1 /* Free a block of memory allocated by `mmalloc'.
2 Copyright 1990, 1991, 1992 Free Software Foundation
4 Written May 1989 by Mike Haertel.
5 Heavily modified Mar 1992 by Fred Fish. (fnf@cygnus.com) */
7 /* Copyright (c) 2010. The SimGrid Team.
8 * All rights reserved. */
10 /* This program is free software; you can redistribute it and/or modify it
11 * under the terms of the license (GNU LGPL) which comes with this package. */
13 #include "mmprivate.h"
15 /* Return memory to the heap.
16 Like `mfree' but don't call a mfree_hook if there is one. */
18 void __mmalloc_free(struct mdesc *mdp, void *ptr)
23 struct list *prev, *next;
27 if ((char *) ptr < (char *) mdp->heapbase || block > mdp->heapsize) {
28 printf("Ouch, this pointer is not mine. I refuse to free it.\n");
33 type = mdp->heapinfo[block].type;
35 THROWF(arg_error,0,"Asked to free a fragment in a block that is already free. I'm puzzled");
39 /* Find the free cluster previous to this one in the free list.
40 Start searching at the last block referenced; this may benefit
41 programs with locality of allocation. */
45 i = mdp->heapinfo[i].free_block.prev;
49 i = mdp->heapinfo[i].free_block.next;
51 while ((i != 0) && (i < block));
52 i = mdp->heapinfo[i].free_block.prev;
55 /* Determine how to link this block into the free list. */
56 if (block == i + mdp->heapinfo[i].free_block.size) {
57 /* Coalesce this block with its predecessor. */
58 mdp->heapinfo[i].free_block.size += mdp->heapinfo[block].busy_block.size;
61 /* Really link this block back into the free list. */
62 mdp->heapinfo[block].free_block.size = mdp->heapinfo[block].busy_block.size;
63 mdp->heapinfo[block].free_block.next = mdp->heapinfo[i].free_block.next;
64 mdp->heapinfo[block].free_block.prev = i;
65 mdp->heapinfo[i].free_block.next = block;
66 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
69 /* Now that the block is linked in, see if we can coalesce it
70 with its successor (by deleting its successor from the list
71 and adding in its size). */
72 if (block + mdp->heapinfo[block].free_block.size ==
73 mdp->heapinfo[block].free_block.next) {
74 mdp->heapinfo[block].free_block.size
75 += mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.size;
76 mdp->heapinfo[block].free_block.next
77 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.next;
78 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
81 /* Now see if we can return stuff to the system. */
82 /* blocks = mdp -> heapinfo[block].free.size;
83 if (blocks >= FINAL_FREE_BLOCKS && block + blocks == mdp -> heaplimit
84 && mdp -> morecore (mdp, 0) == ADDRESS (block + blocks))
86 register size_t bytes = blocks * BLOCKSIZE;
87 mdp -> heaplimit -= blocks;
88 mdp -> morecore (mdp, -bytes);
89 mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
90 = mdp -> heapinfo[block].free.next;
91 mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
92 = mdp -> heapinfo[block].free.prev;
93 block = mdp -> heapinfo[block].free.prev;
94 mdp -> heapstats.chunks_free--;
95 mdp -> heapstats.bytes_free -= bytes;
98 /* Set the next search to begin at this block. */
99 mdp->heapindex = block;
103 /* Get the address of the first free fragment in this block. */
104 prev = (struct list *)
105 ((char *) ADDRESS(block) +
106 (mdp->heapinfo[block].busy_frag.first << type));
108 if (mdp->heapinfo[block].busy_frag.nfree ==
109 (BLOCKSIZE >> type) - 1) {
110 /* If all fragments of this block are free, remove them
111 from the fragment list and free the whole block. */
113 for (i = 1; i < (size_t) (BLOCKSIZE >> type); ++i) {
116 prev->prev->next = next;
118 next->prev = prev->prev;
120 mdp->heapinfo[block].type = 0;
121 mdp->heapinfo[block].busy_block.size = 1;
122 mdp->heapinfo[block].busy_block.busy_size = 0;
124 mfree((void *) mdp, (void *) ADDRESS(block));
125 } else if (mdp->heapinfo[block].busy_frag.nfree != 0) {
126 /* If some fragments of this block are free, link this
127 fragment into the fragment list after the first free
128 fragment of this block. */
129 next = (struct list *) ptr;
130 next->next = prev->next;
133 if (next->next != NULL) {
134 next->next->prev = next;
136 ++mdp->heapinfo[block].busy_frag.nfree;
138 /* No fragments of this block are free, so link this
139 fragment into the fragment list and announce that
140 it is the first free fragment of this block. */
141 prev = (struct list *) ptr;
142 mdp->heapinfo[block].busy_frag.nfree = 1;
143 mdp->heapinfo[block].busy_frag.first =
144 RESIDUAL(ptr, BLOCKSIZE) >> type;
145 prev->next = mdp->fraghead[type].next;
146 prev->prev = &mdp->fraghead[type];
147 prev->prev->next = prev;
148 if (prev->next != NULL) {
149 prev->next->prev = prev;
156 /* Return memory to the heap. */
158 void mfree(xbt_mheap_t mdp, void *ptr)
161 __mmalloc_free(mdp, ptr);