
              case OP_CLOSURE:
              {
                  Proto *p;
                  Closure *ncl;
                  int nup, j;
                  p = cl->p->p[GETARG_Bx(i)];
                  nup = p->nups;
                  fixedstack(L);
                  ncl = luaF_newLclosure(L, nup, cl->env);
                  setclvalue(L, ra, ncl);
                  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));
                      }
                  }
                  unfixedstack(L);
                  Protect(luaC_checkGC(L));
                  continue;
              }
              case OP_VARARG:
              {
                  int b = GETARG_B(i) - 1;
                  int j;
                  CallInfo *ci = L->ci;
                  int n = cast_int(ci->base - ci->func) - cl->p->numparams - 1;
                  if (b == LUA_MULTRET)
                  {
                      Protect(luaD_checkstack(L, n));
                      ra = RA(i); /* previous call may change the stack */
                      b = n;
                      L->top = ra + n;
                  }
                  for (j = 0; j < b; j++)
                  {
                      if (j < n)
                      {
                          setobjs2s(L, ra + j, ci->base - n + j);
                      }
                      else
                      {
                          setnilvalue(ra + j);
                      }
                  }
                  continue;
              }
          }
      }
  }
  