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/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991, 1992 by Xerox Corporation. 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 copy this garbage collector for any purpose,
* provided the above notices are retained on all copies.
*/
/* 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.
*
* Boehm, February 6, 1992 1:00:09 pm PST
*/
# include "gc_private.h"
char * GC_invalid_map = 0;
/* Invalidate the object map associated with a block. Free blocks */
/* are identified by invalid maps. */
void GC_invalidate_map(hhdr)
hdr *hhdr;
{
register int displ;
if (GC_invalid_map == 0) {
GC_invalid_map = GC_scratch_alloc(MAP_SIZE);
for (displ = 0; displ < HBLKSIZE; displ++) {
MAP_ENTRY(GC_invalid_map, displ) = OBJ_INVALID;
}
}
hhdr -> hb_map = GC_invalid_map;
}
/* Consider pointers that are offset bytes displaced from the beginning */
/* of an object to be valid. */
void GC_register_displacement(offset)
word offset;
{
# ifndef ALL_INTERIOR_POINTERS
DCL_LOCK_STATE;
DISABLE_SIGNALS();
LOCK();
GC_register_displacement_inner(offset);
UNLOCK();
ENABLE_SIGNALS();
# endif
}
void GC_register_displacement_inner(offset)
word offset;
{
# ifndef ALL_INTERIOR_POINTERS
register int i;
if (offset > MAX_OFFSET) {
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;
for (i = 0; i <= MAXOBJSZ; i++) {
if (GC_obj_map[i] != 0) {
if (i == 0) {
GC_obj_map[i][offset + HDR_BYTES] = offset >> 2;
} else {
register int j;
register int lb = WORDS_TO_BYTES(i);
if (offset < lb) {
for (j = offset + HDR_BYTES; j < HBLKSIZE; j += lb) {
GC_obj_map[i][j] = offset >> 2;
}
}
}
}
}
}
# endif
}
/* Add a heap block map for objects of size sz to obj_map. */
void GC_add_map_entry(sz)
word sz;
{
register int obj_start;
register int displ;
register char * new_map;
if (sz > MAXOBJSZ) sz = 0;
if (GC_obj_map[sz] != 0) {
return;
}
new_map = GC_scratch_alloc(MAP_SIZE);
# ifdef PRINTSTATS
GC_printf("Adding block map for size %lu\n", (unsigned long)sz);
# endif
for (displ = 0; displ < HBLKSIZE; displ++) {
MAP_ENTRY(new_map,displ) = OBJ_INVALID;
}
if (sz == 0) {
for(displ = 0; displ <= MAX_OFFSET; displ++) {
if (OFFSET_VALID(displ)) {
MAP_ENTRY(new_map,displ+HDR_BYTES) = BYTES_TO_WORDS(displ);
}
}
} else {
for (obj_start = HDR_BYTES;
obj_start + WORDS_TO_BYTES(sz) <= HBLKSIZE;
obj_start += WORDS_TO_BYTES(sz)) {
for (displ = 0; displ < WORDS_TO_BYTES(sz); displ++) {
if (OFFSET_VALID(displ)) {
MAP_ENTRY(new_map, obj_start + displ) =
BYTES_TO_WORDS(displ);
}
}
}
}
GC_obj_map[sz] = new_map;
}
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