1 /*
2 ** $Id$
3 ** Garbage Collector
4 ** See Copyright Notice in lua.h
5 */
6 
7 #ifndef lgc_h
8 #define lgc_h
9 
10 
11 #include "lobject.h"
12 
13 
14 /*
15 ** Possible states of the Garbage Collector
16 */
17 #define GCSpause	0
18 #define GCSpropagate	1
19 #define GCSsweepstring	2
20 #define GCSsweep	3
21 #define GCSfinalize	4
22 
23 
24 /*
25 ** some userful bit tricks
26 */
27 #define resetbits(x,m)	((x) &= cast(lu_byte, ~(m)))
28 #define setbits(x,m)	((x) |= (m))
29 #define testbits(x,m)	((x) & (m))
30 #define bitmask(b)	(1<<(b))
31 #define bit2mask(b1,b2)	(bitmask(b1) | bitmask(b2))
32 #define l_setbit(x,b)	setbits(x, bitmask(b))
33 #define resetbit(x,b)	resetbits(x, bitmask(b))
34 #define testbit(x,b)	testbits(x, bitmask(b))
35 #define set2bits(x,b1,b2)	setbits(x, (bit2mask(b1, b2)))
36 #define reset2bits(x,b1,b2)	resetbits(x, (bit2mask(b1, b2)))
37 #define test2bits(x,b1,b2)	testbits(x, (bit2mask(b1, b2)))
38 
39 
40 
41 /*
42 ** Layout for bit use in `marked' field:
43 ** bit 0 - object is white (type 0)
44 ** bit 1 - object is white (type 1)
45 ** bit 2 - object is black
46 ** bit 3 - for userdata: has been finalized
47 ** bit 3 - for tables: has weak keys
48 ** bit 4 - for tables: has weak values
49 ** bit 5 - object is fixed (should not be collected)
50 ** bit 6 - object is "super" fixed (only the main thread)
51 */
52 
53 
54 #define WHITE0BIT	0
55 #define WHITE1BIT	1
56 #define BLACKBIT	2
57 #define FINALIZEDBIT	3
58 #define KEYWEAKBIT	3
59 #define VALUEWEAKBIT	4
60 #define FIXEDBIT	5
61 #define SFIXEDBIT	6
62 #define WHITEBITS	bit2mask(WHITE0BIT, WHITE1BIT)
63 
64 
65 #define iswhite(x)      test2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
66 #define isblack(x)      testbit((x)->gch.marked, BLACKBIT)
67 #define isgray(x)	(!isblack(x) && !iswhite(x))
68 
69 #define otherwhite(g)	(g->currentwhite ^ WHITEBITS)
70 #define isdead(g,v)	((v)->gch.marked & otherwhite(g) & WHITEBITS)
71 
72 #define changewhite(x)	((x)->gch.marked ^= WHITEBITS)
73 #define gray2black(x)	l_setbit((x)->gch.marked, BLACKBIT)
74 
75 #define valiswhite(x)	(iscollectable(x) && iswhite(gcvalue(x)))
76 
77 #define luaC_white(g)	cast(lu_byte, (g)->currentwhite & WHITEBITS)
78 
79 
80 #define luaC_checkGC(L) { \
81   condhardstacktests(luaD_reallocstack(L, L->stacksize - EXTRA_STACK - 1)); \
82   if (G(L)->totalbytes >= G(L)->GCthreshold) \
83 	luaC_step(L); }
84 
85 
86 #define luaC_barrier(L,p,v) { if (valiswhite(v) && isblack(obj2gco(p)))  \
87 	luaC_barrierf(L,obj2gco(p),gcvalue(v)); }
88 
89 #define luaC_barriert(L,t,v) { if (valiswhite(v) && isblack(obj2gco(t)))  \
90 	luaC_barrierback(L,t); }
91 
92 #define luaC_objbarrier(L,p,o)  \
93 	{ if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) \
94 		luaC_barrierf(L,obj2gco(p),obj2gco(o)); }
95 
96 #define luaC_objbarriert(L,t,o)  \
97    { if (iswhite(obj2gco(o)) && isblack(obj2gco(t))) luaC_barrierback(L,t); }
98 
99 LUAI_FUNC size_t luaC_separateudata (lua_State *L, int all);
100 LUAI_FUNC void luaC_callGCTM (lua_State *L);
101 LUAI_FUNC void luaC_freeall (lua_State *L);
102 LUAI_FUNC void luaC_step (lua_State *L);
103 LUAI_FUNC void luaC_fullgc (lua_State *L);
104 LUAI_FUNC void luaC_link (lua_State *L, GCObject *o, lu_byte tt);
105 LUAI_FUNC void luaC_linkupval (lua_State *L, UpVal *uv);
106 LUAI_FUNC void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v);
107 LUAI_FUNC void luaC_barrierback (lua_State *L, Table *t);
108 
109 
110 #endif
111