/*** $Id: lgc.h,v 2.86 2014/10/25 11:50:46 roberto Exp $** Garbage Collector** See Copyright Notice in lua.h*/ #ifndef lgc_h#define lgc_h  #include "lobject.h"#include "lstate.h" /*** Collectable objects may have one of three colors: white, which** means the object is not marked; gray, which means the** object is marked, but its references may be not marked; and** black, which means that the object and all its references are marked.** The main invariant of the garbage collector, while marking objects,** is that a black object can never point to a white one. Moreover,** any gray object must be in a "gray list" (gray, grayagain, weak,** allweak, ephemeron) so that it can be visited again before finishing** the collection cycle. These lists have no meaning when the invariant** is not being enforced (e.g., sweep phase).*/   /* how much to allocate before next GC step */#if !defined(GCSTEPSIZE)/* ~100 small strings */#define GCSTEPSIZE	(cast_int(100 * sizeof(TString)))#endif  /*** Possible states of the Garbage Collector*/#define GCSpropagate	0#define GCSatomic	1#define GCSswpallgc	2#define GCSswpfinobj	3#define GCSswptobefnz	4#define GCSswpend	5#define GCScallfin	6#define GCSpause	7  #define issweepphase(g)  \	(GCSswpallgc <= (g)->gcstate && (g)->gcstate <= GCSswpend)  /*** macro to tell when main invariant (white objects cannot point to black** ones) must be kept. During a collection, the sweep** phase may break the invariant, as objects turned white may point to** still-black objects. The invariant is restored when sweep ends and** all objects are white again.*/ #define keepinvariant(g)	((g)->gcstate <= GCSatomic)  /*** some useful bit tricks*/#define resetbits(x,m)		((x) &= cast(lu_byte, ~(m)))#define setbits(x,m)		((x) |= (m))#define testbits(x,m)		((x) & (m))#define bitmask(b)		(1<<(b))#define bit2mask(b1,b2)		(bitmask(b1) | bitmask(b2))#define l_setbit(x,b)		setbits(x, bitmask(b))#define resetbit(x,b)		resetbits(x, bitmask(b))#define testbit(x,b)		testbits(x, bitmask(b))  /* Layout for bit use in 'marked' field: */#define WHITE0BIT	0  /* object is white (type 0) */#define WHITE1BIT	1  /* object is white (type 1) */#define BLACKBIT	2  /* object is black */#define FINALIZEDBIT	3  /* object has been marked for finalization *//* bit 7 is currently used by tests (luaL_checkmemory) */ #define WHITEBITS	bit2mask(WHITE0BIT, WHITE1BIT)  #define iswhite(x)      testbits((x)->marked, WHITEBITS)#define isblack(x)      testbit((x)->marked, BLACKBIT)#define isgray(x)  /* neither white nor black */  \	(!testbits((x)->marked, WHITEBITS | bitmask(BLACKBIT))) #define tofinalize(x)	testbit((x)->marked, FINALIZEDBIT) #define otherwhite(g)	((g)->currentwhite ^ WHITEBITS)#define isdeadm(ow,m)	(!(((m) ^ WHITEBITS) & (ow)))#define isdead(g,v)	isdeadm(otherwhite(g), (v)->marked) #define changewhite(x)	((x)->marked ^= WHITEBITS)#define gray2black(x)	l_setbit((x)->marked, BLACKBIT) #define luaC_white(g)	cast(lu_byte, (g)->currentwhite & WHITEBITS)  #define luaC_condGC(L,c) \	{if (G(L)->GCdebt > 0) {c;}; condchangemem(L);}#define luaC_checkGC(L)		luaC_condGC(L, luaC_step(L);)  #define luaC_barrier(L,p,v) {  \	if (iscollectable(v) && isblack(p) && iswhite(gcvalue(v)))  \	luaC_barrier_(L,obj2gco(p),gcvalue(v)); } #define luaC_barrierback(L,p,v) {  \	if (iscollectable(v) && isblack(p) && iswhite(gcvalue(v)))  \	luaC_barrierback_(L,p); } #define luaC_objbarrier(L,p,o) {  \	if (isblack(p) && iswhite(o)) \		luaC_barrier_(L,obj2gco(p),obj2gco(o)); } #define luaC_upvalbarrier(L,uv) \  { if (iscollectable((uv)->v) && !upisopen(uv)) \         luaC_upvalbarrier_(L,uv); } LUAI_FUNC void luaC_fix (lua_State *L, GCObject *o);LUAI_FUNC void luaC_freeallobjects (lua_State *L);LUAI_FUNC void luaC_step (lua_State *L);LUAI_FUNC void luaC_runtilstate (lua_State *L, int statesmask);LUAI_FUNC void luaC_fullgc (lua_State *L, int isemergency);LUAI_FUNC GCObject *luaC_newobj (lua_State *L, int tt, size_t sz);LUAI_FUNC void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v);LUAI_FUNC void luaC_barrierback_ (lua_State *L, Table *o);LUAI_FUNC void luaC_upvalbarrier_ (lua_State *L, UpVal *uv);LUAI_FUNC void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt);LUAI_FUNC void luaC_upvdeccount (lua_State *L, UpVal *uv);  #endif