/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991, 1992 by Xerox Corporation.  All rights reserved.
* Copyright (c) 1999-2001 by Hewlett-Packard Company. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose,  provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/

#include "private/gc_priv.h"

/* Routines for maintaining maps describing heap block
* layouts for various object sizes.  Allows fast pointer validity checks
* and fast location of object start locations on machines (such as SPARC)
* with slow division.
*/

/* Consider pointers that are offset bytes displaced from the beginning */
/* of an object to be valid.                                            */

GC_API void GC_CALL GC_register_displacement(size_t offset)
{
   DCL_LOCK_STATE;

   LOCK();
   GC_register_displacement_inner(offset);
   UNLOCK();
}

GC_INNER void GC_register_displacement_inner(size_t offset)
{
   GC_ASSERT(I_HOLD_LOCK());
   if (offset >= VALID_OFFSET_SZ) {
       ABORT("Bad argument to GC_register_displacement");
   }
   if (!GC_valid_offsets[offset]) {
     GC_valid_offsets[offset] = TRUE;
     GC_modws_valid_offsets[offset % sizeof(word)] = TRUE;
   }
}

#ifdef MARK_BIT_PER_GRANULE
 /* Add a heap block map for objects of size granules to obj_map.      */
 /* A size of 0 is used for large objects.  Return FALSE on failure.   */
 GC_INNER GC_bool GC_add_map_entry(size_t granules)
 {
   unsigned displ;
   unsigned short * new_map;

   if (granules > BYTES_TO_GRANULES(MAXOBJBYTES)) granules = 0;
   if (GC_obj_map[granules] != 0) {
       return(TRUE);
   }
   new_map = (unsigned short *)GC_scratch_alloc(MAP_LEN * sizeof(short));
   if (new_map == 0) return(FALSE);
   GC_COND_LOG_PRINTF(
               "Adding block map for size of %u granules (%u bytes)\n",
               (unsigned)granules, (unsigned)GRANULES_TO_BYTES(granules));
   if (granules == 0) {
     for (displ = 0; displ < BYTES_TO_GRANULES(HBLKSIZE); displ++) {
       new_map[displ] = 1;  /* Nonzero to get us out of marker fast path. */
     }
   } else {
     for (displ = 0; displ < BYTES_TO_GRANULES(HBLKSIZE); displ++) {
       new_map[displ] = (unsigned short)(displ % granules);
     }
   }
   GC_obj_map[granules] = new_map;
   return(TRUE);
 }
#endif /* MARK_BIT_PER_GRANULE */

GC_INNER void GC_initialize_offsets(void)
{
 unsigned i;
 if (GC_all_interior_pointers) {
   for (i = 0; i < VALID_OFFSET_SZ; ++i)
     GC_valid_offsets[i] = TRUE;
 } else {
   BZERO(GC_valid_offsets, sizeof(GC_valid_offsets));
   for (i = 0; i < sizeof(word); ++i)
     GC_modws_valid_offsets[i] = FALSE;
 }
}