1 /*

     2 ** $Id: lgc.h,v 2.15.1.1 2007/12/27 13:02:25 roberto Exp $

     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