games/minimal/mods/default/textures/default_mineral_coal.png

/*
** $Id: lapi.c,v 2.55.1.5 2008/07/04 18:41:18 roberto Exp $
** Lua API
** See Copyright Notice in lua.h
*/


#include <assert.h>
#include <math.h>
#include <stdarg.h>
#include <string.h>

#define lapi_c
#define LUA_CORE

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lundump.h"
#include "lvm.h"


const char lua_ident[] =
  "$Lua: " LUA_RELEASE " " LUA_COPYRIGHT " $\n"
  "$Authors: " LUA_AUTHORS " $\n"
  "$URL: www.lua.org $\n";


#define api_checknelems(L, n)	api_check(L, (n) <= (L->top - L->base))

#define api_checkvalidindex(L, i)	api_check(L, (i) != luaO_nilobject)

#define api_incr_top(L)   {api_check(L, L->top < L->ci->top); L->top++;}


static TValue *index2adr (lua_State *L, int idx) {
  if (idx > 0) {
    TValue *o = L->base + (idx - 1);
    api_check(L, idx <= L->ci->top - L->base);
    if (o >= L->top) return cast(TValue *, luaO_nilobject);
    else return o;
  }
  else if (idx > LUA_REGISTRYINDEX) {
    api_check(L, idx != 0 && -idx <= L->top - L->base);
    return L->top + idx;
  }
  else switch (idx) {  /* pseudo-indices */
    case LUA_REGISTRYINDEX: return registry(L);
    case LUA_ENVIRONINDEX: {
      Closure *func = curr_func(L);
      sethvalue(L, &L->env, func->c.env);
      return &L->env;
    }
    case LUA_GLOBALSINDEX: return gt(L);
    default: {
      Closure *func = curr_func(L);
      idx = LUA_GLOBALSINDEX - idx;
      return (idx <= func->c.nupvalues)
                ? &func->c.upvalue[idx-1]
                : cast(TValue *, luaO_nilobject);
    }
  }
}


static Table *getcurrenv (lua_State *L) {
  if (L->ci == L->base_ci)  /* no enclosing function? */
    return hvalue(gt(L));  /* use global table as environment */
  else {
    Closure *func = curr_func(L);
    return func->c.env;
  }
}


void luaA_pushobject (lua_State *L, const TValue *o) {
  setobj2s(L, L->top, o);
  api_incr_top(L);
}


LUA_API int lua_checkstack (lua_State *L, int size) {
  int res = 1;
  lua_lock(L);
  if (size > LUAI_MAXCSTACK || (L->top - L->base + size) > LUAI_MAXCSTACK)
    res = 0;  /* stack overflow */
  else if (size > 0) {
    luaD_checkstack(L, size);
    if (L->ci->top < L->top + size)
      L->ci->top = L->top + size;
  }
  lua_unlock(L);
  return res;
}


LUA_API void lua_xmove (lua_State *from, lua_State *to, int n) {
  int i;
  if (from == to) return;
  lua_lock(to);
  api_checknelems(from, n);
  api_check(from, G(from) == G(to));
  api_check(from, to->ci->top - to->top >= n);
  from->top -= n;
  for (i = 0; i < n; i++) {
    setobj2s(to, to->top++, from->top + i);
  }
  lua_unlock(to);
}


LUA_API void lua_setlevel (lua_State *from, lua_State *to) {
  to->nCcalls = from->nCcalls;
}


LUA_API lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf) {
  lua_CFunction old;
  lua_lock(L);
  old = G(L)->panic;
  G(L)->panic = panicf;
  lua_unlock(L);
  return old;
}


LUA_API lua_State *lua_newthread (lua_State *L) {
  lua_State *L1;
  lua_lock(L);
  luaC_checkGC(L);
  L1 = luaE_newthread(L);
  setthvalue(L, L->top, L1);
  api_incr_top(L);
  lua_unlock(L);
  luai_userstatethread(L, L1);
  return L1;
}


/*
** basic stack manipulation
*/


LUA_API int lua_gettop (lua_State *L) {
  return cast_int(L->top - L->base);
}


LUA_API void lua_settop (lua_State *L, int idx) {
  lua_lock(L);
  if (idx >= 0) {
    api_check(L, idx <= L->stack_last - L->base);
    while (L->top < L->base + idx)
      setnilvalue(L->top++);
    L->top = L->base + idx;
  }
  else {
    api_check(L, -(idx+1) <= (L->top - L->base));
    L->top += idx+1;  /* `subtract' index (index is negative) */
  }
  lua_unlock(L);
}


