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 /* Return memory to the heap. */
19 void mfree(struct mdesc *mdp, void *ptr)
24 struct list *prev, *next;
32 if ((char *) ptr < (char *) mdp->heapbase || block > mdp->heapsize) {
33 printf("Ouch, this pointer is not mine. I refuse to free it.\n");
38 type = mdp->heapinfo[block].type;
40 THROWF(arg_error,0,"Asked to free a fragment in a block that is already free. I'm puzzled");
44 /* Find the free cluster previous to this one in the free list.
45 Start searching at the last block referenced; this may benefit
46 programs with locality of allocation. */
50 i = mdp->heapinfo[i].free_block.prev;
54 i = mdp->heapinfo[i].free_block.next;
56 while ((i != 0) && (i < block));
57 i = mdp->heapinfo[i].free_block.prev;
60 /* Determine how to link this block into the free list. */
61 if (block == i + mdp->heapinfo[i].free_block.size) {
63 /* Coalesce this block with its predecessor. */
64 mdp->heapinfo[i].free_block.size += mdp->heapinfo[block].busy_block.size;
65 /* Mark all my ex-blocks as free */
66 for (it=0; it<mdp->heapinfo[block].busy_block.size; it++)
67 mdp->heapinfo[block+it].type = -1;
71 //fprintf(stderr,"Free block %d to %d (as a new chunck)\n",block,block+mdp->heapinfo[block].busy_block.size);
72 /* Really link this block back into the free list. */
73 mdp->heapinfo[block].free_block.size = mdp->heapinfo[block].busy_block.size;
74 mdp->heapinfo[block].free_block.next = mdp->heapinfo[i].free_block.next;
75 mdp->heapinfo[block].free_block.prev = i;
76 mdp->heapinfo[i].free_block.next = block;
77 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
78 /* Mark all my ex-blocks as free */
79 for (it=0; it<mdp->heapinfo[block].free_block.size; it++)
80 mdp->heapinfo[block+it].type = -1;
83 /* Now that the block is linked in, see if we can coalesce it
84 with its successor (by deleting its successor from the list
85 and adding in its size). */
86 if (block + mdp->heapinfo[block].free_block.size ==
87 mdp->heapinfo[block].free_block.next) {
88 mdp->heapinfo[block].free_block.size
89 += mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.size;
90 mdp->heapinfo[block].free_block.next
91 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.next;
92 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
95 /* Now see if we can return stuff to the system. */
96 /* blocks = mdp -> heapinfo[block].free.size;
97 if (blocks >= FINAL_FREE_BLOCKS && block + blocks == mdp -> heaplimit
98 && mdp -> morecore (mdp, 0) == ADDRESS (block + blocks))
100 register size_t bytes = blocks * BLOCKSIZE;
101 mdp -> heaplimit -= blocks;
102 mdp -> morecore (mdp, -bytes);
103 mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
104 = mdp -> heapinfo[block].free.next;
105 mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
106 = mdp -> heapinfo[block].free.prev;
107 block = mdp -> heapinfo[block].free.prev;
108 mdp -> heapstats.chunks_free--;
109 mdp -> heapstats.bytes_free -= bytes;
112 /* Set the next search to begin at this block. */
113 mdp->heapindex = block;
117 /* Get the address of the first free fragment in this block. */
118 prev = (struct list *)
119 ((char *) ADDRESS(block) +
120 (mdp->heapinfo[block].busy_frag.first << type));
122 if (mdp->heapinfo[block].busy_frag.nfree ==
123 (BLOCKSIZE >> type) - 1) {
124 /* If all fragments of this block are free, remove them
125 from the fragment list and free the whole block. */
127 for (i = 1; i < (size_t) (BLOCKSIZE >> type); ++i) {
130 prev->prev->next = next;
132 next->prev = prev->prev;
134 /* pretend the block is used and free it so that it gets properly coalesced with adjacent free blocks */
135 mdp->heapinfo[block].type = 0;
136 mdp->heapinfo[block].busy_block.size = 1;
137 mdp->heapinfo[block].busy_block.busy_size = 0;
139 mfree((void *) mdp, (void *) ADDRESS(block));
140 } else if (mdp->heapinfo[block].busy_frag.nfree != 0) {
141 /* If some fragments of this block are free, link this
142 fragment into the fragment list after the first free
143 fragment of this block. */
144 next = (struct list *) ptr;
145 next->next = prev->next;
148 if (next->next != NULL) {
149 next->next->prev = next;
151 ++mdp->heapinfo[block].busy_frag.nfree;
153 /* No fragments of this block were free before the one we just released,
154 * so link this fragment into the fragment list and announce that
155 it is the first free fragment of this block. */
156 prev = (struct list *) ptr;
157 mdp->heapinfo[block].busy_frag.nfree = 1;
158 mdp->heapinfo[block].busy_frag.first =
159 RESIDUAL(ptr, BLOCKSIZE) >> type;
160 prev->next = mdp->fraghead[type].next;
161 prev->prev = &mdp->fraghead[type];
162 prev->prev->next = prev;
163 if (prev->next != NULL) {
164 prev->next->prev = prev;