/* -----------------------------------------------------------------------------
- * $Id: Stable.h,v 1.1 1999/01/26 14:04:46 simonm Exp $
+ * $Id: Stable.h,v 1.8 2001/07/23 17:23:19 simonmar Exp $
*
- * Stable names and stable pointers
+ * (c) The GHC Team, 1998-2000
*
- * ---------------------------------------------------------------------------*/
+ * Stable Pointers: A stable pointer is represented as an index into
+ * the stable pointer table in the low BITS_PER_WORD-8 bits with a
+ * weight in the upper 8 bits.
+ *
+ * SUP: StgStablePtr used to be a synonym for StgWord, but stable pointers
+ * are guaranteed to be void* on the C-side, so we have to do some occasional
+ * casting. Size is not a matter, because StgWord is always the same size as
+ * a void*.
+ *
+ * ----------------------------------------------------------------------------*/
+
+#define STABLEPTR_WEIGHT_MASK ((StgWord)0xff << ((sizeof(StgWord)-1) * BITS_PER_BYTE))
+#define STABLEPTR_WEIGHT_SHIFT (BITS_IN(StgWord) - 8)
/* -----------------------------------------------------------------------------
External C Interface
extern StgStablePtr getStablePtr(StgPtr p);
typedef struct {
- StgPtr addr; /* either Haskell object or free list */
+ StgPtr addr; /* Haskell object, free list, or NULL */
+ StgPtr old; /* old Haskell object, used during GC */
StgWord weight; /* used for reference counting */
- unsigned int keep; /* set by the garbage collector */
+ StgClosure *sn_obj; /* the StableName object (or NULL) */
} snEntry;
-extern snEntry *stable_ptr_table;
-extern snEntry *stable_ptr_free;
+extern DLL_IMPORT_RTS snEntry *stable_ptr_table;
+extern DLL_IMPORT_RTS snEntry *stable_ptr_free;
-extern unsigned int SPT_size;
+extern DLL_IMPORT_RTS unsigned int SPT_size;
extern inline StgPtr
deRefStablePtr(StgStablePtr sp)
{
- ASSERT(stable_ptr_table[sp & ~STABLEPTR_WEIGHT_MASK].weight > 0);
- return stable_ptr_table[sp & ~STABLEPTR_WEIGHT_MASK].addr;
+ ASSERT(stable_ptr_table[stgCast(StgWord,sp) & ~STABLEPTR_WEIGHT_MASK].weight > 0);
+ return stable_ptr_table[stgCast(StgWord,sp) & ~STABLEPTR_WEIGHT_MASK].addr;
}
extern inline void
freeStablePtr(StgStablePtr sp)
{
- StgWord sn = sp & ~STABLEPTR_WEIGHT_MASK;
+ StgWord sn = stgCast(StgWord,sp) & ~STABLEPTR_WEIGHT_MASK;
ASSERT(sn < SPT_size
&& stable_ptr_table[sn].addr != NULL
&& stable_ptr_table[sn].weight > 0);
- stable_ptr_table[sn].weight += (sp & STABLEPTR_WEIGHT_MASK) >> STABLEPTR_WEIGHT_SHIFT;
+ stable_ptr_table[sn].weight +=
+ 1 << ((((StgWord)sp & STABLEPTR_WEIGHT_MASK) >> STABLEPTR_WEIGHT_SHIFT) - 1);
}
extern inline StgStablePtr
splitStablePtr(StgStablePtr sp)
{
/* doesn't need access to the stable pointer table */
- StgWord weight = (sp & STABLEPTR_WEIGHT_MASK) / 2;
- return (sp & ~STABLEPTR_WEIGHT_MASK) + weight;
+ StgWord weight = (stgCast(StgWord,sp) & STABLEPTR_WEIGHT_MASK) / 2;
+ return stgCast(StgStablePtr,(stgCast(StgWord,sp) & ~STABLEPTR_WEIGHT_MASK) + weight);
}
/* No deRefStableName, because the existence of a stable name doesn't