LUA_API void lua_remove (lua_State *L, int idx) {
  StkId p;
  lua_lock(L);
  p = index2adr(L, idx);
  api_checkvalidindex(L, p);
  while (++p < L->top) setobjs2s(L, p-1, p);
  L->top--;
  lua_unlock(L);
}


LUA_API void lua_insert (lua_State *L, int idx) {
  StkId p;
  StkId q;
  lua_lock(L);
  p = index2adr(L, idx);
  api_checkvalidindex(L, p);
  for (q = L->top; q>p; q--) setobjs2s(L, q, q-1);
  setobjs2s(L, p, L->top);
  lua_unlock(L);
}


LUA_API void lua_replace (lua_State *L, int idx) {
  StkId o;
  lua_lock(L);
  /* explicit test for incompatible code */
  if (idx == LUA_ENVIRONINDEX && L->ci == L->base_ci)
    luaG_runerror(L, "no calling environment");
  api_checknelems(L, 1);
  o = index2adr(L, idx);
  api_checkvalidindex(L, o);
  if (idx == LUA_ENVIRONINDEX) {
    Closure *func = curr_func(L);
    api_check(L, ttistable(L->top - 1)); 
    func->c.env = hvalue(L->top - 1);
    luaC_barrier(L, func, L->top - 1);
  }
  else {
    setobj(L, o, L->top - 1);
    if (idx < LUA_GLOBALSINDEX)  /* function upvalue? */
      luaC_barrier(L, curr_func(L), L->top - 1);
  }
  L->top--;
  lua_unlock(L);
}


LUA_API void lua_pushvalue (lua_State *L, int idx) {
  lua_lock(L);
  setobj2s(L, L->top, index2adr(L, idx));
  api_incr_top(L);
  lua_unlock(L);
}


/*
** access functions (stack -> C)
*/


LUA_API int lua_type (lua_State *L, int idx) {
  StkId o = index2adr(L, idx);
  return (o == luaO_nilobject) ? LUA_TNONE : ttype(o);
}


LUA_API const char *lua_typename (lua_State *L, int t) {
  UNUSED(L);
  return (t == LUA_TNONE) ? "no value" : luaT_typenames[t];
}


LUA_API int lua_iscfunction (lua_State *L, int idx) {
  StkId o = index2adr(L, idx);
  return iscfunction(o);
}


LUA_API int lua_isnumber (lua_State *L, int idx) {
  TValue n;
  const TValue *o = index2adr(L, idx);
  return tonumber(o, &n);
}


LUA_API int lua_isstring (lua_State *L, int idx) {
  int t = lua_type(L, idx);
  return (t == LUA_TSTRING || t == LUA_TNUMBER);
}


LUA_API int lua_isuserdata (lua_State *L, int idx) {
  const TValue *o = index2adr(L, idx);
  return (ttisuserdata(o) || ttislightuserdata(o));
}


LUA_API int lua_rawequal (lua_State *L, int index1, int index2) {
  StkId o1 = index2adr(L, index1);
  StkId o2 = index2adr(L, index2);
  return (o1 == luaO_nilobject || o2 == luaO_nilobject) ? 0
         : luaO_rawequalObj(o1, o2);
}


LUA_API int lua_equal (lua_State *L, int index1, int index2) {
  StkId o1, o2;
  int i;
  lua_lock(L);  /* may call tag method */
  o1 = index2adr(L, index1);
  o2 = index2adr(L, index2);
  i = (o1 == luaO_nilobject || o2 == luaO_nilobject) ? 0 : equalobj(L, o1, o2);
  lua_unlock(L);
  return i;
}


LUA_API int lua_lessthan (lua_State *L, int index1, int index2) {
  StkId o1, o2;
  int i;
  lua_lock(L);  /* may call tag method */
  o1 = index2adr(L, index1);
  o2 = index2adr(L, index2);
  i = (o1 == luaO_nilobject || o2 == luaO_nilobject) ? 0
       : luaV_lessthan(L, o1, o2);
  lua_unlock(L);
  return i;
}


LUA_API lua_Number lua_tonumber (lua_State *L, int idx) {
  TValue n;
  const TValue *o = index2adr(L, idx);
  if (tonumber(o, &n))
    return nvalue(o);
  else
    return 0;
}


