lgc.h

   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