/*

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

** Garbage Collector

** See Copyright Notice in lua.h

*/

#ifndef lgc_h

#define lgc_h

#include "lobject.h"

/*

** Possible states of the Garbage Collector

*/

#define GCSpause    0

#define GCSpropagate    1

#define GCSsweepstring  2

#define GCSsweep    3

#define GCSfinalize 4

/*

** some userful 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))

#define set2bits(x,b1,b2)   setbits(x, (bit2mask(b1, b2)))

#define reset2bits(x,b1,b2) resetbits(x, (bit2mask(b1, b2)))

#define test2bits(x,b1,b2)  testbits(x, (bit2mask(b1, b2)))

/*

** Layout for bit use in `marked' field:

** bit 0 - object is white (type 0)

** bit 1 - object is white (type 1)

** bit 2 - object is black

** bit 3 - for userdata: has been finalized

** bit 3 - for tables: has weak keys

** bit 4 - for tables: has weak values

** bit 5 - object is fixed (should not be collected)

** bit 6 - object is "super" fixed (only the main thread)

*/

#define WHITE0BIT   0

#define WHITE1BIT   1

#define BLACKBIT    2

#define FINALIZEDBIT    3

#define KEYWEAKBIT  3

#define VALUEWEAKBIT    4

#define FIXEDBIT    5

#define SFIXEDBIT   6

#define WHITEBITS   bit2mask(WHITE0BIT, WHITE1BIT)

#define iswhite(x)      test2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)

#define isblack(x)      testbit((x)->gch.marked, BLACKBIT)

#define isgray(x)   (!isblack(x) && !iswhite(x))

#define otherwhite(g)   (g->currentwhite ^ WHITEBITS)

#define isdead(g,v) ((v)->gch.marked & otherwhite(g) & WHITEBITS)

#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_checkGC(L) { \

  condhardstacktests(luaD_reallocstack(L, L->stacksize - EXTRA_STACK - 1)); \

  if (G(L)->totalbytes >= G(L)->GCthreshold) \

    luaC_step(L); }

#define luaC_barrier(L,p,v) { if (valiswhite(v) && isblack(obj2gco(p)))  \

    luaC_barrierf(L,obj2gco(p),gcvalue(v)); }

#define luaC_barriert(L,t,v) { if (valiswhite(v) && isblack(obj2gco(t)))  \

    luaC_barrierback(L,t); }

#define luaC_objbarrier(L,p,o)  \

    { if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) \

        luaC_barrierf(L,obj2gco(p),obj2gco(o)); }

#define luaC_objbarriert(L,t,o)  \

   { if (iswhite(obj2gco(o)) && isblack(obj2gco(t))) luaC_barrierback(L,t); }

LUAI_FUNC size_t luaC_separateudata (lua_State *L, int all);

LUAI_FUNC void luaC_callGCTM (lua_State *L);

LUAI_FUNC void luaC_freeall (lua_State *L);

LUAI_FUNC void luaC_step (lua_State *L);

LUAI_FUNC void luaC_fullgc (lua_State *L);

LUAI_FUNC void luaC_link (lua_State *L, GCObject *o, lu_byte tt);

LUAI_FUNC void luaC_linkupval (lua_State *L, UpVal *uv);

LUAI_FUNC void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v);

LUAI_FUNC void luaC_barrierback (lua_State *L, Table *t);

#endif