1 /* Memory allocator `malloc'.
2 Copyright 1990, 1991, 1992 Free Software Foundation
4 Written May 1989 by Mike Haertel.
5 Heavily modified Mar 1992 by Fred Fish for mmap'd version. */
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 <string.h> /* Prototypes for memcpy, memmove, memset, etc */
15 #include "mmprivate.h"
17 /* Prototypes for local functions */
19 static int initialize(struct mdesc *mdp);
20 static void *morecore(struct mdesc *mdp, size_t size);
21 static void *align(struct mdesc *mdp, size_t size);
23 /* Aligned allocation. */
25 static void *align(struct mdesc *mdp, size_t size)
28 unsigned long int adj;
30 result = mmorecore(mdp, size);
31 adj = RESIDUAL(result, BLOCKSIZE);
33 adj = BLOCKSIZE - adj;
35 result = (char *) result + adj;
40 /* Set everything up and remember that we have. */
42 static int initialize(struct mdesc *mdp)
44 mdp->heapsize = HEAP / BLOCKSIZE;
45 mdp->heapinfo = (malloc_info *)
46 align(mdp, mdp->heapsize * sizeof(malloc_info));
47 if (mdp->heapinfo == NULL) {
50 memset((void *) mdp->heapinfo, 0, mdp->heapsize * sizeof(malloc_info));
51 mdp->heapinfo[0].free.size = 0;
52 mdp->heapinfo[0].free.next = mdp->heapinfo[0].free.prev = 0;
54 mdp->heapbase = (void *) mdp->heapinfo;
55 mdp->flags |= MMALLOC_INITIALIZED;
59 /* Get neatly aligned memory, initializing or
60 growing the heap info table as necessary. */
62 static void *morecore(struct mdesc *mdp, size_t size)
65 malloc_info *newinfo, *oldinfo;
68 result = align(mdp, size);
73 /* Check if we need to grow the info table. */
74 if ((size_t) BLOCK((char *) result + size) > mdp->heapsize) {
75 newsize = mdp->heapsize;
76 while ((size_t) BLOCK((char *) result + size) > newsize) {
79 newinfo = (malloc_info *) align(mdp, newsize * sizeof(malloc_info));
80 if (newinfo == NULL) {
81 mmorecore(mdp, -size);
84 memset((void *) newinfo, 0, newsize * sizeof(malloc_info));
85 memcpy((void *) newinfo, (void *) mdp->heapinfo,
86 mdp->heapsize * sizeof(malloc_info));
87 oldinfo = mdp->heapinfo;
88 newinfo[BLOCK(oldinfo)].busy.type = 0;
89 newinfo[BLOCK(oldinfo)].busy.info.block.size
90 = BLOCKIFY(mdp->heapsize * sizeof(malloc_info));
91 newinfo[BLOCK(oldinfo)].busy.info.block.busy_size = size;
92 mdp->heapinfo = newinfo;
93 __mmalloc_free(mdp, (void *) oldinfo);
94 mdp->heapsize = newsize;
97 mdp->heaplimit = BLOCK((char *) result + size);
101 /* Allocate memory from the heap. */
103 void *mmalloc(xbt_mheap_t mdp, size_t size)
106 size_t block, blocks, lastblocks, start;
111 /* Work even if the user was stupid enough to ask a 0-byte block, ie return a valid block that can be realloced or freed
112 * glibc malloc does not use this trick but return a constant pointer, but my hack is quicker to implement ;)
117 // printf("(%s) Mallocing %d bytes on %p (default: %p)...",xbt_thread_self_name(),size,mdp,__mmalloc_default_mdp);fflush(stdout);
119 if (!(mdp->flags & MMALLOC_INITIALIZED)) {
120 if (!initialize(mdp)) {
125 if (size < sizeof(struct list)) {
126 size = sizeof(struct list);
129 /* Determine the allocation policy based on the request size. */
130 if (size <= BLOCKSIZE / 2) {
131 /* Small allocation to receive a fragment of a block.
132 Determine the logarithm to base two of the fragment size. */
135 while ((size /= 2) != 0) {
139 /* Look in the fragment lists for a
140 free fragment of the desired size. */
141 next = mdp->fraghead[log].next;
143 /* There are free fragments of this size.
