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/*

** $Id: lstate.h,v 2.68 2010/10/29 17:52:46 roberto Exp $

** Global State

** See Copyright Notice in lua.h

*/

#ifndef lstate_h

#define lstate_h

#include "lua.h"

#include "lobject.h"

#include "ltm.h"

#include "lzio.h"

/*

** Some notes about garbage-collected objects:  All objects in Lua must

** be kept somehow accessible until being freed.

**

** Lua keeps most objects linked in list g->allgc. The link uses field

** 'next' of the CommonHeader.

**

** Strings are kept in several lists headed by the array g->strt.hash.

**

** Open upvalues are not subject to independent garbage collection. They

** are collected together with their respective threads. Lua keeps a

** double-linked list with all open upvalues (g->uvhead) so that it can

** mark objects referred by them. (They are always gray, so they must

** be remarked in the atomic step. Usually their contents would be marked

** when traversing the respective threads, but the thread may already be

** dead, while the upvalue is still accessible through closures.)

**

** Userdata with finalizers are kept in the list g->udgc.

**

** The list g->tobefnz links all userdata being finalized.

*/

struct lua_longjmp;  /* defined in ldo.c */

/* extra stack space to handle TM calls and some other extras */

#define EXTRA_STACK   5

#define BASIC_CI_SIZE           8

#define BASIC_STACK_SIZE        (2*LUA_MINSTACK)

/* kinds of Garbage Collection */

#define KGC_NORMAL	0

#define KGC_EMERGENCY	1	/* gc was forced by an allocation failure */

#define KGC_GEN		2	/* generational collection */

typedef struct stringtable {

  GCObject **hash;

  lu_int32 nuse;  /* number of elements */

  int size;

} stringtable;

/*

** information about a call

*/

typedef struct CallInfo {

  StkId func;  /* function index in the stack */

  StkId	top;  /* top for this function */

  struct CallInfo *previous, *next;  /* dynamic call link */

  short nresults;  /* expected number of results from this function */

  lu_byte callstatus;

  union {

    struct {  /* only for Lua functions */

      StkId base;  /* base for this function */

      const Instruction *savedpc;

    } l;

    struct {  /* only for C functions */

      int ctx;  /* context info. in case of yields */

      lua_CFunction k;  /* continuation in case of yields */

      ptrdiff_t old_errfunc;

      ptrdiff_t extra;

      lu_byte old_allowhook;

      lu_byte status;

    } c;

  } u;

} CallInfo;

/*

** Bits in CallInfo status

*/

#define CIST_LUA	(1<<0)	/* call is running a Lua function */

#define CIST_HOOKED	(1<<1)	/* call is running a debug hook */

#define CIST_REENTRY	(1<<2)	/* call is running on same invocation of

                                   luaV_execute of previous call */

#define CIST_YIELDED	(1<<3)	/* call reentered after suspension */

#define CIST_YPCALL	(1<<4)	/* call is a yieldable protected call */

#define CIST_STAT	(1<<5)	/* call has an error status (pcall) */

#define CIST_TAIL	(1<<6)	/* call was tail called */

#define ci_func(ci)	(clvalue((ci)->func))

#define isLua(ci)	((ci)->callstatus & CIST_LUA)

/*

** `global state', shared by all threads of this state

*/

typedef struct global_State {

  lua_Alloc frealloc;  /* function to reallocate memory */

  void *ud;         /* auxiliary data to `frealloc' */

  lu_mem totalbytes;  /* number of bytes currently allocated */

  l_mem GCdebt;  /* when positive, run a GC step */

  lu_mem lastmajormem;  /* memory in use after last major collection */

  stringtable strt;  /* hash table for strings */

  TValue l_registry;

  unsigned short nCcalls;  /* number of nested C calls */

  lu_byte currentwhite;