LUA_API lua_Integer lua_tointeger (lua_State *L, int idx) {
  TValue n;
  const TValue *o = index2adr(L, idx);
  if (tonumber(o, &n)) {
    lua_Integer res;
    lua_Number num = nvalue(o);
    lua_number2integer(res, num);
    return res;
  }
  else
    return 0;
}


LUA_API int lua_toboolean (lua_State *L, int idx) {
  const TValue *o = index2adr(L, idx);
  return !l_isfalse(o);
}


LUA_API const char *lua_tolstring (lua_State *L, int idx, size_t *len) {
  StkId o = index2adr(L, idx);
  if (!ttisstring(o)) {
    lua_lock(L);  /* `luaV_tostring' may create a new string */
    if (!luaV_tostring(L, o)) {  /* conversion failed? */
      if (len != NULL) *len = 0;
      lua_unlock(L);
      return NULL;
    }
    luaC_checkGC(L);
    o = index2adr(L, idx);  /* previous call may reallocate the stack */
    lua_unlock(L);
  }
  if (len != NULL) *len = tsvalue(o)->len;
  return svalue(o);
}


LUA_API size_t lua_objlen (lua_State *L, int idx) {
  StkId o = index2adr(L, idx);
  switch (ttype(o)) {
    case LUA_TSTRING: return tsvalue(o)->len;
    case LUA_TUSERDATA: return uvalue(o)->len;
    case LUA_TTABLE: return luaH_getn(hvalue(o));
    case LUA_TNUMBER: {
      size_t l;
      lua_lock(L);  /* `luaV_tostring' may create a new string */
      l = (luaV_tostring(L, o) ? tsvalue(o)->len : 0);
      lua_unlock(L);
      return l;
    }
    default: return 0;
  }
}


LUA_API lua_CFunction lua_tocfunction (lua_State *L, int idx) {
  StkId o = index2adr(L, idx);
  return (!iscfunction(o)) ? NULL : clvalue(o)->c.f;
}


LUA_API void *lua_touserdata (lua_State *L, int idx) {
  StkId o = index2adr(L, idx);
  switch (ttype(o)) {
    case LUA_TUSERDATA: return (rawuvalue(o) + 1);
    case LUA_TLIGHTUSERDATA: return pvalue(o);
    default: return NULL;
  }
}


LUA_API lua_State *lua_tothread (lua_State *L, int idx) {
  StkId o = index2adr(L, idx);
  return (!ttisthread(o)) ? NULL : thvalue(o);
}


LUA_API const void *lua_topointer (lua_State *L, int idx) {
  StkId o = index2adr(L, idx);
  switch (ttype(o)) {
    case LUA_TTABLE: return hvalue(o);
    case LUA_TFUNCTION: return clvalue(o);
    case LUA_TTHREAD: return thvalue(o);
    case LUA_TUSERDATA:
    case LUA_TLIGHTUSERDATA:
      return lua_touserdata(L, idx);
    default: return NULL;
  }
}


/*
** push functions (C -> stack)
*/


LUA_API void lua_pushnil (lua_State *L) {
  lua_lock(L);
  setnilvalue(L->top);
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_pushnumber (lua_State *L, lua_Number n) {
  lua_lock(L);
  setnvalue(L->top, n);
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_pushinteger (lua_State *L, lua_Integer n) {
  lua_lock(L);
  setnvalue(L->top, cast_num(n));
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_pushlstring (lua_State *L, const char *s, size_t len) {
  lua_lock(L);
  luaC_checkGC(L);
  setsvalue2s(L, L->top, luaS_newlstr(L, s, len));
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_pushstring (lua_State *L, const char *s) {
  if (s == NULL)
    lua_pushnil(L);
  else
    lua_pushlstring(L, s, strlen(s));
}


LUA_API const char *lua_pushvfstring (lua_State *L, const char *fmt,
                                      va_list argp) {
  const char *ret;
  lua_lock(L);
  luaC_checkGC(L);
  ret = luaO_pushvfstring(L, fmt, argp);
  lua_unlock(L);
  return ret;
}


LUA_API const char *lua_pushfstring (lua_State *L, const char *fmt, ...) {
  const char *ret;
  va_list argp;
  lua_lock(L);
  luaC_checkGC(L);
  va_start(argp, fmt);
  ret = luaO_pushvfstring(L, fmt, argp);
  va_end(argp);
  lua_unlock(L);
  return ret;
}


