cleaner code for manipulation of `marked' field

lgc.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.h,v 1.20 2003/07/16 20:49:02 roberto Exp roberto $
+** $Id: lgc.h,v 1.21 2003/07/29 19:25:37 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -11,6 +11,35 @@
 #include "lobject.h"
 
 
+/*
+ * ** some userful bit tricks
+ * */
+#define bitmask(b)	(1<<(b))
+#define setbit(x,b)	((x) |= bitmask(b))
+#define resetbit(x,b)	((x) &= cast(lu_byte, ~bitmask(b)))
+#define testbit(x,b)	((x) & bitmask(b))
+
+
+
+/*
+** Layout for bit use in `marked' field:
+** bit 0 - object is white (not used yet)
+** 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 - for strings: is fixed (should not be collected)
+*/
+
+#define WHITEBIT	0
+#define BLACKBIT	1
+#define FINALIZEDBIT	2
+#define KEYWEAKBIT	2
+#define VALUEWEAKBIT	3
+#define FIXEDBIT	4
+
+
+
 #define luaC_checkGC(L) { if (G(L)->nblocks >= G(L)->GCthreshold) \
 	luaC_collectgarbage(L); }