text: /*
  ** $Id: lstate.h,v 2.130 2015/12/16 16:39:38 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, so all objects always
  ** belong to one (and only one) of these lists, using field 'next' of
  ** the 'CommonHeader' for the link:
  **
  ** 'allgc': all objects not marked for finalization;
  ** 'finobj': all objects marked for finalization;
  ** 'tobefnz': all objects ready to be finalized; 
  ** 'fixedgc': all objects that are not to be collected (currently
  ** only small strings, such as reserved words).
  
  */
  
  
  struct lua_longjmp;  /* defined in ldo.c */
  
  
  /*
  ** Atomic type (relative to signals) to better ensure that 'lua_sethook' 
  ** is thread safe
  */
  #if !defined(l_signalT)
  #include <signal.h>
  #define l_signalT	sig_atomic_t
  #endif
  
  
  /* extra stack space to handle TM calls and some other extras */
  #define EXTRA_STACK   5
  
  
  #define BASIC_STACK_SIZE        (2*LUA_MINSTACK)
  
  #define INIT_STATE_ARRAY_SIZE   100
  
  
  /* kinds of Garbage Collection */
  #define KGC_NORMAL	0
  #define KGC_EMERGENCY	1	/* gc was forced by an allocation failure */
  
  
  typedef struct stringtable {
    TString **hash;
    int nuse;  /* number of elements */
    int size;
  } stringtable;
  
  
  /*
  ** Information about a call.
  ** When a thread yields, 'func' is adjusted to pretend that the
  ** top function has only the yielded values in its stack; in that
  ** case, the actual 'func' value is saved in field 'extra'. 
  ** When a function calls another with a continuation, 'extra' keeps
  ** the function index so that, in case of errors, the continuation
  ** function can be called with the correct top.
  */
  typedef struct CallInfo {
    StkId func;  /* function index in the stack */
    StkId	top;  /* top for this function */
    struct CallInfo *previous, *next;  /* dynamic call link */
    union {
      struct {  /* only for Lua functions */
        StkId base;  /* base for this function */
        const Instruction *savedpc;
      } l;
      struct {  /* only for C functions */
        lua_KFunction k;  /* continuation in case of yields */
        ptrdiff_t old_errfunc;
        lua_KContext ctx;  /* context info. in case of yields */
      } c;
    } u;
    ptrdiff_t extra;
    short nresults;  /* expected number of results from this function */
    lu_byte callstatus;
  } CallInfo;
  
  
  /*
  ** Bits in CallInfo status
  */
  #define CIST_OAH	(1<<0)	/* original value of 'allowhook' */
  #define CIST_LUA	(1<<1)	/* call is running a Lua function */
  #define CIST_HOOKED	(1<<2)	/* call is running a debug hook */
  #define CIST_FRESH	(1<<3)	/* call is running on a fresh invocation
                                     of luaV_execute */
  #define CIST_YPCALL	(1<<4)	/* call is a yieldable protected call */
  #define CIST_TAIL	(1<<5)	/* call was tail called */
  #define CIST_HOOKYIELD	(1<<6)	/* last hook called yielded */
  #define CIST_LEQ	(1<<7)  /* using __lt for __le */
  
  #define isLua(ci)	((ci)->callstatus & CIST_LUA)
  
  /* assume that CIST_OAH has offset 0 and that 'v' is strictly 0/1 */
  #define setoah(st,v)	((st) = ((st) & ~CIST_OAH) | (v))
  #define getoah(st)	((st) & CIST_OAH)
  
