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;
28 if ((char *) ptr < (char *) mdp->heapbase || block > mdp->heapsize) {
29 printf("Ouch, this pointer is not mine. I refuse to free it.\n");
34 type = mdp->heapinfo[block].type;
36 THROWF(arg_error,0,"Asked to free a fragment in a block that is already free. I'm puzzled");
40 /* Find the free cluster previous to this one in the free list.
41 Start searching at the last block referenced; this may benefit
42 programs with locality of allocation. */
46 i = mdp->heapinfo[i].free_block.prev;
50 i = mdp->heapinfo[i].free_block.next;
52 while ((i != 0) && (i < block));
53 i = mdp->heapinfo[i].free_block.prev;
56 /* Determine how to link this block into the free list. */
57 if (block == i + mdp->heapinfo[i].free_block.size) {
59 /* Coalesce this block with its predecessor. */
60 mdp->heapinfo[i].free_block.size += mdp->heapinfo[block].busy_block.size;
61 /* Mark all my ex-blocks as free */
62 for (it=0; it<mdp->heapinfo[block].busy_block.size; it++)
63 mdp->heapinfo[block+it].type = -1;
67 //fprintf(stderr,"Free block %d to %d (as a new chunck)\n",block,block+mdp->heapinfo[block].busy_block.size);
68 /* Really link this block back into the free list. */
69 mdp->heapinfo[block].free_block.size = mdp->heapinfo[block].busy_block.size;
70 mdp->heapinfo[block].free_block.next = mdp->heapinfo[i].free_block.next;
71 mdp->heapinfo[block].free_block.prev = i;
72 mdp->heapinfo[i].free_block.next = block;
73 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
74 /* Mark all my ex-blocks as free */
75 for (it=0; it<mdp->heapinfo[block].free_block.size; it++)
76 mdp->heapinfo[block+it].type = -1;
79 /* Now that the block is linked in, see if we can coalesce it
80 with its successor (by deleting its successor from the list
81 and adding in its size). */
82 if (block + mdp->heapinfo[block].free_block.size ==
83 mdp->heapinfo[block].free_block.next) {
84 mdp->heapinfo[block].free_block.size
85 += mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.size;
86 mdp->heapinfo[block].free_block.next
87 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.next;
88 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
91 /* Now see if we can return stuff to the system. */
92 /* blocks = mdp -> heapinfo[block].free.size;
93 if (blocks >= FINAL_FREE_BLOCKS && block + blocks == mdp -> heaplimit
94 && mdp -> morecore (mdp, 0) == ADDRESS (block + blocks))
96 register size_t bytes = blocks * BLOCKSIZE;
97 mdp -> heaplimit -= blocks;
98 mdp -> morecore (mdp, -bytes);
99 mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
100 = mdp -> heapinfo[block].free.next;
101 mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
102 = mdp -> heapinfo[block].free.prev;
103 block = mdp -> heapinfo[block].free.prev;
104 mdp -> heapstats.chunks_free--;
105 mdp -> heapstats.bytes_free -= bytes;
108 /* Set the next search to begin at this block. */
109 mdp->heapindex = block;
113 /* Get the address of the first free fragment in this block. */
114 prev = (struct list *)
115 ((char *) ADDRESS(block) +
116 (mdp->heapinfo[block].busy_frag.first << type));
118 if (mdp->heapinfo[block].busy_frag.nfree ==
119 (BLOCKSIZE >> type) - 1) {
120 /* If all fragments of this block are free, remove them
121 from the fragment list and free the whole block. */
123 for (i = 1; i < (size_t) (BLOCKSIZE >> type); ++i) {
126 prev->prev->next = next;
128 next->prev = prev->prev;
130 /* pretend the block is used and free it so that it gets properly coalesced with adjacent free blocks */
131 mdp->heapinfo[block].type = 0;
132 mdp->heapinfo[block].busy_block.size = 1;
133 mdp->heapinfo[block].busy_block.busy_size = 0;
135 mfree((void *) mdp, (void *) ADDRESS(block));
136 } else if (mdp->heapinfo[block].busy_frag.nfree != 0) {
137 /* If some fragments of this block are free, link this
138 fragment into the fragment list after the first free
139 fragment of this block. */
140 next = (struct list *) ptr;
141 next->next = prev->next;
144 if (next->next != NULL) {
145 next->next->prev = next;
147 ++mdp->heapinfo[block].busy_frag.nfree;
149 /* No fragments of this block were free before the one we just released,
150 * so link this fragment into the fragment list and announce that
151 it is the first free fragment of this block. */
152 prev = (struct list *) ptr;
153 mdp->heapinfo[block].busy_frag.nfree = 1;
154 mdp->heapinfo[block].busy_frag.first =
155 RESIDUAL(ptr, BLOCKSIZE) >> type;
156 prev->next = mdp->fraghead[type].next;
157 prev->prev = &mdp->fraghead[type];
158 prev->prev->next = prev;
159 if (prev->next != NULL) {
160 prev->next->prev = prev;
167 /* Return memory to the heap. */
169 void mfree(xbt_mheap_t mdp, void *ptr)
172 __mmalloc_free(mdp, ptr);