LUA_API void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n) {
  Closure *cl;
  lua_lock(L);
  luaC_checkGC(L);
  api_checknelems(L, n);
  cl = luaF_newCclosure(L, n, getcurrenv(L));
  cl->c.f = fn;
  L->top -= n;
  while (n--)
    setobj2n(L, &cl->c.upvalue[n], L->top+n);
  setclvalue(L, L->top, cl);
  lua_assert(iswhite(obj2gco(cl)));
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_pushboolean (lua_State *L, int b) {
  lua_lock(L);
  setbvalue(L->top, (b != 0));  /* ensure that true is 1 */
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_pushlightuserdata (lua_State *L, void *p) {
  lua_lock(L);
  setpvalue(L->top, p);
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API int lua_pushthread (lua_State *L) {
  lua_lock(L);
  setthvalue(L, L->top, L);
  api_incr_top(L);
  lua_unlock(L);
  return (G(L)->mainthread == L);
}


/*
** get functions (Lua -> stack)
*/


LUA_API void lua_gettable (lua_State *L, int idx) {
  StkId t;
  lua_lock(L);
  t = index2adr(L, idx);
  api_checkvalidindex(L, t);
  luaV_gettable(L, t, L->top - 1, L->top - 1);
  lua_unlock(L);
}


LUA_API void lua_getfield (lua_State *L, int idx, const char *k) {
  StkId t;
  TValue key;
  lua_lock(L);
  t = index2adr(L, idx);
  api_checkvalidindex(L, t);
  setsvalue(L, &key, luaS_new(L, k));
  luaV_gettable(L, t, &key, L->top);
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_rawget (lua_State *L, int idx) {
  StkId t;
  lua_lock(L);
  t = index2adr(L, idx);
  api_check(L, ttistable(t));
  setobj2s(L, L->top - 1, luaH_get(hvalue(t), L->top - 1));
  lua_unlock(L);
}


LUA_API void lua_rawgeti (lua_State *L, int idx, int n) {
  StkId o;
  lua_lock(L);
  o = index2adr(L, idx);
  api_check(L, ttistable(o));
  setobj2s(L, L->top, luaH_getnum(hvalue(o), n));
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_createtable (lua_State *L, int narray, int nrec) {
  lua_lock(L);
  luaC_checkGC(L);
  sethvalue(L, L->top, luaH_new(L, narray, nrec));
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API int lua_getmetatable (lua_State *L, int objindex) {
  const TValue *obj;
  Table *mt = NULL;
  int res;
  lua_lock(L);
  obj = index2adr(L, objindex);
  switch (ttype(obj)) {
    case LUA_TTABLE:
      mt = hvalue(obj)->metatable;
      break;
    case LUA_TUSERDATA:
      mt = uvalue(obj)->metatable;
      break;
    default:
      mt = G(L)->mt[ttype(obj)];
      break;
  }
  if (mt == NULL)
    res = 0;
  else {
    sethvalue(L, L->top, mt);
    api_incr_top(L);
    res = 1;
  }
  lua_unlock(L);
  return res;
}


LUA_API void lua_getfenv (lua_State *L, int idx) {
  StkId o;
  lua_lock(L);
  o = index2adr(L, idx);
  api_checkvalidindex(L, o);
  switch (ttype(o)) {
    case LUA_TFUNCTION:
      sethvalue(L, L->top, clvalue(o)->c.env);
      break;
    case LUA_TUSERDATA:
      sethvalue(L, L->top, uvalue(o)->env);
      break;
    case LUA_TTHREAD:
      setobj2s(L, L->top,  gt(thvalue(o)));
      break;
    default:
      setnilvalue(L->top);
      break;
  }
  api_incr_top(L);
  lua_unlock(L);
}


/*
** set functions (stack -> Lua)
*/


LUA_API void lua_settable (lua_State *L, int idx) {
  StkId t;
  lua_lock(L);
  api_checknelems(L, 2);
  t = index2adr(L, idx);
  api_checkvalidindex(L, t);
  luaV_settable(L, t, L->top - 2, L->top - 1);
  L->top -= 2;  /* pop index and value */
  lua_unlock(L);
}


LUA_API void lua_setfield (lua_State *L, int idx, const char *k) {
  StkId t;
  TValue key;
  lua_lock(L);
  api_checknelems(L, 1);
  t = index2adr(L, idx);
  api_checkvalidindex(L, t);
  setsvalue(L, &key, luaS_new(L, k));
  luaV_settable(L, t, &key, L->top - 1);
  L->top--;  /* pop value */
  lua_unlock(L);
}