144 Pop a fragment out of the fragment list and return it.
145 Update the block's nfree and first counters. */
146 result = (void *) next;
147 next->prev->next = next->next;
148 if (next->next != NULL) {
149 next->next->prev = next->prev;
151 block = BLOCK(result);
152 if (--mdp->heapinfo[block].busy.info.frag.nfree != 0) {
153 mdp->heapinfo[block].busy.info.frag.first =
154 RESIDUAL(next->next, BLOCKSIZE) >> log;
158 /* No free fragments of the desired size, so get a new block
159 and break it into fragments, returning the first. */
160 //printf("(%s) No free fragment...",xbt_thread_self_name());
161 result = mmalloc(mdp, BLOCKSIZE);
162 //printf("(%s) Fragment: %p...",xbt_thread_self_name(),result);
163 if (result == NULL) {
167 /* Link all fragments but the first into the free list. */
168 for (i = 1; i < (size_t) (BLOCKSIZE >> log); ++i) {
169 next = (struct list *) ((char *) result + (i << log));
170 next->next = mdp->fraghead[log].next;
171 next->prev = &mdp->fraghead[log];
172 next->prev->next = next;
173 if (next->next != NULL) {
174 next->next->prev = next;
178 /* Initialize the nfree and first counters for this block. */
179 block = BLOCK(result);
180 mdp->heapinfo[block].busy.type = log;
181 mdp->heapinfo[block].busy.info.frag.nfree = i - 1;
182 mdp->heapinfo[block].busy.info.frag.first = i - 1;
185 /* Large allocation to receive one or more blocks.
186 Search the free list in a circle starting at the last place visited.
187 If we loop completely around without finding a large enough
188 space we will have to get more memory from the system. */
189 blocks = BLOCKIFY(size);
190 start = block = MALLOC_SEARCH_START;
191 while (mdp->heapinfo[block].free.size < blocks) {
192 block = mdp->heapinfo[block].free.next;
193 if (block == start) {
194 /* Need to get more from the system. Check to see if
195 the new core will be contiguous with the final free
196 block; if so we don't need to get as much. */
197 block = mdp->heapinfo[0].free.prev;
198 lastblocks = mdp->heapinfo[block].free.size;
199 if (mdp->heaplimit != 0 &&
200 block + lastblocks == mdp->heaplimit &&
201 mmorecore(mdp, 0) == ADDRESS(block + lastblocks) &&
202 (morecore(mdp, (blocks - lastblocks) * BLOCKSIZE)) != NULL) {
203 /* Which block we are extending (the `final free
204 block' referred to above) might have changed, if
205 it got combined with a freed info table. */
206 block = mdp->heapinfo[0].free.prev;
208 mdp->heapinfo[block].free.size += (blocks - lastblocks);
211 result = morecore(mdp, blocks * BLOCKSIZE);
212 if (result == NULL) {
215 block = BLOCK(result);
216 mdp->heapinfo[block].busy.type = 0;
217 mdp->heapinfo[block].busy.info.block.size = blocks;
218 mdp->heapinfo[block].busy.info.block.busy_size = size;
223 /* At this point we have found a suitable free list entry.
224 Figure out how to remove what we need from the list. */
225 result = ADDRESS(block);
226 if (mdp->heapinfo[block].free.size > blocks) {
227 /* The block we found has a bit left over,
228 so relink the tail end back into the free list. */
229 mdp->heapinfo[block + blocks].free.size
230 = mdp->heapinfo[block].free.size - blocks;
231 mdp->heapinfo[block + blocks].free.next
232 = mdp->heapinfo[block].free.next;
233 mdp->heapinfo[block + blocks].free.prev
234 = mdp->heapinfo[block].free.prev;
235 mdp->heapinfo[mdp->heapinfo[block].free.prev].free.next
236 = mdp->heapinfo[mdp->heapinfo[block].free.next].free.prev
237 = mdp->heapindex = block + blocks;
239 /* The block exactly matches our requirements,
240 so just remove it from the list. */
241 mdp->heapinfo[mdp->heapinfo[block].free.next].free.prev
242 = mdp->heapinfo[block].free.prev;
243 mdp->heapinfo[mdp->heapinfo[block].free.prev].free.next
244 = mdp->heapindex = mdp->heapinfo[block].free.next;
247 mdp->heapinfo[block].busy.type = 0;
248 mdp->heapinfo[block].busy.info.block.size = blocks;
249 mdp->heapinfo[block].busy.info.block.busy_size = size;
251 //printf("(%s) Done mallocing. Result is %p\n",xbt_thread_self_name(),result);fflush(stdout);