  
  /*
  ** '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' */
    l_mem totalbytes;  /* number of bytes currently allocated - GCdebt */
    l_mem GCdebt;  /* bytes allocated not yet compensated by the collector */
    lu_mem GCmemtrav;  /* memory traversed by the GC */
    lu_mem GCestimate;  /* an estimate of the non-garbage memory in use */
    stringtable strt;  /* hash table for strings */
    TValue l_registry;
    unsigned int seed;  /* randomized seed for hashes */
    lu_byte currentwhite;
    lu_byte gcstate;  /* state of garbage collector */
    lu_byte gckind;  /* kind of GC running */
    lu_byte gcrunning;  /* true if GC is running */
    GCObject *allgc;  /* list of all collectable objects */
    GCObject **sweepgc;  /* current position of sweep in list */
    GCObject *finobj;  /* list of collectable objects with finalizers */
    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 */
    GCObject *fixedgc;  /* list of objects not to be collected */
    struct lua_State *twups;  /* list of threads with open upvalues */
    unsigned int gcfinnum;  /* number of finalizers to call in each GC step */
    int gcpause;  /* size of pause between successive GCs */
    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 */
    TString *strcache[STRCACHE_N][STRCACHE_M];  /* cache for strings in API */
    struct lua_State **allstates; /* array of all states */
    struct lua_State *readystate; /* list of ready states */
    struct lua_State **plastreadystate;
    int statenum; /* length of state array */
    int statecount; /* number of states */
    int nextfreepid; /* next free position in allstates array */
  } global_State;
  
  
  /*
  ** 'per thread' state
  */
  struct lua_State {
    CommonHeader;
    unsigned short nci;  /* number of items in 'ci' list */
    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 */
    UpVal *openupval;  /* list of open upvalues in this stack */
    GCObject *gclist;
    struct lua_State *twups;  /* list of threads with open upvalues */
    struct lua_longjmp *errorJmp;  /* current error recover point */
    CallInfo base_ci;  /* CallInfo for first level (C calling Lua) */
    volatile lua_Hook hook;
    ptrdiff_t errfunc;  /* current error handling function (stack index) */
    struct lua_State *nextreadystate;
    int stacksize;
    int basehookcount;
    int hookcount;
    int pid; /* id of this process */
    int ppid; /* id of parent process */
    int nei; /* number of executed instructions in this tick */
    long total_nei; /* number of executed instructions from the thread beginning */
    unsigned short nny;  /* number of non-yieldable calls in stack */
    unsigned short nCcalls;  /* number of nested C calls */
    l_signalT hookmask;
    lu_byte allowhook;
  };
  
  
  #define G(L)	(L->l_G)
  
  
  /*
  ** Union of all collectable objects (only for conversions)
  */
  union GCUnion {
    GCObject gc;  /* common header */
    struct TString ts;
    struct Udata u;
    union Closure cl;
    struct Table h;
    struct Proto p;
    struct lua_State th;  /* thread */
  };
  
  
  #define cast_u(o)	cast(union GCUnion *, (o))
  
  /* macros to convert a GCObject into a specific value */
  #define gco2ts(o)  \
  	check_exp(novariant((o)->tt) == LUA_TSTRING, &((cast_u(o))->ts))
  #define gco2u(o)  check_exp((o)->tt == LUA_TUSERDATA, &((cast_u(o))->u))
  #define gco2lcl(o)  check_exp((o)->tt == LUA_TLCL, &((cast_u(o))->cl.l))
  #define gco2ccl(o)  check_exp((o)->tt == LUA_TCCL, &((cast_u(o))->cl.c))
  #define gco2cl(o)  \
  	check_exp(novariant((o)->tt) == LUA_TFUNCTION, &((cast_u(o))->cl))
  #define gco2t(o)  check_exp((o)->tt == LUA_TTABLE, &((cast_u(o))->h))
  #define gco2p(o)  check_exp((o)->tt == LUA_TPROTO, &((cast_u(o))->p))
  #define gco2th(o)  check_exp((o)->tt == LUA_TTHREAD, &((cast_u(o))->th))
  
  
  /* macro to convert a Lua object into a GCObject */
  #define obj2gco(v) \
  	check_exp(novariant((v)->tt) < LUA_TDEADKEY, (&(cast_u(v)->gc)))
  
  
  /* actual number of total bytes allocated */
  #define gettotalbytes(g)	cast(lu_mem, (g)->totalbytes + (g)->GCdebt)
  
  LUAI_FUNC void luaE_setdebt (global_State *g, l_mem debt);
  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);
  LUAI_FUNC void luaE_shrinkCI (lua_State *L);
  
  
  #endif
  
  