LUA_API void lua_rawset (lua_State *L, int idx) {
  StkId t;
  lua_lock(L);
  api_checknelems(L, 2);
  t = index2adr(L, idx);
  api_check(L, ttistable(t));
  setobj2t(L, luaH_set(L, hvalue(t), L->top-2), L->top-1);
  luaC_barriert(L, hvalue(t), L->top-1);
  L->top -= 2;
  lua_unlock(L);
}


LUA_API void lua_rawseti (lua_State *L, int idx, int n) {
  StkId o;
  lua_lock(L);
  api_checknelems(L, 1);
  o = index2adr(L, idx);
  api_check(L, ttistable(o));
  setobj2t(L, luaH_setnum(L, hvalue(o), n), L->top-1);
  luaC_barriert(L, hvalue(o), L->top-1);
  L->top--;
  lua_unlock(L);
}


LUA_API int lua_setmetatable (lua_State *L, int objindex) {
  TValue *obj;
  Table *mt;
  lua_lock(L);
  api_checknelems(L, 1);
  obj = index2adr(L, objindex);
  api_checkvalidindex(L, obj);
  if (ttisnil(L->top - 1))
    mt = NULL;
  else {
    api_check(L, ttistable(L->top - 1));
    mt = hvalue(L->top - 1);
  }
  switch (ttype(obj)) {
    case LUA_TTABLE: {
      hvalue(obj)->metatable = mt;
      if (mt)
        luaC_objbarriert(L, hvalue(obj), mt);
      break;
    }
    case LUA_TUSERDATA: {
      uvalue(obj)->metatable = mt;
      if (mt)
        luaC_objbarrier(L, rawuvalue(obj), mt);
      break;
    }
    default: {
      G(L)->mt[ttype(obj)] = mt;
      break;
    }
  }
  L->top--;
  lua_unlock(L);
  return 1;
}


LUA_API int lua_setfenv (lua_State *L, int idx) {
  StkId o;
  int res = 1;
  lua_lock(L);
  api_checknelems(L, 1);
  o = index2adr(L, idx);
  api_checkvalidindex(L, o);
  api_check(L, ttistable(L->top - 1));
  switch (ttype(o)) {
    case LUA_TFUNCTION:
      clvalue(o)->c.env = hvalue(L->top - 1);
      break;
    case LUA_TUSERDATA:
      uvalue(o)->env = hvalue(L->top - 1);
      break;
    case LUA_TTHREAD:
      sethvalue(L, gt(thvalue(o)), hvalue(L->top - 1));
      break;
    default:
      res = 0;
      break;
  }
  if (res) luaC_objbarrier(L, gcvalue(o), hvalue(L->top - 1));
  L->top--;
  lua_unlock(L);
  return res;
}


/*
** `load' and `call' functions (run Lua code)
*/


#define adjustresults(L,nres) \
    { if (nres == LUA_MULTRET && L->top >= L->ci->top) L->ci->top = L->top; }


#define checkresults(L,na,nr) \
     api_check(L, (nr) == LUA_MULTRET || (L->ci->top - L->top >= (nr) - (na)))
	

LUA_API void lua_call (lua_State *L, int nargs, int nresults) {
  StkId func;
  lua_lock(L);
  api_checknelems(L, nargs+1);
  checkresults(L, nargs, nresults);
  func = L->top - (nargs+1);
  luaD_call(L, func, nresults);
  adjustresults(L, nresults);
  lua_unlock(L);
}


/*
** Execute a protected call.
*/
struct CallS {  /* data to `f_call' */
  StkId func;
  int nresults;
};


static void f_call (lua_State *L, void *ud) {
  struct CallS *c = cast(struct CallS *, ud);
  luaD_call(L, c->func, c->nresults);
}


LUA_API int lua_pcall (lua_State *L, int nargs, int nresults, int errfunc) {
  struct CallS c;
  int status;
  ptrdiff_t func;
  lua_lock(L);
  api_checknelems(L, nargs+1);
  checkresults(L, nargs, nresults);
  if (errfunc == 0)
    func = 0;
  else {
    StkId o = index2adr(L, errfunc);
    api_checkvalidindex(L, o);
    func = savestack(L, o);
  }
  c.func = L->top - (nargs+1);  /* function to be called */
  c.nresults = nresults;
  status = luaD_pcall(L, f_call, &c, savestack(L, c.func), func);
  adjustresults(L, nresults);
  lua_unlock(L);
  return status;
}


