--- /dev/null
+/*
+** $Id: lgc.h,v 2.58.1.1 2013/04/12 18:48:47 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 GCSsweepstring 2
+#define GCSsweepudata 3
+#define GCSsweep 4
+#define GCSpause 5
+
+
+#define issweepphase(g) \
+ (GCSsweepstring <= (g)->gcstate && (g)->gcstate <= GCSsweep)
+
+#define isgenerational(g) ((g)->gckind == KGC_GEN)
+
+/*
+** macros to tell when main invariant (white objects cannot point to black
+** ones) must be kept. During a non-generational 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. During a generational collection, the
+** invariant must be kept all times.
+*/
+
+#define keepinvariant(g) (isgenerational(g) || g->gcstate <= GCSatomic)
+
+
+/*
+** Outside the collector, the state in generational mode is kept in
+** 'propagate', so 'keepinvariant' is always true.
+*/
+#define keepinvariantout(g) \
+ check_exp(g->gcstate == GCSpropagate || !isgenerational(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 separated for finalization */
+#define SEPARATED 4 /* object is in 'finobj' list or in 'tobefnz' */
+#define FIXEDBIT 5 /* object is fixed (should not be collected) */
+#define OLDBIT 6 /* object is old (only in generational mode) */
+/* bit 7 is currently used by tests (luaL_checkmemory) */
+
+#define WHITEBITS bit2mask(WHITE0BIT, WHITE1BIT)
+
+
+#define iswhite(x) testbits((x)->gch.marked, WHITEBITS)
+#define isblack(x) testbit((x)->gch.marked, BLACKBIT)
+#define isgray(x) /* neither white nor black */ \
+ (!testbits((x)->gch.marked, WHITEBITS | bitmask(BLACKBIT)))
+
+#define isold(x) testbit((x)->gch.marked, OLDBIT)
+
+/* MOVE OLD rule: whenever an object is moved to the beginning of
+ a GC list, its old bit must be cleared */
+#define resetoldbit(o) resetbit((o)->gch.marked, OLDBIT)
+
+#define otherwhite(g) (g->currentwhite ^ WHITEBITS)
+#define isdeadm(ow,m) (!(((m) ^ WHITEBITS) & (ow)))
+#define isdead(g,v) isdeadm(otherwhite(g), (v)->gch.marked)
+
+#define changewhite(x) ((x)->gch.marked ^= WHITEBITS)
+#define gray2black(x) l_setbit((x)->gch.marked, BLACKBIT)
+
+#define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x)))
+
+#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 (valiswhite(v) && isblack(obj2gco(p))) \
+ luaC_barrier_(L,obj2gco(p),gcvalue(v)); }
+
+#define luaC_barrierback(L,p,v) { if (valiswhite(v) && isblack(obj2gco(p))) \
+ luaC_barrierback_(L,p); }
+
+#define luaC_objbarrier(L,p,o) \
+ { if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) \
+ luaC_barrier_(L,obj2gco(p),obj2gco(o)); }
+
+#define luaC_objbarrierback(L,p,o) \
+ { if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) luaC_barrierback_(L,p); }
+
+#define luaC_barrierproto(L,p,c) \
+ { if (isblack(obj2gco(p))) luaC_barrierproto_(L,p,c); }
+
+LUAI_FUNC void luaC_freeallobjects (lua_State *L);
+LUAI_FUNC void luaC_step (lua_State *L);
+LUAI_FUNC void luaC_forcestep (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,
+ GCObject **list, int offset);
+LUAI_FUNC void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v);
+LUAI_FUNC void luaC_barrierback_ (lua_State *L, GCObject *o);
+LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c);
+LUAI_FUNC void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt);
+LUAI_FUNC void luaC_checkupvalcolor (global_State *g, UpVal *uv);
+LUAI_FUNC void luaC_changemode (lua_State *L, int mode);
+
+#endif
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