1 /* Change the size of a block allocated by `mmalloc'.
2 Copyright 1990, 1991 Free Software Foundation
3 Written May 1989 by Mike Haertel. */
5 /* Copyright (c) 2010. The SimGrid Team.
6 * All rights reserved. */
8 /* This program is free software; you can redistribute it and/or modify it
9 * under the terms of the license (GNU LGPL) which comes with this package. */
11 #include <string.h> /* Prototypes for memcpy, memmove, memset, etc */
12 #include <stdlib.h> /* abort */
14 #include "mmprivate.h"
16 /* Resize the given region to the new size, returning a pointer
17 to the (possibly moved) region. This is optimized for speed;
18 some benchmarks seem to indicate that greater compactness is
19 achieved by unconditionally allocating and copying to a
20 new region. This module has incestuous knowledge of the
21 internals of both mfree and mmalloc. */
23 void *mrealloc(xbt_mheap_t mdp, void *ptr, size_t size)
27 size_t block, blocks, oldlimit;
29 /* Only keep real realloc, and reroute hidden malloc and free to the relevant functions */
32 return mmalloc(mdp, 0);
33 } else if (ptr == NULL) {
34 return mmalloc(mdp, size);
37 //printf("(%s)realloc %p to %d...",xbt_thread_self_name(),ptr,(int)size);
39 if ((char *) ptr < (char *) mdp->heapbase || BLOCK(ptr) > mdp->heapsize) {
41 ("FIXME. Ouch, this pointer is not mine, refusing to proceed (another solution would be to malloc it instead of reallocing it, see source code)\n");
42 result = mmalloc(mdp, size);
49 type = mdp->heapinfo[block].type;
53 fprintf(stderr, "Asked realloc a fragment comming from a *free* block. I'm puzzled.\n");
58 /* Maybe reallocate a large block to a small fragment. */
60 if (size <= BLOCKSIZE / 2) { // Full block -> Fragment; no need to optimize for time
62 result = mmalloc(mdp, size);
63 if (result != NULL) { // useless (mmalloc never returns NULL), but harmless
64 memcpy(result, ptr, size);
70 /* The new size is a large allocation as well;
71 see if we can hold it in place. */
72 blocks = BLOCKIFY(size);
73 if (blocks < mdp->heapinfo[block].busy_block.size) {
75 /* The new size is smaller; return excess memory to the free list. */
76 //printf("(%s) return excess memory...",xbt_thread_self_name());
77 for (it= block+blocks; it< mdp->heapinfo[block].busy_block.size ; it++)
78 mdp->heapinfo[it].type = 0;
79 mdp->heapinfo[block + blocks].busy_block.size
80 = mdp->heapinfo[block].busy_block.size - blocks;
81 mdp->heapinfo[block].busy_block.size = blocks;
82 mdp->heapinfo[block].busy_block.busy_size = size;
84 mfree(mdp, ADDRESS(block + blocks));
86 } else if (blocks == mdp->heapinfo[block].busy_block.size) {
87 /* No size change necessary. */
90 /* Won't fit, so allocate a new region that will.
91 Free the old region first in case there is sufficient
92 adjacent free space to grow without moving. */
93 blocks = mdp->heapinfo[block].busy_block.size;
94 /* Prevent free from actually returning memory to the system. */
95 oldlimit = mdp->heaplimit;
98 mdp->heaplimit = oldlimit;
99 result = mmalloc(mdp, size);
100 if (result == NULL) {
101 mmalloc(mdp, blocks * BLOCKSIZE);
105 memmove(result, ptr, blocks * BLOCKSIZE);
110 /* Old size is a fragment; type is logarithm
111 to base two of the fragment size. */
112 if (size > (size_t) (1 << (type - 1)) && size <= (size_t) (1 << type)) {
113 /* The new size is the same kind of fragment. */
114 //printf("(%s) new size is same kind of fragment...",xbt_thread_self_name());
117 /* The new size is different; allocate a new space,
118 and copy the lesser of the new size and the old. */
119 //printf("(%s) new size is different...",xbt_thread_self_name());
121 result = mmalloc(mdp, size);
125 memcpy(result, ptr, MIN(size, (size_t) 1 << type));
130 //printf("(%s) Done reallocing: %p\n",xbt_thread_self_name(),result);fflush(stdout);