/*
** Execute a protected C call.
*/
struct CCallS {  /* data to `f_Ccall' */
  lua_CFunction func;
  void *ud;
};


static void f_Ccall (lua_State *L, void *ud) {
  struct CCallS *c = cast(struct CCallS *, ud);
  Closure *cl;
  cl = luaF_newCclosure(L, 0, getcurrenv(L));
  cl->c.f = c->func;
  setclvalue(L, L->top, cl);  /* push function */
  api_incr_top(L);
  setpvalue(L->top, c->ud);  /* push only argument */
  api_incr_top(L);
  luaD_call(L, L->top - 2, 0);
}


LUA_API int lua_cpcall (lua_State *L, lua_CFunction func, void *ud) {
  struct CCallS c;
  int status;
  lua_lock(L);
  c.func = func;
  c.ud = ud;
  status = luaD_pcall(L, f_Ccall, &c, savestack(L, L->top), 0);
  lua_unlock(L);
  return status;
}


LUA_API int lua_load (lua_State *L, lua_Reader reader, void *data,
                      const char *chunkname) {
  ZIO z;
  int status;
  lua_lock(L);
  if (!chunkname) chunkname = "?";
  luaZ_init(L, &z, reader, data);
  status = luaD_protectedparser(L, &z, chunkname);
  lua_unlock(L);
  return status;
}


LUA_API int lua_dump (lua_State *L, lua_Writer writer, void *data) {
  int status;
  TValue *o;
  lua_lock(L);
  api_checknelems(L, 1);
  o = L->top - 1;
  if (isLfunction(o))
    status = luaU_dump(L, clvalue(o)->l.p, writer, data, 0);
  else
    status = 1;
  lua_unlock(L);
  return status;
}


LUA_API int  lua_status (lua_State *L) {
  return L->status;
}


/*
** Garbage-collection function
*/

LUA_API int lua_gc (lua_State *L, int what, int data) {
  int res = 0;
  global_State *g;
  lua_lock(L);
  g = G(L);
  switch (what) {
    case LUA_GCSTOP: {
      g->GCthreshold = MAX_LUMEM;
      break;
    }
    case LUA_GCRESTART: {
      g->GCthreshold = g->totalbytes;
      break;
    }
    case LUA_GCCOLLECT: {
      luaC_fullgc(L);
      break;
    }
    case LUA_GCCOUNT: {
      /* GC values are expressed in Kbytes: #bytes/2^10 */
      res = cast_int(g->totalbytes >> 10);
      break;
    }
    case LUA_GCCOUNTB: {
      res = cast_int(g->totalbytes & 0x3ff);
      break;
    }
    case LUA_GCSTEP: {
      lu_mem a = (cast(lu_mem, data) << 10);
      if (a <= g->totalbytes)
        g->GCthreshold = g->totalbytes - a;
      else
        g->GCthreshold = 0;
      while (g->GCthreshold <= g->totalbytes) {
        luaC_step(L);
        if (g->gcstate == GCSpause) {  /* end of cycle? */
          res = 1;  /* signal it */
          break;
        }
      }
      break;
    }
    case LUA_GCSETPAUSE: {
      res = g->gcpause;
      g->gcpause = data;
      break;
    }
    case LUA_GCSETSTEPMUL: {
      res = g->gcstepmul;
      g->gcstepmul = data;
      break;
    }
    default: res = -1;  /* invalid option */
  }
  lua_unlock(L);
  return res;
}


/*
** miscellaneous functions
*/


LUA_API int lua_error (lua_State *L) {
  lua_lock(L);
  api_checknelems(L, 1);
  luaG_errormsg(L);
  lua_unlock(L);
  return 0;  /* to avoid warnings */
}


LUA_API int lua_next (lua_State *L, int idx) {
  StkId t;
  int more;
  lua_lock(L);
  t = index2adr(L, idx);
  api_check(L, ttistable(t));
  more = luaH_next(L, hvalue(t), L->top - 1);
  if (more) {
    api_incr_top(L);
  }
  else  /* no more elements */
    L->top -= 1;  /* remove key */
  lua_unlock(L);
  return more;
}


LUA_API void lua_concat (lua_State *L, int n) {
  lua_lock(L);
  api_checknelems(L, n);
  if (n >= 2) {
    luaC_checkGC(L);
    luaV_concat(L, n, cast_int(L->top - L->base) - 1);
    L->top -= (n-1);
  }
  else if (n == 0) {  /* push empty string */
    setsvalue2s(L, L->top, luaS_newlstr(L, "", 0));
    api_incr_top(L);
  }
  /* else n == 1; nothing to do */
  lua_unlock(L);
}


