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/*
** $Id: lgc.h,v 2.2 2003/12/12 18:29:34 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
#ifndef lgc_h
#define lgc_h
#include "lobject.h"
/*
** Possible states of the Garbage Collector
*/
#define GCSpropagate 0
#define GCSsweepstring 1
#define GCSsweep 2
#define GCSfinalize 3
/*
** 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 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 gray
** bit 1 - object is black
** bit 2 - For userdata: is finalized;
for tables: has weak keys
** bit 3 - for tables: has weak values
** bit 4 - object is fixed (should not be collected)
*/
#define WHITE0BIT 0
#define WHITE1BIT 1
#define BLACKBIT 2
#define FINALIZEDBIT 3
#define KEYWEAKBIT 3
#define VALUEWEAKBIT 4
#define FIXEDBIT 5
#define iswhite(x) test2bits((x)->gch.marked, WHITE0BIT, WHITE1BIT)
#define isblack(x) testbit((x)->gch.marked, BLACKBIT)
#define otherwhite(g) (g->currentwhite ^ bit2mask(WHITE0BIT, WHITE1BIT))
#define isdead(g,v) ((v)->gch.marked & otherwhite(g))
#define changewhite(x) ((x)->gch.marked ^= bit2mask(WHITE0BIT, WHITE1BIT))
#define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x)))
#define luaC_white(g) cast(lu_byte, (g)->currentwhite)
#define luaC_checkGC(L) { if (G(L)->nblocks >= 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_objbarrier(L,p,o) \
{ if (iswhite(obj2gco(o)) && isblack(obj2gco(p))) \
luaC_barrierf(L,obj2gco(p),obj2gco(o)); }
size_t luaC_separateudata (lua_State *L, int all);
void luaC_callGCTM (lua_State *L);
void luaC_sweepall (lua_State *L);
void luaC_step (lua_State *L);
void luaC_link (lua_State *L, GCObject *o, lu_byte tt);
void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v);
#endif
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