/*

 * 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)

{

    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.      */

  /* Return FALSE on failure.                                           */

  /* A size of 0 granules is used for large objects.                    */

  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;

  }

}