LUA_API lua_Alloc lua_getallocf (lua_State *L, void **ud) {
  lua_Alloc f;
  lua_lock(L);
  if (ud) *ud = G(L)->ud;
  f = G(L)->frealloc;
  lua_unlock(L);
  return f;
}


LUA_API void lua_setallocf (lua_State *L, lua_Alloc f, void *ud) {
  lua_lock(L);
  G(L)->ud = ud;
  G(L)->frealloc = f;
  lua_unlock(L);
}


LUA_API void *lua_newuserdata (lua_State *L, size_t size) {
  Udata *u;
  lua_lock(L);
  luaC_checkGC(L);
  u = luaS_newudata(L, size, getcurrenv(L));
  setuvalue(L, L->top, u);
  api_incr_top(L);
  lua_unlock(L);
  return u + 1;
}


static const char *aux_upvalue (StkId fi, int n, TValue **val) {
  Closure *f;
  if (!ttisfunction(fi)) return NULL;
  f = clvalue(fi);
  if (f->c.isC) {
    if (!(1 <= n && n <= f->c.nupvalues)) return NULL;
    *val = &f->c.upvalue[n-1];
    return "";
  }
  else {
    Proto *p = f->l.p;
    if (!(1 <= n && n <= p->sizeupvalues)) return NULL;
    *val = f->l.upvals[n-1]->v;
    return getstr(p->upvalues[n-1]);
  }
}