  lu_byte gcstate;  /* state of garbage collector */

  lu_byte gckind;  /* kind of GC running */

  int sweepstrgc;  /* position of sweep in `strt' */

  GCObject *allgc;  /* list of all collectable objects */

  GCObject *udgc;  /* list of collectable userdata with finalizers */

  GCObject **sweepgc;  /* current position of sweep */

  GCObject *gray;  /* list of gray objects */

  GCObject *grayagain;  /* list of objects to be traversed atomically */

  GCObject *weak;  /* list of tables with weak values */

  GCObject *ephemeron;  /* list of ephemeron tables (weak keys) */

  GCObject *allweak;  /* list of all-weak tables */

  GCObject *tobefnz;  /* list of userdata to be GC */

  UpVal uvhead;  /* head of double-linked list of all open upvalues */

  Mbuffer buff;  /* temporary buffer for string concatenation */

  int gcpause;  /* size of pause between successive GCs */

  int gcmajorinc;  /* how much to wait for a major GC (only in gen. mode) */

  int gcstepmul;  /* GC `granularity' */

  lua_CFunction panic;  /* to be called in unprotected errors */

  struct lua_State *mainthread;

  const lua_Number *version;  /* pointer to version number */

  TString *memerrmsg;  /* memory-error message */

  TString *tmname[TM_N];  /* array with tag-method names */

  struct Table *mt[LUA_NUMTAGS];  /* metatables for basic types */

} global_State;

/*

** `per thread' state

*/

struct lua_State {

  CommonHeader;

  lu_byte status;

  StkId top;  /* first free slot in the stack */

  global_State *l_G;

  CallInfo *ci;  /* call info for current function */

  const Instruction *oldpc;  /* last pc traced */

  StkId stack_last;  /* last free slot in the stack */

  StkId stack;  /* stack base */

  int stacksize;

  unsigned short nny;  /* number of non-yieldable calls in stack */

  lu_byte hookmask;

  lu_byte allowhook;

  int basehookcount;

  int hookcount;

  lua_Hook hook;

  GCObject *openupval;  /* list of open upvalues in this stack */

  GCObject *gclist;

  struct lua_longjmp *errorJmp;  /* current error recover point */

  ptrdiff_t errfunc;  /* current error handling function (stack index) */

  CallInfo base_ci;  /* CallInfo for first level (C calling Lua) */

};

#define G(L)	(L->l_G)

/*

** Union of all collectable objects

*/

union GCObject {

  GCheader gch;  /* common header */

  union TString ts;

  union Udata u;

  union Closure cl;

  struct Table h;

  struct Proto p;

  struct UpVal uv;

  struct lua_State th;  /* thread */

};

#define gch(o)		(&(o)->gch)

/* macros to convert a GCObject into a specific value */

#define rawgco2ts(o)	check_exp((o)->gch.tt == LUA_TSTRING, &((o)->ts))

#define gco2ts(o)	(&rawgco2ts(o)->tsv)

#define rawgco2u(o)	check_exp((o)->gch.tt == LUA_TUSERDATA, &((o)->u))

#define gco2u(o)	(&rawgco2u(o)->uv)

#define gco2cl(o)	check_exp((o)->gch.tt == LUA_TFUNCTION, &((o)->cl))

#define gco2t(o)	check_exp((o)->gch.tt == LUA_TTABLE, &((o)->h))

#define gco2p(o)	check_exp((o)->gch.tt == LUA_TPROTO, &((o)->p))

#define gco2uv(o)	check_exp((o)->gch.tt == LUA_TUPVAL, &((o)->uv))

#define gco2th(o)	check_exp((o)->gch.tt == LUA_TTHREAD, &((o)->th))

/* macro to convert any Lua object into a GCObject */

#define obj2gco(v)	(cast(GCObject *, (v)))

LUAI_FUNC void luaE_freethread (lua_State *L, lua_State *L1);

LUAI_FUNC CallInfo *luaE_extendCI (lua_State *L);

LUAI_FUNC void luaE_freeCI (lua_State *L);

#endif