LUA_API const char *lua_getupvalue (lua_State *L, int funcindex, int n) {
  const char *name;
  TValue *val;
  lua_lock(L);
  name = aux_upvalue(index2adr(L, funcindex), n, &val);
  if (name) {
    setobj2s(L, L->top, val);
ofs	hex dump	ascii
0000	89 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52 00 00 00 10 00 00 00 10 08 06 00 00 00 1f f3 ff	.PNG........IHDR................
0020	61 00 00 03 00 50 4c 54 45 00 00 00 ff 00 00 00 ff 00 ff ff 00 00 00 ff ff 00 ff 00 ff ff ff ff	a....PLTE.......................
0040	ff db db db b6 b6 b6 92 92 92 6d 6d 6d 49 49 49 24 24 24 db 00 00 b6 00 00 92 00 00 6d 00 00 49	..........mmmIII$$$.........m..I
0060	00 00 24 00 00 00 db 00 00 b6 00 00 92 00 00 6d 00 00 49 00 00 24 00 db db 00 b6 b6 00 92 92 00	..$............m..I..$..........
0080	6d 6d 00 49 49 00 24 24 00 00 00 db 00 00 b6 00 00 92 00 00 6d 00 00 49 00 00 24 db 00 db b6 00	mm.II.$$............m..I..$.....
00a0	b6 92 00 92 6d 00 6d 49 00 49 24 00 24 00 db db 00 b6 b6 00 92 92 00 6d 6d 00 49 49 00 24 24 ff	....m.mI.I$.$..........mm.II.$$.
00c0	db db db b6 b6 b6 92 92 92 6d 6d 6d 49 49 49 24 24 ff b6 b6 db 92 92 b6 6d 6d 92 49 49 6d 24 24	.........mmmIII$$.......mm.IIm$$
00e0	ff 92 92 db 6d 6d b6 49 49 92 24 24 ff 6d 6d db 49 49 b6 24 24 ff 49 49 db 24 24 ff 24 24 db ff	....mm.II.$$.mm.II.$$.II.$$.$$..
0100	db b6 db b6 92 b6 92 6d 92 6d 49 6d 49 24 49 24 b6 ff b6 92 db 92 6d b6 6d 49 92 49 24 6d 24 92	.......m.mImI$I$......m.mI.I$m$.
0120	ff 92 6d db 6d 49 b6 49 24 92 24 6d ff 6d 49 db 49 24 b6 24 49 ff 49 24 db 24 24 ff 24 db db ff	..m.mI.I$.$m.mI.I$.$I.I$.$$.$...
0140	b6 b6 db 92 92 b6 6d 6d 92 49 49 6d 24 24 49 b6 b6 ff 92 92 db 6d 6d b6 49 49 92 24 24 6d 92 92	......mm.IIm$$I......mm.II.$$m..
0160	ff 6d 6d db 49 49 b6 24 24 92 6d 6d ff 49 49 db 24 24 b6 49 49 ff 24 24 db 24 24 ff ff ff db db	.mm.II.$$.mm.II.$$.II.$$.$$.....
0180	db b6 b6 b6 92 92 92 6d 6d 6d 49 49 49 24 ff ff b6 db db 92 b6 b6 6d 92 92 49 6d 6d 24 ff ff 92	.......mmmIII$........m..Imm$...
01a0	db db 6d b6 b6 49 92 92 24 ff ff 6d db db 49 b6 b6 24 ff ff 49 db db 24 ff ff 24 ff db ff db b6	..m..I..$..m..I..$..I..$..$.....
01c0	db b6 92 b6 92 6d 92 6d 49 6d 49 24 49 ff b6 ff db 92 db b6 6d b6 92 49 92 6d 24 6d ff 92 ff db	.....m.mImI$I.......m..I.m$m....
01e0	6d db b6 49 b6 92 24 92 ff 6d ff db 49 db b6 24 b6 ff 49 ff db 24 db ff 24 ff db ff ff b6 db db	m..I..$..m..I..$..I..$..$.......
0200	92 b6 b6 6d 92 92 49 6d 6d 24 49 49 b6 ff ff 92 db db 6d b6 b6 49 92 92 24 6d 6d 92 ff ff 6d db	...m..Imm$II......m..I..$mm...m.
0220	db 49 b6 b6 24 92 92 6d ff ff 49 db db 24 b6 b6 49 ff ff 24 db db 24 ff ff ff db b6 db b6 92 b6	.I..$..m..I..$..I..$..$.........
0240	92 6d 92 6d 49 6d 49 24 49 24 00 ff b6 92 db 92 6d b6 6d 49 92 49 24 6d 24 00 ff b6 db db 92 b6	.m.mImI$I$......m.mI.I$m$.......
0260	b6 6d 92 92 49 6d 6d 24 49 49 00 24 ff 92 b6 db 6d 92 b6 49 6d 92 24 49 6d 00 24 db b6 ff b6 92	.m..Imm$II.$....m..Im.$Im.$.....
0280	db 92 6d b6 6d 49 92 49 24 6d 24 00 49 b6 92 ff 92 6d db 6d 49 b6 49 24 92 24 00 6d b6 db ff 92	..m.mI.I$m$.I....m.mI.I$.$.m....
02a0	b6 db 6d 92 b6 49 6d 92 24 49 6d 00 24 49 92 b6 ff 6d 92 db 49 6d b6 24 49 92 00 24 6d b6 ff db	..m..Im.$Im.$I...m..Im.$I..$m...
02c0	92 db b6 6d b6 92 49 92 6d 24 6d 49 00 49 24 92 ff b6 6d db 92 49 b6 6d 24 92 49 00 6d 24 db ff	...m..I.m$mI.I$...m..I.m$.I.m$..
02e0	b6 b6 db 92 92 b6 6d 6d 92 49 49 6d 24 24 49 00 b6 ff 92 92 db 6d 6d b6 49 49 92 24 24 6d 00 ff	......mm.IIm$$I......mm.II.$$m..
0300	b6 00 db 92 00 b6 6d 00 92 49 00 ff 00 b6 db 00 92 b6 00 6d 92 00 49 00 b6 ff 00 92 db 00 6d b6	......m..I.........m..I.......m.
0320	00 49 92 00 00 00 00 00 00 cf 2a 02 04 00 00 00 73 49 44 41 54 38 cb cd 92 31 0e c0 20 0c 03 9d	.I........*.....sIDAT8...1......
0340	35 ef f0 9c ff bf 83 99 77 64 4d 27 24 a0 69 ab aa b4 aa 37 84 62 c8 d9 c0 6a 91 0c 92 f1 99 a9	5.......wdM'$.i....7.b...j......
0360	5c 0d aa 2a 4a 29 02 00 66 16 ee 0e 00 a8 b5 ca 60 d0 bf d0 2e ff a7 8c 45 ba c2 2c 55 1d ce 3d	\..*J)..f.......`.......E..,U..=
0380	87 dd ae 66 36 18 35 80 af 49 b2 ef cf 29 90 8c a3 64 e4 0c 58 c6 c0 dd d7 c6 fc b8 48 72 b7 07	...f6.5..I...)...d..X.......Hr..
03a0	cb db ba 01 5d 8e 39 8b 9c 03 e6 54 00 00 00 00 49 45 4e 44 ae 42 60 82	....].9....T....IEND.B`.